Newton's Laws of Motion (CIE AS Physics)

A car has a horizontal driving force of 2.0 kN acting on it and a resistive force a quarter of this size. It has a forward horizontal acceleration of 2.0 m s^–2

What is the mass of the car?

All external forces on a body cancel out.

Which statement must be correct?

A stone of mass m is dropped from a tall building. There is significant air resistance. The acceleration of free fall is g.

When the stone reaches its terminal velocity, which information is correct?

	Magnitude of the acceleration of the stone	Magnitude of the force of gravity on the stone	Magnitude of the force of air resistance on the stone
A B C D	zero g g zero	mg mg zero zero	mg mg zero zero

A ball falls vertically and bounces on the ground

The following statements are about the forces acting while the ball is in contact with the ground

Which statement is correct?

A wooden block rests on a rough board. The end of the board is then raised until the block slides down the plane of the board at constant velocity v

Which row describes the forces acting on the block when sliding with constant velocity?

	Frictional force on block	Resultant force on block
A B C D	down the plane down the plane up the plane up the plane	zero down the plane zero down the plane

The acceleration of free fall on planet X is    of the acceleration of free fall on Earth.

The mass of a body on planet X is 60 kg.

What is its weight on planet X?

A block of mass 1.20 kg is on a rough horizontal surface. A force of 12 N is applied to the block and it accelerates at 4.0 m s⁻²

What is the magnitude of the frictional force acting on the block?

Newton’s third law of motion is often summarised as 

   ‘Every action has an equal and opposite reaction.’

A cup of tea rests on a table. If the weight of the cup is the ‘action’ force, what is the ‘reaction’ force?

The gravitational field strength on the surface of planet R is one eighth of that on the surface of planet S.

On the surface of R, a body has its mass measured to be 2.5 kg and its weight measured to be 12.5 N

What results are obtained for measurements of the mass and weight of the same body on the surface of planet S?

	Mass on S	Weight on S
A B C D	2.5 kg 20 kg 2.5 kg 20 kg	20 N 100 N 100 N 160 N

Water is pumped through a hose-pipe at a rate of 80 kg per minute. It emerges from the hose-pipe horizontally with a speed of

Which force is required from a person holding the hose-pipe to prevent it moving backwards?

A box of mass 10.0 kg rests on a horizontal rough surface. A string attached to the box passes over a smooth pulley and supports a 4.0 kg mass at its other end.

When the box is released, a frictional force of 12.0 N acts on it.

What is the acceleration of the box?

A lift consists of a passenger car supported by a cable which runs over a light, frictionless pulley to a balancing weight. The balancing weight falls as the passenger car rises.

Some masses are shown in the table.

 

	Mass / kg
passenger car balancing weight passenger	1200 1320 80

 

What is the magnitude of the acceleration of the car when carrying just one passenger and when the pulley is free to rotate?

A 3.2 kg mass is supported by a person’s hand and two newton-meters as shown.

When the person’s hand is removed, what is the initial vertical acceleration of the mass?

A brick of mass 1.8 kg rests on a plane inclined at an angle of 30°. The weight of the brick has a component of F N parallel with the plane. The brick also experiences a frictional force of 3.0 N 

What is the acceleration of the brick down the plane?

Two blocks X and Y, of masses m and 4 m respectively, are accelerated along a smooth horizontal surface by a force F applied to block X as shown

What is the magnitude of the force exerted on block Y by block X during this acceleration?

The three forces acting on a hot-air balloon that is moving vertically are its weight, the force due to air resistance and the upthrust force.

The hot air balloon descends vertically at constant speed. The force of air resistance on the balloon is F.

Which weight of material must be released from the balloon so that it ascends vertically at the same constant speed?

A ship of mass 6.7 × kg is approaching a harbour with speed 18.9 m s⁻¹

By using reverse thrust it can maintain a constant total stopping force of 880,000 N

How long will it take to stop?

A tennis ball is dropped onto a table and bounces back up. The table exerts a force F on the ball.

Which graph best shows the variation with time t of the force F while the ball is in contact with the table?

A skydiver falls vertically from a stationary balloon. 

She leaves the balloon at time t = 0. At time t = T, she reaches terminal velocity. Beyond the time shown in the graphs, she opens her parachute

Which graph shows the variation with time t of the force F due to air resistance?