Forces (Edexcel GCSE Physics)

A student investigates the relationship between force and acceleration for a trolley on a runway. Figure 12 shows some of the apparatus the student uses.

Figure 12

i) Describe how the student could increase the accelerating force applied to the trolley.

[2]

ii) Describe how the mass of the moving system can be kept constant.

[2]

iii) Explain how the student could improve the procedure to compensate for the effects of frictional forces acting on the trolley.

[2]

Higher Tier Only

 Figure 13 shows two objects, Q and R, before and after they collide.

Figure 13

The arrows show the direction of movement of the objects.

The arrows are not to scale.

Explain how momentum is conserved in the collision.

Use Newton’s third law and Newton’s second law in your answer. Newton’s second law can be written as

The force that keeps an object moving in a circular path is known as the

Figure 11 shows an object moving in a circular path.

Figure 11

i) Draw an arrow on Figure 11 to show the direction of the force that keeps the object moving in a circular path.

[1]

ii) The object in Figure 11 is moving at constant speed.

Explain why it is not moving with constant velocity.

[2]

Figure 12 shows a skier on a slope.

The skier travels down the slope with a constant acceleration.

The speed of the skier is measured at points P and Q.p

Figure 12

The table in Figure 13 gives some data about the skier making one downhill run.

Figure 13

i) Calculate the distance from P to Q.

Use an equation selected from the list of equations at the end of this paper.

distance from P to Q = .................................. m[3]

ii) Calculate the time taken for the skier to travel from P to Q.

time from P to Q = .............................. s[3]

A student carries out an experiment to determine the relationship between the force applied to an object and the object's acceleration.

She sets up her apparatus as shown in Figure 1.

Figure 1

She places a number of masses on top of the trolley and then removes them, one at a time, placing them on the mass hanger in order to increase the force.

Explain why she keeps the unused masses on top of the trolley.

Figure 2 shows some of the results of the experiment.  

  Figure 2

Figure 3 shows the graph of the results.

Figure 3

Another student says that there is an anomalous data point.

Circle this point and suggest how the first student could confirm that this is an anomalous data point. 

Use the graph to calculate the mass of the trolley and weight system. Clearly show your method.

The experiment is repeated on a rougher carpeted surface.

There is a stronger, constant frictional force of 0.2 N acting on the trolley when it moves. 

Sketch a new line on Figure 1 of the results of this second experiment. 

A student draws a Newton's third law pair of forces on a book, as shown in Figure 1.

Figure 1

F_g is the gravitational force and F_N is the normal reaction force.

State and explain whether the student has drawn a Newton's third law pair of forces correctly.

A child balances on a pogo stick as shown in Figure 2. The child and the pogo stick are both stationary.

Figure 2

Using Newton's second and third laws, explain how the child moves upwards when they exert a downward force on the spring.

Explain, using Newton's Third Law, how the forces on a person's foot enables them to walk on the ground.

A teacher is running late for a class. He sets off and exerts a force of 8.5 N on the ground. 

The mass of the Earth is 6.0 × 10²⁴ kg.

Calculate the theoretical acceleration of the Earth resulting from this step. Give your answer to 2 significant figures.

Higher Tier Only

The Sun lies at the centre of our solar system, with all other bodies, such as planets, orbiting it.

Figure 1 shows shows a model of the orbits of some of the planets in the solar system. 

Figure 1

Assume these orbits are circular.

Draw the resultant forces acting on Mercury, Venus, Earth and Mars.

Higher Tier Only

Describe the centripetal force acting in Figure 1.

Higher Tier Only

Mercury has an orbital period of 88 days. 

Compare the speed and velocity of Mercury in Figure 1 to Mercury 44 days after its position in Figure 1.

On Mercury's surface, the gravitational field strength is 3.7 N/kg.

A space probe has a weight of 5000 N on Earth. 

Calculate the probe's weight on Mercury.

Figure 1 shows a man attempting to push a large rock, and identifies some of the forces acting in this system.

Figure 1

 Which forces in the list correctly identify the force pairs in this scenario? Tick (✓) two boxes.   

Unable to push the rock, the man wonders whether he would be able to push it if it was on the Moon.

The Moon has a gravitational field strength of 1.6 N/kg. 

The frictional force the man is doing work against is directly proportional to the rock's weight.

Calculate how many times easier it would be to push the rock on the Moon compared to Earth, assuming the rock is pushed on the same type of surface.

The rock has a mass of 850 kg. 

Calculate the size of the normal reaction of the Moon's surface on the rock.

Higher Tier Only

A student throws a tennis ball vertically upwards and catches it as it returns to her.

Figure 1 shows the motion of the ball whilst it is in the air. 

Figure 1

 Draw a free-body force diagram of the ball at position C.

Higher Tier Only

Explain the motion of the ball in terms of the forces acting upon it at each position throughout its journey.

One force that acts on the ball is weight. This force is part of a force pair obeying Newton's third law. 

Describe the other force in the pair.

Higher Tier Only

Figure 1 shows a skier being towed with a rope at a constant speed whilst sinking into the snow. 

Figure 1

State the name of each of the forces A - D acting on the skier.

Higher Tier Only

Which of the following statements are true about the forces acting on the skier?  

Tick (✓) two boxes.

A second skier uses the same system as the skier in part (a).

While being towed by a force of 200 N in the rope, the skier is also pushing themselves forward with a force of 150 N.

The second skier has a weight of 600 N and is accelerating forwards at 1.5 m/s².

Calculate the magnitude of the resistive forces on the skier.