SAMPLE: Test #3 Energy and Momentum (SPH 4U1) Name:______
Part A: Multiple Choice (Answer with the best choice):
1. Which of the following demonstrates zero work,
a. Carrying a stone at constant speed across a horizontal surface.
b. Pushing a stone perpendicular to its forward velocity.
c. Pushing against a building.
d. None of the above.
e. All of the above.
2. A 1.30 kg pendulum bob is pulled to the side, raising it 19.0 cm above its rest position. After it is released, the maximum speed will be,
a. 0.616 m/s b. 1.93 m/s c. 3.72 m/s d. 6.16 m/s e. 37.2 m/s
3. A person runs at a constant speed up a slope that is angled at 12 degrees to the horizontal. At one point, he is 3.2 m vertically above the bottom of the hill. To double the gravitational energy compared to the 3.2 m level of the hill, the runner must run an additional (up the slope)
a. 0.66 m b. 1.6 m c. 3.2 m d. 6.4 m e. 15 m
4. A moving curling stone, A, collides head on with a stationary stone, B. Both stones are of identical mass. If friction is negligible during this elastic collision,
a. Stone A will slow down
b. After the collision, the momentum of stone B will be less than that of stone A
c. Both stones will come to rest shortly after the collision
d. After the collision, the kinetic energy of the stone B will be less than that of stone A
e. After the collision, stone A will have a speed of zero.
5. For an inelastic collision which of the following statements is true,
a. Potential energy before equals the potential energy during and after.
b. Kinetic energy before equals the kinetic energy after.
c. Potential energy before is greater than the potential energy after.
d. Potential energy before is less than the potential energy after.
e. Kinetic energy before is less than the kinetic energy after.
6. Which of the following will be the easiest to accelerate to a certain angular velocity,
a. A merry go round (carousel) with 10 people standing in the centre.
b. A merry go round (carousel) with 10 people standing on the outside edge.
c. A merry go round (carousel) with 10 people standing randomly throughout.
d. It makes no difference where they stand.
e. A merry go round (carousel) with 5 people standing in the centre and 5 people standing on the outside edge.
7. How far above the surface of Earth do you need to go for g to be reduced to 0.5 of its value on the surface of Earth?
a. 0.41 rE b. 0.5 rE c. 0.71rE d. 1.4 rE e. 2.0 rE
8. The mass of Neptune is 1.03 x 1026 kg. If g = 13.80 N/kg on the surface of Neptune, the radius of Neptune is
a. 5.38 ´ 106 m b. 6.38 x 106 m c. 2.23 x 107 m d. 2.65 x 107 m e. not enough info.
9. Three satellites are to be placed into a circular geosynchronous orbit (each will have a period of 24 hours) around the earth. The masses of the satellites are m1, m2, and m3. If m1>m2>m3 then the relationship between their orbits’ radii is:
a. r1>r2>r3 b. r1=r2=r3 c. r1<r2<r3 d. cannot be determined e. r1<r2>r3 OVER…..
10. Three children (two with a mass of 50 kg and one with a mass of 40 kg) are standing on a cart with a mass of 60kg. All three jump off at the same time each with a velocity of 5.0 m./s relative to the cart. Assuming no friction, what is the velocity of the cart after all of the children have jumped off?
a. 5.0 m/s [back] b. 2.5 m/s [back] c. 3.0 m/s [back] d. 3.5 m/s [back] e. 2.0 m/s [back]
Part B: Full Solution. Each question is worth 5 marks.
1. A truck of mass 3000 kg, moving at 5.0 m/s on a level, icy road, bumps into the rear of a car moving at 2.0 m/s in the same direction. After the impact the truck has a velocity of 3.0 m/s and the car a velocity of 6.0 m/s, both forward.
a. What is the mass of the car?
b. Calculate the total kinetic energy before and after the collision.
c. Was the collision elastic?
2. A block with a mass of 50kg is initially at rest on a horizontal floor. The floor has a coefficient of friction of 0.2. If the box is moved a distance of 40m by a man applying a constant force of 200N at an angle of 30 degrees above the horizontal, determine
a. The work done by the man
b. The work done by the block on the floor
c. The velocity of the block at the 40m point
3. A 2 kg block slides down a ramp (friction is negligible) inclined at 15 degrees to the horizontal onto a spring of force constant 5.0 x 102 N/m. The spring is compressed a distance of 0.1m before the block stops. Fine the distance the block slides down the ramp.
4. A 30kg girl goes down a slide at an amusement park, reaching the bottom with a velocity of 2.5 m/s. The slide is 10.0 m long and the top is 4.0 m above the bottom, measured vertically.
a. What is her gravitational potential energy at the top of the slide, relative to the bottom?
b. What is her kinetic energy when she reaches the bottom?
c. How much energy is lost due to friction?
d. Calculate the average frictional force acting on her as she goes down the slide.
5. A 1.0 kg air puck moving across a level table at 0.24 m/s approaches head-on a stationary air puck of mass 0.5 kg. If the collision is repulsive and elastic find:
a. The velocity of each puck after the collision
b. The velocity of both pucks when the masses are closest to each other
c. The total kinetic energy at minimum separation
d. The maximum potential energy stored in the magnetic force field during the collision.
6. A 4025 kg spacecraft (including the astronauts) is in circular orbit 256 km above the lunar surface. If the radius of the moon = 1.738 x 106 m and mass of moon = 7.36 x 1022 kg, determine
a. The kinetic energy of the spacecraft
b. The total orbital energy of the spacecraft
c. The binding energy of the spacecraft
d. The speed required for escape
e. The energy needed to move the satellite from the 256 km orbit to an orbit of 400 km above the lunar surface.
7. A jet engine intakes air in the front and mixes it with fuel. The mixture burns and is exhausted from the rear of the engine. Use the concept of momentum to explain how this process results in a force on the airplane that is directed forward. (communication question)
Multiple choice answers
EBEEAAACBD
ANSWER to #1
a. 1.5 x 103 kg b. 4.1 x 104 J both c. elastic
Answer to #4
ANSWERS 1.2 c 103 J, 94J, 1.1 x 103 J, -1.1 x 102 N
Answer to #5
a. 0.080 m/s, 0.32 m/s
b. 0.16 m/s
c. 1.9 x 10-2J
d. 9.6 x 10-3J
ANSWER to #6
b. 4.96 x109J
c. -4.96 x 109 J
d. 4.96 x 109 J
e. 2.22 x 103 m/s
f. 3.39 x 108J
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