# Circular motion 3d for IGCSE Physics

Topic:
Circle

The physics curriculum for GCSE & IGCSE does not require students to perform analysis of motion in a circle quantitively. However, students are required understand the effect of changing the mass, speed and radius on the centripetal force required to keep a body moving in a circle.. This simulation is inspired by an excellent experiment suggested by Hodder Education's GCSE physics textbook . ﻿Using the simulation :
1. Start the simulation, and adjust the parameters (m: Mass, v: speed, F: centripetal force to values in the middle of their respective ranges. Your aim should get a value of the Radius between 0.75 and 1.00 m
2. Note down the value of the radius.
3. Now change EITHER the mass OR the speed of the moving body.
4. Finally try to restore the radius noted in (2) above by adjusting the value of the required centripetal force F. (try to get a value of the Radius as close as possible to the initial value) This exercise will show what change in F is needed to maintain circular motion.
5. Repeat steps 1 to 4 until you fully understand the relationship between the various parameters, then answer the questions below.

## Q1 [1 Mark]

Complete the sentences by selecting the correct ending : (i) When a mass moves in a circle at a steady speed the centripetal force is larger if the :

Check all that apply

## Q2 [1 Mark]

When a mass moves in a circle at a steady speed the centripetal force is larger if the :

Check all that apply

## Q3 [1 Mark]

An apple is whirled round in a horizontal circle on the end of a string which is tied to the stalk. It is whirled faster and faster and at a certain speed the apple is torn from the stalk. Suggest reasons why ? [1 Mark]

## Q4 [1 Mark]

A car rounding a bend travels in an arc of a circle. a) What provides the centripetal force?

## Q5 [3 Mark]

b) Is a larger or a smaller centripetal force required if

1. the car travels faster
2. the bend is less curved,
3. the car has more passengers?

## Q6 : A girl swings a small mass on a rope around her head.

a. Which force provides the centripetal force? [1 Mark]

b. In which direction does this force act? [1 Mark]

﻿c. What is the direction of the acceleration of the object [1 Mark]

d. Describe the motion of the object if the rope is cut [2 Mark]

## Q6

Which description of the forces acting on the car is correct? [1 Mark]

Check all that apply

## (a) A force acts on the car to keep it moving in a circle.

1. Draw an arrow on Fig. 7.1 to show the direction of this force. (Use the arrow tool ) [2 Marks]

(ii) The speed of the car increases. State what happens to the magnitude of this force. [1 Mark]

## (b) The car travels too quickly and leaves the track at P.

(i) - On Fig. 7.1, draw an arrow to show the direction of travel after it has left the track. [1 Mark]

(ii) In terms of the forces acting on the car, suggest why it left the track at P. [2 Mark]