HARD
AS and A Level
IMPORTANT
Earn 100

At the end of a downhill run, a skier of mass 80 kg slides up a rough slope at an angle of 10° to the horizontal, to slow down. He arrives at the upward slope with an initial speed of 12 ms-1. The coefficient of friction between the skier and the slope is 0.4. Find how far up the slope he comes to rest, and show that he remains at rest there without falling back down the slope.

Important Questions on Friction

HARD
AS and A Level
IMPORTANT

A book of mass 3 kg is at rest on a rough slope at an angle of 15° to the horizontal. It takes a force of 20 N parallel to the slope to break equilibrium and drag it up the slope.

Find the coefficient of friction between the slope and the book.

MEDIUM
AS and A Level
IMPORTANT

A book of mass 3 kg is at rest on a rough slope at an angle of 15° to the horizontal. It takes a force of 20 N parallel to the slope to break equilibrium and drag it up the slope.

Find the acceleration of the book down the slope if the 20 N force is applied down the slope.

HARD
AS and A Level
IMPORTANT

A box of mass 12 kg is at rest on a rough slope at an angle of 18° to the horizontal. The coefficient of friction between the slope and the box is 0.4.

Find the force it takes parallel to the upwards slope to break equilibrium and drag the box up the slope.

HARD
AS and A Level
IMPORTANT

A box of mass 12 kg is at rest on a rough slope at an angle of 18° to the horizontal. The coefficient of friction between the slope and the box is 0.4.

If the force were applied down the slope and parallel to it, find the acceleration.

HARD
AS and A Level
IMPORTANT
A car of mass 1250 kg is at rest on a rough slope at an angle of 35° to the horizontal. It takes a force of 13000 N to move it up the slope. Show that without any force the car would slide down the slope, and find the minimum force to prevent it moving down.
HARD
AS and A Level
IMPORTANT
A bin of mass 10 kg is at rest on a rough slope at an angle of 32° to the horizontal. It is held on the point of moving up the slope by a force of 90 N parallel to the slope. Show that when the force is removed the bin would slide down the slope, and find its acceleration.
HARD
AS and A Level
IMPORTANT
A trolley of mass 5 kg is rolling up a rough slope, which is at an angle of 25° to the horizontal. The coefficient of friction between the trolley and the slope is 0.4. It passes a point A with speed 12 ms-1. Find its speed when it passes A on its way back down the slope.
HARD
AS and A Level
IMPORTANT
A ball of mass 1.5 kg is sliding up a slope, which is at 30° to the horizontal. The coefficient of friction between the ball and the slope is 0.45. It passes a point A at 10 ms-1. By modelling the ball as a particle, find the time taken to return to A.