PhysicsICSE Class 10 · Chapter 2

Uniform Circular Motion ICSE Class 10: Centripetal and Centrifugal Force

Updated 14 October 2026 · Fact-checked

In uniform circular motion a body moves round a circle at constant speed, but its direction keeps changing, so it is accelerated. A real centripetal force acts towards the centre; the centrifugal force is an apparent outward force felt in the rotating frame. The centripetal force does no work.

What Uniform Circular Motion is about

A stone whirled on a string, the Moon round the Earth and a car on a circular track all show circular motion. If the speed stays the same, the motion is uniform circular motion. It is a classic example of motion at constant speed that is still accelerated, because velocity includes direction.

The CISCE 2027 syllabus covers uniform circular motion as an example of constant speed though acceleration (force) is present, and the differences between centripetal and centrifugal force. Numerical work on centripetal force is not part of this topic, but you should be able to find the speed of a body going round a circle from the circumference and time.

The CISCE examiners' comments for 2024 and 2025 show the usual slips: naming the force 'rotational' or 'tension force' instead of centripetal, writing 'constant' or a formula instead of 'zero' for the work done by the centripetal force, and placing the centrifugal force towards the centre or along the tangent.

Weightage: CISCE publishes no chapter or unit weightage for ICSE Physics. Uniform Circular Motion is in the 1. Force, Work, Power and Energy (ii) part of the 2027 syllabus and can be asked in both Section A and Section B of the 80-mark paper.Source: CISCE ICSE Physics (Science Paper 1) syllabus, examination year 2027

Key concepts

Uniform circular motion: constant speed, changing velocity

In uniform circular motion:

the speed is constant: equal distances along the circle in equal times;
the velocity keeps changing, because its direction changes at every point;
at each point the velocity is along the tangent to the circle.

Speed $= \frac{circumference}{time for one revolution} = \frac{2 π r}{T}$ .

Worked example

A stone tied to a string moves in a horizontal circle of radius 0.5 m, completing one revolution in 2 s. Find its speed. Is its velocity constant?

Try it first, then show the solutionSolution

$v = \frac{2 π \times 0.5}{2} = \frac{π}{2} \approx 1.57$ m/s.
The speed is constant, but the direction changes continuously, so the velocity is not constant.

Answer: About 1.57 m/s; velocity not constant

Why uniform circular motion is accelerated

Acceleration is the rate of change of velocity. Since the direction of velocity changes continuously, the velocity changes, so the body is accelerated even though its speed is constant.

This acceleration is directed towards the centre of the circle (centripetal acceleration). By Newton's second law, an acceleration needs a net force: the centripetal force.

Worked example

A car goes round a circular track at a steady 40 km/h. Is it accelerating? Give a reason.

Try it first, then show the solutionSolution

Its speed is constant.
Its direction of motion changes all the time, so its velocity changes.
A change of velocity means acceleration.

Answer: Yes: its velocity changes direction, so it is accelerated.

Centripetal force: a real force towards the centre

The centripetal force is the force, directed along the radius towards the centre, needed to keep a body moving in a circle. It is a real force, provided by some agent:

stone on a string: tension in the string;
Moon round the Earth, satellites: gravitational pull;
car turning on a level road: friction between tyres and road;
electron round the nucleus: electrostatic attraction.

Without it, the body would move in a straight line.

Worked example

Name the force that provides the centripetal force for (a) a stone whirled on a string, (b) the Earth going round the Sun.

Try it first, then show the solutionSolution

(a) The tension in the string, pulling the stone towards the hand (centre).
(b) The gravitational attraction of the Sun.

Answer: (a) Tension (b) Gravitational force of the Sun

Work done by the centripetal force is zero

At every instant the centripetal force is along the radius and the displacement is along the tangent, so they are perpendicular: $W = F s cos 9 0^{\circ} = 0$ .

So the centripetal force does no work, the speed does not change, and the kinetic energy stays constant. The reason is the angle of $9 0^{\circ}$ , not that the displacement is zero.

Worked example

A 0.2 kg stone moves in a circle at a steady 3 m/s. Find its kinetic energy, and the work done on it by the string during half a revolution.

Try it first, then show the solutionSolution

$K = \frac{1}{2} \times 0.2 \times 3^{2} = 0.9$ J.
The tension is always perpendicular to the motion, so the work done is 0 and $K$ stays 0.9 J.

Answer: 0.9 J; work done 0

Centrifugal force: an apparent outward force

A person inside a rotating system (a passenger in a bus taking a turn, a person on a merry-go-round) feels pushed outwards, away from the centre. This centrifugal force is not a real force applied by any agent; it is a fictitious (apparent) force that appears only when we describe motion from the rotating frame. Its magnitude equals that of the centripetal force and its direction is opposite.

Observed from the ground, the passenger simply tends to keep moving in a straight line (inertia), while the bus turns.

Worked example

Why do passengers in a bus lean outwards when the bus takes a sharp turn?

Try it first, then show the solutionSolution

The bus turns, but the passengers' bodies tend to continue in a straight line (inertia of direction).
Relative to the bus, they seem to be pushed outwards: the apparent centrifugal force.

Answer: Inertia of direction; in the bus's frame this appears as an outward centrifugal force.

Motion along the tangent when the force stops

If the centripetal force suddenly stops (the string breaks), the body moves off in a straight line along the tangent at the point where it was, by Newton's first law (inertia of direction). It does not fly outwards along the radius.

Examples: sparks from a grinding wheel fly off tangentially; mud flies tangentially from a spinning bicycle wheel; a hammer thrower releases the hammer so that its tangent points the right way.

Worked example

A stone whirled in a horizontal circle is at the northernmost point of the circle, moving east, when the string snaps. In which direction does it move?

Try it first, then show the solutionSolution

At that point the velocity is along the tangent, i.e. east.
With no centripetal force it continues in a straight line: east.

Answer: East, along the tangent

Centripetal and centrifugal force compared

Direction: centripetal towards the centre; centrifugal away from the centre.
Nature: centripetal is a real force (tension, gravity, friction); centrifugal is fictitious, felt only in the rotating frame.
Origin: centripetal is produced by an agent; centrifugal arises from inertia, with no agent.
Need: centripetal force is needed for any circular motion; centrifugal force does not cause anything in the ground frame.
Both have the same magnitude for a given motion.

Worked example

Write two differences between centripetal and centrifugal force.

Try it first, then show the solutionSolution

Centripetal acts towards the centre; centrifugal acts away from the centre.
Centripetal is a real force with an agent; centrifugal is an apparent force felt only in a rotating frame.

Answer: Direction and nature (real vs apparent)

Physics in real life: Uniform Circular Motion

Each concept, met in an everyday situation. Read the situation, try the problem, then check the solution. The one-line hook is what to remember.

Speed on a circular track

Suppose a cyclist rides round a circular track of radius 70 m at constant speed and completes one round in 44 s.

Find the cyclist's speed and the displacement after one full round. (Use $π = \frac{22}{7}$ .)

Try it first, then show the solutionSolution

Circumference $= 2 \times \frac{22}{7} \times 70 = 440$ m.
Speed $= \frac{440}{44} = 10$ m/s.
After one round the cyclist is back at the start: displacement $= 0$ .

Answer: 10 m/s; displacement 0

Memory hook: Full circle: lots of distance, no displacement.

Friction as centripetal force

Imagine a car taking a turn on a level road that has a patch of spilt oil.

Why might the car skid outwards on the oily patch?

Try it first, then show the solutionSolution

On a level road, friction between the tyres and the road provides the centripetal force.
Oil reduces friction, so the force towards the centre is too small; the car tends to continue straight, along the tangent, and skids off the curve.

Answer: Too little friction to supply the centripetal force

Memory hook: No grip, no turn.

Spin dryer

Suppose the drum of a washing machine spins clothes rapidly in a circle and has small holes in its wall.

Why does water leave the clothes through the holes?

Try it first, then show the solutionSolution

The drum wall pushes the clothes towards the centre, giving them the centripetal force.
At the holes nothing pushes the water inwards, so the water continues along the tangent and leaves the drum.

Answer: Water at the holes gets no centripetal force and moves off tangentially.

Memory hook: Where the push stops, the water flies straight.

Topics in this chapter

Uniform Circular Motion formula sheet

Speed in uniform circular motion: $v = \frac{2 π r}{T}$; T = time for one revolution.
Work by the centripetal force: $W = F s cos 9 0^{\circ} = 0$; Force along the radius, motion along the tangent.
Kinetic energy (constant here): $K = \frac{1}{2} m v^{2}$; Speed is constant, so K is constant.
Displacement after one revolution: $displacement = 0, distance = 2 π r$; Half a revolution: displacement = 2r.

Uniform Circular Motion: diagrams to practise

Practise each one on paper: draw it from the checklist, then tick off every label.

Stone whirled in a horizontal circle

To show velocity, centripetal force and the path when the string breaks.

Draw

A circle with its centre O (the hand).
The stone at a point P on the circle, joined to O by the string.
An arrow along the tangent at P for velocity.
An arrow from P towards O for the centripetal force (tension).
A dashed straight line along the tangent from P for the path if the string breaks.

Label

Centre O
Radius (string)
Velocity v along the tangent
Centripetal force towards O
Path after the string breaks (tangent)

Watch out: Velocity and centripetal force are at right angles: that is why the work done is zero.

How the board asks Uniform Circular Motion

The question patterns to expect, and the method that works for each.

Question type	How it is asked	Method
MCQ: what changes and what stays constant	Section A, Question 1: speed, velocity, acceleration, kinetic energy in uniform circular motion.	Speed and KE constant; velocity and acceleration change direction.
Fill in the blanks	Question 2: the force that keeps a stone in a circle; the work done; direction of centrifugal force.	Centripetal; zero; away from the centre.
Short reasons	Why is uniform circular motion accelerated? Why does a stone fly off along a tangent?	Velocity direction changes; inertia of direction.
Differences	Two or three differences between centripetal and centrifugal force.	Direction, real vs apparent, agent vs no agent.
Simple numerical	Speed from radius and period; distance and displacement after part of a revolution.	v = 2πr ÷ T; displacement is a straight line between start and end.

Tricks to remember Uniform Circular Motion

Short memory aids. Say each one aloud once, then use it on a question the same day.

Petal in, fugal out
Centri-PETAL: 'seek' the centre (inwards). Centri-FUGAL: 'flee' the centre (outwards).
Use it when: Directions of the two forces.
Same speed, new direction
Uniform circle = same speed, ever-changing direction = acceleration.
Use it when: Explaining why it is accelerated.
Right angle, no work
Force inwards, motion sideways: 90° means zero work.
Use it when: Work done by the centripetal force.
Snap, then tangent
When the string snaps, the stone goes straight along the tangent, not out along the radius.
Use it when: Release questions.

Uniform Circular Motion: board-level solved questions

Ordered from board level to HOTS. Cover the solution, write your own, then compare step by step.

Example 1: What stays constant · 1 mark · MCQBoard level

For a body in uniform circular motion, the quantity that remains constant is its:
(a) velocity
(b) speed
(c) acceleration
(d) direction of motion

Try it first, then show the solutionSolution

Only the magnitude of velocity (speed) is unchanged.

Answer: (b)

Example 2: Accelerated though speed is constant · 1 mark · Assertion-reasonBoard level

Assertion (A): Uniform circular motion is accelerated motion.
Reason (R): In uniform circular motion, the direction of the velocity changes continuously.
(a) (A) is true and (R) is false.
(b) (A) is false and (R) is true.
(c) Both (A) and (R) are true, and (R) is the correct explanation for (A).
(d) Both (A) and (R) are true, but (R) is not the correct explanation for (A).

Try it first, then show the solutionSolution

A changing velocity means acceleration.

Answer: (c)

Example 3: A satellite's circular orbit · 2 marks · Very short answerBoard level

A satellite moves in a circular orbit round the Earth at constant speed. (a) Which force provides the centripetal force? (b) In which direction is its velocity at any point?

Try it first, then show the solutionSolution

(a) The gravitational pull of the Earth.
(b) Along the tangent to the orbit at that point.

Answer: (a) Earth's gravity (b) along the tangent

Example 4: Speed and displacement on a track · 3 marks · Short answerHarder board level

A cyclist goes round a circular track of radius 70 m at constant speed, taking 44 s per round. Find (a) the speed, (b) the displacement and average velocity for half a round. (Use $π = \frac{22}{7}$ .)

Try it first, then show the solutionSolution

(a) $v = \frac{2 \times \frac{22}{7} \times 70}{44} = 10$ m/s.
(b) After half a round the cyclist is at the opposite end of a diameter: displacement $= 140$ m.
Average velocity $= \frac{140}{22} \approx 6.36$ m/s, along that diameter (less than the speed of 10 m/s).

Answer: (a) 10 m/s (b) 140 m; about 6.36 m/s

Example 5: When the string breaks · 3 marks · Short answerHarder board level

A stone is whirled in a horizontal circle and the string suddenly breaks. (a) In which direction does the stone move? (b) Which law explains this? (c) Why does it not move outward along the radius?

Try it first, then show the solutionSolution

(a) Along the tangent at the point where the string broke.
(b) Newton's first law: the stone keeps its velocity (inertia of direction).
(c) No outward force acts on the stone in the ground frame; once the inward tension disappears, nothing changes its velocity, which was along the tangent.

Answer: Along the tangent; Newton's first law

Example 6: Two differences · 2 marks · Long answerBoard level

State two differences between centripetal force and centrifugal force.

Try it first, then show the solutionSolution

Centripetal force acts towards the centre; centrifugal force acts away from the centre.
Centripetal force is real (provided by tension, gravity, friction, etc.); centrifugal force is apparent, felt only in a rotating frame.

Answer: Direction; real vs apparent

Example 7: A car on a curve · 3 marks · Long answerHarder board level

A car takes a circular turn on a level road at constant speed. (a) Which force provides the centripetal force? (b) What happens if the road is very slippery? (c) Why do the passengers feel pushed outwards?

Try it first, then show the solutionSolution

(a) Friction between the tyres and the road, directed towards the centre of the turn.
(b) Friction is too small, so the car cannot follow the curve; it tends to move along the tangent and skids outwards.
(c) Their bodies tend to keep moving straight (inertia); relative to the turning car this feels like an outward (centrifugal) force.

Answer: Friction; the car skids; inertia felt as centrifugal force

Example 8: Zero work and constant kinetic energy · 4 marks · Long answerHOTS / competency

A stone of mass 0.2 kg moves in a horizontal circle at a constant speed of 3 m/s. (a) Find its kinetic energy. (b) Show that the centripetal force does no work. (c) What is the work done in one full revolution? (d) A student says the work is zero because the displacement in one revolution is zero. Is this the correct reason? Explain.

Try it first, then show the solutionSolution

(a) $K = \frac{1}{2} \times 0.2 \times 9 = 0.9$ J.
(b) At every instant the force is along the radius and the motion along the tangent: $θ = 9 0^{\circ}$ , $cos 9 0^{\circ} = 0$ , so $W = 0$ .
(c) Zero.
(d) No. The work is zero at every instant, even over a quarter turn where the displacement is not zero; the reason is that force and motion are perpendicular, which is why the speed and $K$ never change.

Answer: (a) 0.9 J (c) 0 (d) No: the 90° angle is the reason

Case-study practice (Section B style)

Read the situation, then answer every part. In the board paper this is a 10-mark question split into 3 + 3 + 4 marks.

A spin dryer

The drum of a spin dryer has radius 0.25 m and small holes in its wall. In the spin cycle it makes 20 revolutions per second.

(i) · 3 marks
What provides the centripetal force on the clothes, and in which direction does it act?
Answer
Answer: The drum wall; towards the axis
The wall of the drum pushes on the clothes (normal reaction), towards the axis (centre) of the drum. This keeps them moving in a circle.
(ii) · 3 marks
Explain why water leaves the clothes through the holes.
Answer
Answer: No centripetal force at the holes; tangent motion
Water at a hole has nothing pushing it inwards, so it is not made to follow the circle; it continues in a straight line along the tangent and passes out through the hole.
(iii) · 4 marks
Find the speed of a point on the drum wall (to 1 decimal place), and say whether its velocity is constant.
Answer
Answer: About 31.4 m/s; not constant
Time for one revolution $T = \frac{1}{20}$ s. $v = \frac{2 π \times 0.25}{0.05} = 10 π \approx 31.4$ m/s. The speed is constant but the direction changes, so the velocity is not constant.

The hammer throw

Imagine an athlete whirls a hammer on a wire in a circle of radius 1.2 m, making one revolution in 0.5 s, before letting go.

(i) · 3 marks
Which force keeps the hammer moving in a circle, and what provides it?
Answer
Answer: Centripetal force; tension in the wire
The centripetal force, directed towards the athlete (centre), is provided by the tension in the wire pulled by the athlete.
(ii) · 3 marks
Find the speed of the hammer just before release (to 2 decimal places).
Answer
Answer: About 15.08 m/s
$v = \frac{2 π \times 1.2}{0.5} = 4.8 π \approx 15.08$ m/s.
(iii) · 4 marks
In which direction does the hammer travel just after release, and why must the athlete time the release carefully?
Answer
Answer: Along the tangent at the release point
With the tension gone, no force acts towards the centre, so the hammer moves along the tangent at the point of release (inertia of direction). The tangent direction changes round the circle, so releasing at the right moment points the hammer into the landing area.

Where the marks are

How a typical answer is split into step marks. Show every step: a right final answer alone rarely earns full marks.

A ball on a string moves in a circle of radius 0.7 m, making one revolution every 2.2 s. Find its speed. (Use $π = \frac{22}{7}$ .) (2 marks)

Step	Marks
$v = \frac{2 π r}{T} = \frac{2 \times \frac{22}{7} \times 0.7}{2.2}$	1
$= 2$ m/s	1

State three differences between centripetal and centrifugal force. (3 marks)

Step	Marks
Direction: towards the centre vs away from the centre	1
Nature: real force vs apparent (fictitious) force	1
Origin: produced by an agent (tension, gravity, friction) vs arises in a rotating frame due to inertia	1

Explain why uniform circular motion is accelerated, name the force responsible, and state the work done by this force. (4 marks)

Step	Marks
Speed constant but direction of velocity changes continuously	1
Change in velocity means acceleration, directed towards the centre	1
Force: centripetal force (e.g. tension, gravity)	1
Work done = 0, since force ⟂ displacement	1

Where students lose marks in Uniform Circular Motion

The slips examiners see most often, and what to write instead.

Mistake: Wrong name for the force
CISCE examiners' comments, 2024: for a stone whirled on a string, candidates wrote 'rotational force' or 'tension force' instead of 'centripetal force' for the force needed for circular motion.
Do this: The tension is what provides it; the force needed for circular motion is called the centripetal force.
Usually costs: 1 mark.
Mistake: Work done not zero, or zero for the wrong reason
CISCE examiners' comments, 2024: candidates wrote 'constant', gave the formula W = F × s, or left it blank; some wrote zero thinking the displacement is zero on a circular track.
Do this: Zero, because the force is perpendicular to the displacement at every instant.
Usually costs: 1 mark.
Mistake: Centrifugal force in the wrong direction
CISCE examiners' comments, 2025: candidates said the centrifugal force acts towards the centre (confusing it with centripetal) or along the tangent (confusing it with velocity).
Do this: Centrifugal: away from the centre. Velocity: along the tangent. Centripetal: towards the centre.
Usually costs: 1 mark.
Mistake: Calling the velocity constant
Uniform circular motion has constant speed but not constant velocity; answering 'velocity is constant' contradicts the syllabus statement that acceleration is present.
Do this: Always separate speed (magnitude) from velocity (magnitude and direction).
Usually costs: 1 mark in MCQs and reasons.

Practice questions on Uniform Circular Motion

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

Q1 · 1 mark · MCQBoard level
In uniform circular motion, the centripetal force acts:
(a) along the tangent
(b) towards the centre
(c) away from the centre
(d) perpendicular to the plane of the circle
Hint
Centre-seeking.
Answer
(b)
Q2 · 1 mark · MCQBoard level
The centrifugal force on a body in uniform circular motion is:
(a) a real force towards the centre
(b) an apparent force away from the centre
(c) a real force along the tangent
(d) zero
Hint
Felt in the rotating frame.
Answer
(b)
Q3 · 1 mark · MCQHarder board level
A stone is whirled in a vertical circle and the string breaks at the lowest point. Just after this, the stone moves:
(a) vertically downwards
(b) towards the centre
(c) horizontally, along the tangent
(d) outwards along the radius
Hint
Velocity at the lowest point is horizontal.
Answer
(c) (gravity then makes it curve downwards)
Q4 · 1 mark · Assertion-reasonBoard level
Assertion (A): The work done by the centripetal force on a body in uniform circular motion is zero.
Reason (R): The centripetal force is perpendicular to the displacement at every instant.
(a) (A) is true and (R) is false.
(b) (A) is false and (R) is true.
(c) Both (A) and (R) are true, and (R) is the correct explanation for (A).
(d) Both (A) and (R) are true, but (R) is not the correct explanation for (A).
Hint
W = Fs cos θ.
Answer
(c)
Q5 · 2 marks · Very short answerHarder board level
Name the force that provides the centripetal force for (a) the Moon going round the Earth, (b) an electron going round the nucleus.
Hint
Gravity and electrostatics.
Answer
(a) Gravitational attraction of the Earth (b) Electrostatic attraction of the nucleus
Q6 · 2 marks · Short answerHarder board level
For a body in uniform circular motion, state whether each changes or stays constant: (a) speed, (b) velocity, (c) kinetic energy, (d) direction of acceleration.
Hint
Direction keeps changing.
Answer
(a) constant (b) changes (c) constant (d) changes (always towards the centre)
Q7 · 3 marks · Long answerBoard level
(a) Define uniform circular motion. (b) Why is it called accelerated motion? (c) Give one example.
Hint
Speed vs velocity.
Answer
(a) Motion of a body along a circular path at constant speed. (b) Its velocity changes direction at every point, so it has an acceleration. (c) The tip of a clock's second hand, or a satellite in a circular orbit.
Q8 · 3 marks · Long answerHarder board level
A runner goes round a circular track of radius 35 m at constant speed, completing a round in 55 s. Find (a) the speed, (b) the distance and displacement after one and a half rounds. (Use $π = \frac{22}{7}$ .)
Hint
Circumference 220 m.
Answer
(a) $\frac{220}{55} = 4$ m/s. (b) Distance $= 330$ m; displacement $= 70$ m (a diameter).
Q9 · 4 marks · Long answerHOTS / competency
A coin is placed on a rotating turntable. As the turntable is made to spin faster, the coin slides off. (a) Which force provided the centripetal force on the coin? (b) Why does it slide off at high speed? (c) In which direction does it leave, as seen from the ground? (d) Why is 'the centrifugal force threw it off' not a correct explanation from the ground frame?
Hint
Friction has a maximum value.
Answer
(a) Friction between the coin and the turntable. (b) At higher speed a larger centripetal force is needed; friction cannot supply it. (c) Along the tangent at the point where it slips. (d) From the ground no outward force acts; the coin simply keeps moving straight because the inward friction is not enough.
Q10 · 3 marks · Long answerHarder board level
Give the reason in each case: (a) sparks from a grinding wheel fly off along tangents, (b) mud flies off a spinning bicycle wheel, (c) a cyclist leans inwards on a curve.
Hint
Tangent motion; providing an inward force.
Answer
(a) Hot particles lose contact, so no centripetal force acts; they keep their tangential velocity. (b) Adhesion of the mud cannot provide the needed centripetal force. (c) Leaning inwards lets the forces on the cyclist provide the inward (centripetal) force needed to go round the curve.
Q11 · 1 mark · MCQHOTS / competency
A body moves in a circle at constant speed. Which statement is correct?
(a) Its kinetic energy and momentum are both constant.
(b) Its kinetic energy is constant but its momentum changes in direction.
(c) Its kinetic energy changes but its momentum is constant.
(d) Both change.
Hint
KE depends on speed; momentum is a vector.
Answer
(b)
Q12 · 4 marks · Long answerHOTS / competency
A satellite moves in a circular orbit of radius 7000 km at a constant speed of 7.5 km/s. (a) Find the time for one orbit in minutes (to 1 decimal place). (b) Gravity acts on the satellite all the time; why does its speed not increase? (c) What would happen to its path if gravity were suddenly switched off?
Hint
T = 2πr ÷ v.
Answer
(a) $T = \frac{2 π \times 7000}{7.5} \approx 5864$ s $\approx 97.7$ minutes. (b) Gravity acts towards the centre, perpendicular to the velocity, so it does no work and the speed stays the same; it only turns the velocity. (c) The satellite would move off in a straight line along the tangent.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1.What is uniform circular motion?Show answer
Motion in a circle at constant speed.
2.Why is it accelerated?Show answer
The direction of velocity changes continuously.
3.Direction of centripetal force?Show answer
Towards the centre.
4.Direction of centrifugal force?Show answer
Away from the centre.
5.Is centrifugal force real?Show answer
No, it is an apparent force felt in a rotating frame.
6.Work done by the centripetal force?Show answer
Zero.
7.Path when the string breaks?Show answer
Along the tangent.

Best order to study it

Speed vs velocity in circular motion.
Why the motion is accelerated.
Centripetal force and its sources.
Zero work by the centripetal force.
Centrifugal force and the differences.
Tangent motion and everyday examples.

Quick revision checklist

The night before the exam: can you do each of these without looking?

Can you say what is constant and what changes?
Can you name the centripetal force in five situations?
Do you know why the work done is zero?
Can you give three differences between centripetal and centrifugal force?
Can you find speed from radius and time period?

Uniform Circular Motion: frequently asked questions

Are centripetal force formulas in the ICSE Class 10 syllabus?

The syllabus treats uniform circular motion qualitatively: constant speed with acceleration, and the differences between centripetal and centrifugal force. Formula-based numericals on centripetal force are not part of it.

Is centrifugal force the reaction to centripetal force?

No. Centrifugal force is an apparent force used only when describing motion from a rotating frame; it does not act on another body as a reaction would.

Does the speed change in uniform circular motion?

No. The speed is constant; only the direction of motion changes.

Why does mud fly off a spinning wheel?

The mud's adhesion cannot provide enough centripetal force, so it moves off along the tangent.

What happens to kinetic energy in uniform circular motion?

It stays constant, because the speed is constant and the centripetal force does no work.

Based on: CISCE ICSE 2027 Physics (Science Paper 1) syllabus; CISCE ICSE 2027 Physics (Science Paper 1) specimen question paper and marking scheme; CISCE Analysis of Pupil Performance, ICSE Physics (Science Paper 1), 2025; CISCE Analysis of Pupil Performance, ICSE Physics (Science Paper 1), 2024