4 Forces 2023

Forces are applied to four identical objects.

The length of each arrow indicates the magnitude of the force. Which object is in equilibrium?

The diagrams show four identical objects.

Each object is acted on by only the forces shown.

Which diagram shows an object in equilibrium?

A satellite orbits the Earth at constant speed in a circular orbit. Which statement is correct?

• The resultant force on the satellite is zero.

• The resultant force on the satellite is towards the Earth.

• The resultant force on the satellite is away from the Earth.

• The resultant force on the satellite is in the direction of its motion.

An object moves in a circle at constant speed.

Which statement about the force needed on the object is correct?

• A force away from the centre of the circle keeps the object moving in the circle.

• A force in the direction of motion of the object keeps it moving in the circle.

• A force towards the centre of the circle keeps the object moving in the circle.

• No force is needed to keep the object moving at constant speed in the circle.

A mass bounces up and down on a steel spring.

The diagram shows the mass and the spring at different points during the motion.

At which point is the least energy in the gravitational potential store of the mass and at which point is the most energy in the elastic store of the spring?

• mass moving down; mass moving up

• mass moving down; lowest point

• lowest point; mass moving up

• lowest point; lowest point

A cyclist is travelling in a straight line along a horizontal road at a constant speed.

A constant driving force F acts on the cyclist in the forward direction shown.

Which statement about the magnitude of the frictional forces acting on the cyclist is correct?

• The magnitude is equal to F.

• The magnitude is smaller than F, but greater than zero.

• The magnitude is greater than F.

• The magnitude is zero.

Which vector diagram correctly shows the force Z as the resultant of forces X and Y?

An object falls towards the surface of the Earth.

The object is falling at its terminal velocity.

Which statement is correct?

• There is air resistance and the acceleration of the object is negative.

• There is air resistance and the acceleration of the object is zero.

• There is no air resistance and the acceleration of the object is negative.

• There is no air resistance and the acceleration of the object is zero.

On the Earth, a spring stretches by 5.0 cm when a mass of 3.0 kg is suspended from one end.

The gravitational field strength on the Moon is 1/6 of that on the Earth.

Which mass, on the Moon, would stretch the spring by the same extension?

• 0.50 kg

• 3.0 kg

• 5.0 kg

• 18 kg

A train is travelling horizontally in a straight line.

A book is on a table in the train.

The diagram shows all the forces acting on the book.

How is the train moving?

• accelerating to the left of the diagram

• accelerating to the right of the diagram

• moving at uniform speed to the left of the diagram

• moving at uniform speed to the right of the diagram