P6 Forces

A girl is jumping up and down on a trampoline. What are forces X and Y?

• X: Frictional force

  Y: Gravitational force

• X: Magnetic force

  Y: Elastic spring force

• X: Gravitational force

  Y: Elastic spring force

• X: Elastic spring force

  Y: Gravitational force

The activities show forces in action. Which of the following correctly describes the forces in action?

• (1)

• (2)

• (3)

• (4)

Four identical magnets were suspended from the ceiling using identical springs, as shown in the diagram. Objects A, B and C were placed under three of the magnets. Which one is correct?

• C is a magnet.

• A and C are magnets

• A is a block of wood.

• B and C are blocks of wood.

Arthur kicks a ball from point A to point B as shown in the diagram.

• (1) The mass of the ball changes from point A to point B.

• (2) The potential energy of the ball decreases from point A to point B.

• (3) There is no friction between the moving ball and the surrounding air.

• (4) The gravitational force acting on the ball remains the same from point A to point B.

Stephen pulled a weight hanger with a weight placed on it towards as shown in the diagram. Which one shows the relationship between the mass of the weights and the force needed to pull the weight hanger?

• 
• 
• 
• 

On a rainy day, Mr Lim, was travelling at 50 km/h. He saw a rock in front of him on the road and stepped on the brakes immediately. His car travelled a distance of 20m (braking distance) before it came to a complete stop. Would the braking distance be longer or shorter?

• Shorter. There is more frictional force between the tyres and the floor.

• Longer. There is lesser frictional force between the tyres and the floor.

• Longer. There is more frictional force between the tyres and the floor.

• Shorter. There is lesser frictional force between the tyres and the floor.

Samuel conducted a paper race with two pieces of paper by dropping them from a given height. One piece of paper was a flat sheet of paper and the other was crumpled, as shown. What are the forces acting on the paper as it falls to the ground?

• Gravitational force

• Elastic spring force

• Magnetic force

• Frictional force

Samuel conducted a paper race with two pieces of paper by dropping them from a given height. One piece of paper was a flat sheet of paper and the other was crumpled, as shown. Why did the crumpled ball of paper reach the ground first in all three tries?

• The paper has lesser area of contact. There is lesser frictional force between crumpled ball of paper and the air.

• The paper has more area of contact. There is more frictional force between crumpled ball of paper and the air.

• The paper has lesser area of contact. There is more gravitational force pulling the crumpled ball of paper to the ground.