Effects of Forces (CIE IGCSE Physics)

The mass of a small steel ball is 120 g. The volume of the ball is 16.0 cm³.

Fig. 3.1 shows the vertical forces that act on a large plastic ball as it is falling.

A load is attached to a spring, as shown in Fig. 3.1. Two arrows indicate the vertical forces acting on the load. The spring and the load are stationary.

[1]

The load is pulled downwards and then released. The load moves up and down.

Fig. 3.2 represents the vertical forces acting on the load at some time after it is released.

Calculate the resultant force on the load and state its direction.

resultant force = ........................................................... N
direction = ............................................................... 

Fig. 1.1 shows an aeroplane accelerating uniformly on a runway. 

Fig. 1.1

The aeroplane has a mass of 3.1 × 10⁶ kg. 

From rest, the aeroplane reaches a speed of 70 m/s after 32 s.

Calculate the following quantities

When the aeroplane reaches its destination, air traffic control directs it to circle the airfield until there is a safe time to land.

Fig. 1.2 shows a head on view of the aeroplane flying at a constant speed in a circular horizontal path. 

Fig 1.2

Draw an arrow showing the resultant force on the aeroplane.

Explain your answer.

The pilot wants to decrease the radius of the circular flight path whilst maintaining a constant speed.

Suggest how the pilot could achieve this.

As the aeroplane lands on the runway, it decelerates from its top speed. The resultant force on the aeroplane is less than it was at take off. 

Explain why this is the case.

A resultant force acts on an object at rest. 

State the direction of the acceleration.

Extended

A resultant force acts perpendicularly on a object traveling at a constant speed. 

State the effect of the force on the object.

A man with a mass of 70 kg steps into an elevator. 

Fig. 3.1 shows the vertical forces on a rocket.

Calculate the resultant force on the rocket.

resultant force = ........................................................... N

direction = ...........................................................

Fig. 3.2 shows the speed and direction of motion of an object at a point in time.

The resultant force on the object is zero for 10 seconds.

Deduce the speed and direction of motion after 5 seconds. Indicate the speed and direction of the object by drawing a labelled arrow next to the object in Fig. 3.3.

Fig. 3.1 shows a spring with no load attached. Fig. 3.2 shows the same spring with a load attached.

Describe how a student can determine the extension of the spring. You may draw on Fig. 3.1 and Fig. 3.2 as part of your answer.

The student plots a graph of load against extension, as shown in Fig. 3.3.

Calculate the mass that has a weight of 6.0 N.

Fig. 3.1 shows the horizontal forces acting on a swimmer.

size of resultant horizontal force = ...................................................... N

direction of resultant horizontal force = ......................................................    

[1]

[1]

[2]

Another swimmer weighs 700N. He stands on a diving board, as shown in Fig. 3.3.

Calculate the moment of the swimmer’s weight about point P.

Extended Only

A car travels around a circular track at constant speed.

Explain why it is incorrect to describe the circular motion as having constant velocity.

Extended Only

A force is required for the car to maintain the circular motion.

Explain why a force is required.

Extended Only

State the direction in which the force acts for objects in circular motion.

Extended Only

State the name of this force for the car on the track.