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Physics 1: Unit 6 – Energy Answer the following 20 questions

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Physics 1: Unit 6 – Energy Answer the following 20 questions. You do not need to show your work! 1. The following diagram shows the path of a projectile. At what point does the pendulum have the highest gravitational potential energy? Select one: a. Position A and C are equivalent. b. Position B c. Position A d. Position C 2. The following diagram shows the path of a projectile. At what point does the pendulum have the highest kinetic energy? Select one: a. Position A b. Position B c. Position A and C are equivalent. d. Position C 3. Two identical cars, A and B, are travelling down the highway. A is moving at 30 m/s and B is moving at 15 m/s. Both brake until their speeds are 0 m/s. How will the temperature of their brakes compare? Select one: a. Neither will change temperature. b. They will have the same positive temperature change. c. A's temperature change will be four times that of B. d. They will have the same negative temperature change. e. A's change in temperature will be twice as big as B's. 4. The diagram below shows 3 possible forces, each having the same horizontal magnitude on a box that is moving to the right. Which force would be doing the most amount of work on the box? Select one: a. Force C b. Force B c. Force A d. All 3 are identical. 5. Which statement best describes what happens to energy when one moving cart hits a second stationary cart (of the same mass) and they both move off at half the original speed? Select one: a. The energy of the system increases as two carts are moving after the collision, compared to one before. b. The energy of the system decreases as the carts are moving slower after collision than before. c. The energy of the first cart decreases as the energy of the second cart increases. 6. An athlete bench presses 60 kg, 1.0 m off their chest. How much gravitational potential energy does the weight have? Answer:___________________________________ 7. A 1.0 kg ball is moving at 15 m/s. How much kinetic energy does it have? Answer:___________________________________ 8. A glass of 50 g of water (C = 4.184 J/g°C) goes from 25 to 30 °C. How much thermal energy was put into it? Answer:___________________________________ 9. 100 N of force is used to pull a 50 kg wagon 3.0 m. How much work is done on the wagon? Answer:___________________________________ 10. 1.0x103 J of energy is expended throwing an 8.0x101 kg hay bale straight up into the air. How high will the hay bale go? Answer:___________________________________ 11. A 1,000 kg car has 10,000 J of kinetic energy. How fast is it going? Answer:___________________________________ 12. 200 J of energy are put into a 100 g block of aluminum (C = 0.90 J/gC). What is the temperature change of the block of aluminum? Answer:___________________________________ 13. A 75 kg student in a wheelchair is pushed 5.0 m. If the students kinetic energy changes by 250 J, what is the average force used to push the student? Answer:___________________________________ 14. A 1,000 kg roller coaster starts from rest at the top of a 20.0 m tall hill. How fast will it be going at the bottom of the hill assuming no friction? Answer:___________________________________ 15. A student is riding their bike (combined mass 85 kg) at 10.0 m/s at the bottom of a 2.0 m tall hill. They have 10.0 m of level surface before the hill begins. How much force will have to be put on the bike over the level surface in order for it to coast up the hill and still be going 9.0 m/s at the top? Answer:___________________________________ 16. A 3.0 kg ball of dough (C = 3.5 J/kg°C) is dropped from 1.0 m above the ground. When it hits the ground it flattens out and stops. What is the temperature change of the dough ignoring energy that goes into changing the dough's shape? Answer:________________________________________ 17. A child and sled (combined mass 35 kg) are going down a hill that is 4.5 m tall and runs for 35 m. If the the child starts at rest, how fast will they be going at the bottom of the hill if the force of friction on the child is 40. N? Answer:________________________________________ 18. An unknown metal with a mass of 150 g is taken out of boiling water (100 °C) and placed into 120 g of water(4.184 J/g°C) that starts at 25 °C. If the two come to a final temperature of 31°C, what is the specific heat of the metal? Answer:_________________________________________ 19. A 0.010 kg marble is going along a track at 8.0 m/s. The track is inclined upward and the marble stops moving when it is 2.2 m off of the ground. How much energy was lost due to friction? 1/2*0.01*8^2 = W + 2.2*9.8*0.01 Answer:_____________________________________ 20. A 0.015 kg bullet is moving at 350 m/s an goes into a foam block. If the bullet goes 3.2 meters into the foam block before stopping, what is the average force on the bullet? 1/2*0.015*350^2 = 3.2*F Answer:_____________________________________