MOMENTUM - ENERGY - MOMENT EXAM
Name and surname April 2006
Calculate the momentum of a golf ball of mass 50 g moving at 70 ms-1. (2 marks)
James accelerates in his car of mass 900 kg from rest to a speed of 12 ms-1 in a time 14 s. What is the net force acting on James' car? (3 marks)
A Holden Commodore of mass 1200 kg mov 10210g69k ing with a speed of 10 ms-1 runs into the back of a pizza delivery van of mass 850 kg which is initially at rest. The two vehicles loc together after impact. Calculate the speed with which the two vehicles move off together. (3 marks)
Using the concepts of impulse and momentum explain why thick safety mats enable pole vaulters to land on their backs with out sustaining injury. (4 marks)
Jim hits a baseball with his baseball bat. The force versus time graph for this interaction is shown below. Calculate the change in momentum of the baseball. (3 marks)
F (N)
|
t (s) |
If the mass of the baseball mentioned above is 200 g (0.2 kg) what is the change in velocity of the baseball
A loaded cannon with ball has a mass of 250 kg. What is the velocity of a 5 kg ball if the cannon moves backwards at 0.5 m/s? (2 marks)
A man pushes down on a lawnmower
with a force of 50 N at 55 degrees above the horizontal along the +x.
a) If the displacement is 6 m, how much
work does the man do on the lawnmower?
b) If the lawnmower starts from rest,
how fast is it moving at the end of the 6 m if its mass is 100 kg? (4
marks)
A crane pulls a 250 kg box 35 m upward with a constant speed in 5.5 seconds. Find the power used by the crane. (2 marks)
Suppose the crane in the problem above has a giant 400 kg ball at the end of a 15 m cable. If the ball is above the ground in such a way that the cable makes an angle of 25 degrees with the vertical, determine the speed of the ball when passing point M ( 3 marks )
The biceps muscle exerts a vertical force on the lower arm as shown in the diagram below.
a) For case (a) calculate the torque ( its moment ) about the axis of rotation through the elbow joint due to the weight of the lower arm and hand. Assume the muscle is attached 5.0cm from the elbow. Show your work. marks )
b) For case (b) calculate the torque about the axis of rotation through the elbow joint due to the weight of the lower arm and hand. Assume the muscle is attached 5.0cm from the elbow. Show your work. marks )
|
