The University of ZambiaA-Level Training and Consultation Unit

AS Physics Unit1

Questions on Forces

1) A passenger of mass 70 kg is in a lift accelerating upwards at a rate of 1.5 m/s2. What force does he feel on his feet due to this acceleration?

2) A cyclist and a bicycle of combined mass 109 kg are travelling up a hill at a steady speed of 15 m/s, but using the maximum available force. With the force removed, they come to rest in 3.5 s.

a. Calculate the decelerating force. b. Assuming the forces remain the same, what is the maximum speed which

could be attained by cycling downhill from rest for 6.5 s?3) Explain why a skydiver has two different terminal velocities at different stages

during her jump?4) On a particular planet, a mass of 8 kg has a weight of 28 N. On another planet

with twice the gravitational field strength, what is the weight of a 16 kg mass?5) The diagram shows a block sliding down a plank at a constant speed.

a. What can you say about the forces?b. The weight of the block is 5 N and the plank is at an angle of 35o to the

horizontal. Sketch a vector diagram for the three forces and use it to calculate the friction.

Questions on Projectile motion

1) During a school production of MacBeth, a dagger is kicked and slides off the stage with an initial horizontal velocity of 1.5 m/s. It lands on the floor a horizontal distance of 80 cm away. Calculate the height of the stage.

2) Water from a garden hose at ground level is squirted into the air at an angle of 65o

to the horizontal. The water reaches a height of 2.5 m above the hose.a. Sketch the path of the water.b. By considering vertical motion only, Calculate the vertical component of

water’s initial velocity.c. Use the vertical component to find the horizontal component of the

water’s initial velocity.3) Find the distance travelled by a ball kicked from ground level at a speed of 12 m/s

and an angle of 33o to the horizontal.4) In the absence of air resistance, the maximum range is achieved for a launch angle

of 45o to the horizontal. By thinking about the effect of air resistance on vertically upward motion, vertically downward motion and the horizontal motion, draw and describe the path of a real projectile.

5) A ball is kicked off a flat roof with a horizontal velocity of 12 m/s. How would you

a. calculate the horizontal distance travelled after it has fallen 15m?b. calculate the resultant velocity after 1.9 s?