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Question 1          (2+3=5 marks)

A tennis ball of mass 60.5g is hit straight up into the air at 45 . ms-1.

a) What is the initial kinetic energy of the golf ball?

b) What is the height to which the ball travels? “Ignore drag forces”.

Apply conservation of energy

Question 2               (2+1+2+1=6 marks)

a) Determine the change in momentum of the ball.

b) Find the net impulse that acts on the ball as it rebounds.

c) What is the average force that the wall exerts on the ball?

d) What is the average force that the ball exerts on the wall?

Question 3               (2+1+1+1+1=6 marks)

In a rear-end collision on a freeway, a car of mass 1500kg travelling east at 50 . ms-1 crashes into the back of a public bus of mass 9000kg heading east at 70 . ms-1. On impact the car and the bus are locked together.

a) Determine the final velocity and its direction of the car-bus system using conservation of momentum.

b) Calculate the total kinetic energy before the impact.

c) Calculate the total kinetic energy after the impact.

d) What type of collision is this?

Inelastic

e) How much energy transformed to another form?

Question 4 (3+2= 5 marks)

The roller-coaster similar to the one in the figure below is used to drag up a cart to level 1 where it is released from rest. Assuming no friction,

a) Determine the speed of the cart at level 2.

b) Calculate the speed at level 3.

Question 5                  (2+2+2= 6 marks)

A swimmer is swimming Vsw = 0.35 m.s-1 in still water. If she aims her body directly across a 300 m wide river whose current is Vws 0.25m.s-1

a) Calculate the velocity of the swimmer relative to the shore vss ”magnitude and direction”.

b) How far Δx downstream from a point opposite to her starting point will she land?

c) How long, in minutes, will it take the swimmer to reach the other side (constant velocity)?

Question 6 (3 marks)

A 5300W motor is used to lift building material weighing 1500 kg to a seventh story window, 15.8m above. Calculate the time it takes to lift the building material.

Question 7 (1+1=2 marks)

You have two springs that are identical except that spring 1 is stiffer than spring 2(k1

On which spring is more work done?

a) If they are stretched using the same force.

Spring 1 will stretch less, and so more work is done on spring 2.

b) If they are stretched the same distance.

It takes more force to stretch spring 1, and so more work is done on spring 1.

Question 8 (2+2= 4 marks)

The springs of a 250 kg truck compress 8.30 mm when its 75 kg driver gets into the driver’s seat.

a) Calculate the spring constant.

b) If the car goes over a bump. What will the frequency of vibrations be?

Question 9              (1+2= 3 marks)

A particular string resonates in seventh loops standing wave pattern at a frequency of 630 Hz.

a) Determine the fundamental frequency.

b) Name at least two other frequencies at which it will resonate.