Forces

A tractor pulls a trailer at a constant speed. The tractor exerts a forward force of 1600 N on the trailer. What is the force exerted by the trailer on the tractor?

• 0 N

• 1600 N backwards

• 1600 N forwards

• 3200 N forwards

A force is applied to a body. Which property of the body cannot be changed by the force?

• its mass

• its shape

• its size

• its velocity

An object falls from rest through the air and the air resistance on it increases. The object reaches terminal velocity. Which quantity decreases until its terminal velocity is reached?

• acceleration

• kinetic energy

• speed

• weight

Each diagram shows two forces that are equal in magnitude. Which diagram shows two forces that are a Newton’s third law pair of forces?

• A

• B

• C

• D

Two forces of 3.0 N and 4.0 N act at right-angles to each other. Which diagram shows the resultant R of these forces?

• A

• B

• C

• D

The minimum distance in which a car can stop once the brakes are applied, is known as

• thinking distance

• stopping distance

• braking distance

• reaction time

The minimum braking distance for a car is tested on a dry road. The test is then repeated on a wet road. What happens to the braking distance and to the frictional force between the tyres and the road?

• A

• B

• C

• D

A force of 20 N pushes an object of mass 5.0 kg along a rough horizontal surface where the frictional force is 5.0N. What is the acceleration of the object?

• 1.0 m/s²

• 2.0 m/s²

• 3.0 m/s²

• 4.0 m/s²

How is the motion of a body affected by balanced and unbalanced forces acting on it?

• A

• B

• C

• D

A wooden block is pushed across a table at constant speed.

Which statement is correct?

• The frictional force increases as the block moves at constant speed.

• The frictional force is equal and opposite to the pushing force.

• The frictional force is greater than the pushing force.

• The frictional force is less than the pushing force.