Download 1. Whats your weight on a planet which has the same radius as the

1. Whats your weight on a planet which has the same radius as the Earth but is twice
its mass? What about your mass?
1a. Mass the same but weight increased by a factor of two.
2. Whats your weight on a planet which has the same radius as the Earth but is three
times and then four times the mass? What about your mass?
2a. Mass the same but weight increased by factors of 3 and 4 respectively.
3. Whats your weight on a planet which has the same mass as Earth but twice its radius?
3a. Weight reduced by a factor of 4. Mass the same.
4. Whats your weight on a planet which has the same mass as Earth but three times
and then four times its radius?
4a. Weight reduced by factors of 9 and 16 respectively. Mass the same.
5. Whats your weight on a planet which has twice the mass as Earth and twice the radius
of Earth? What about mass?
5a. Weight reduced by a factor 2/4 = 1/2. Mass the same.
6. Whats your weight on a planet which has 3 times the mass of Earth and 4 times the
radius of Earth? What about mass?
6a. Weight reduced by a factor of 3/16. Mass the same.
7. A force of 10N acts on a mass of 5kg. What acceleration is produced?
7a. Use F = m × a. So a = F/m = 10/5 = 2m/s2 .
8. What force is need to produce an acceleration of 5m/s2 for an object of mass 20kg?
8a. It is F = 5times20 = 100N ewtons.
9. A force of 20N acts on an object and produces an acceleration of 2m/s2 . Whats the
mass of the object?
9a. It is mass = F orce/acceleration = 20/2 = 10kg.
10. A car of mass 1000kg moves with a velocity of 20m/s. What is its energy? Get the
units of energy correct.
10a. It is Kineticenergy = 0.5 × mass × (speed)2 . So its 0.5 × 1000 × 202 = 200000Joules.
11. What happens to this energy if the speed is doubled, tripled and quadrupled?
11a. Kinetic energy (KE) is increased by a factor of 4, 9 and 16 respectively.
12. Is this kinetic energy or potential energy?
12a. This is Kinetic Energy.
13. Which has more potential energy: a car at the bottom of a hill or a car at the top of
a hill?
13a. Car at the top of a hill.
14. Which has more potential energy: a car at the top of the Adirondacks or a car at the
top of Mt. Everest.
14a. Car at the top of Mt. Everest.
15. Which has more potential energy: a car at the top of Mt. Everest or a car on the
Moon.
15a. Car on the Moon.
16. You throw a ball in the air. When does it have the greatest kinetic energy and when
does it have the greatest potential energy?
16a. Greatest KE when it leaves your hand or returns to your hand. Greatest PE at the
top of the arc.
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17. In ideal situation, does the total energy of the ball change at any time during the
throw?
17a. Total energy = PE + KE = constant, so No.
18. In terms of the movement of the water molecules, whats the difference between a cold
bucket of water and a hot bucket of water?
18a. Water molecules on averaqge move faster in the hotter bucket.
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