Physics Chapter 12 - Picture Problems
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Back - Answer |
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| 1. Gravity: Why does the ball on the right hit the ground at the same time as the one on the left? |
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1. Even though the ball on the right has a forward trajectory, it is still pulled down to the ground at 9.8 m/s/s. Thus, both ball bearings hit the ground at the same time. | |
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2. Gravity: Why does the larger mass ball hit the ground at the same time as the smaller one? |
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2. Gravitational acceleration affects all objects the same way, regardless of mass. | |
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3. Forces: The energy of the bat is transferred into the ball. What Law does this illustrate? |
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3. This is called the Law of Conservation of Momentum. The momemtum of the bat is transferred directly into the ball. | |
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4. Forces: What is the total forward force acting on the car in this picture? |
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4. 10N - 7N = 3N The car has 3 newtons of forward force. |
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5. Forces: What is the total forward force acting on the car in this picture? |
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5. 10N + 10N = 20N (green vectors added together) 20N - 7N = 13N (Total green minus purple = remaining) The car has 13N of forward force. |
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6. Orbital Motion: a) What is the FORCE? b) What is the MOTION? |
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6. Orbiting is projectile motion. a) The FORCE is free fall or the gravitational attraction of the Earth. b) The MOTION is the forward movement of the object. Note: if the object's speed is not sufficient, free fall will take over and the object will be drawn closer to the planet. | |
| 7. Forces: Will the box move to the right or to the left? Why? |
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7. LEFT: The box will move to the left because the size of the vector arrow on the right is greater, therefore, there is a larger force pushing against the box on the right than on the left. | |
| 8. Forces: Which way will the column move? ... to the right or to the left? Why? |
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8. RIGHT: The force to the right is 20N greater than the force to the left. | |
| 9. Forces: a) If each arrow represents 10N of force on the box, what is the total force exerted on the box? b) Are these balanced or unbalanced forces? Why? |
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9. a) 20N (add them together) b) UNBALANCED (there is no opposing force of 20N on the opposite side of the box.) |
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| 10. Forces: Are these balanced or unbalanced forces? Why? |
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10. BALANCED (both vector arrows are the same length and they are exerting forces on opposite sides of the box) | |
| 11. Forces: If the plane is moving forward with 85N of force, but a head wind is exerting 100N of force on the plane, is the plane going forward or backwards? By how much? |
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12. BACKWARDS: 100N - 85N = 15N backwards | |
| 13. Forces: Are these forces balanced or unbalanced? Why? |
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13. UNBALANCED (The forces are not equal and they are not opposite in direction.) | |
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Weekend Trip: a) What is the total distance traveled? b) What is the average speed? c) Which leg was the fastest? (Q,R,S,T) |
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14. a) 14km + 12km + 15km + 11km = 52km b) 12min + 8min + 9min + 15min = 44min S = ? D = 52km T = 44min S = D / T S = 52km / 44min S = 1.18 km/min c) S at 1.6 km/min |
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| 15. Trajectory: Why does the ball follow a curved path? |
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15. Because gravity is acting on the ball at 9.8 m/s/s downwards. | |
| 16. Arm Wrestling: Their arms are locked in the 12 o'clock position. Describe what is happening in terms on one of Newton's Laws of Motion. |
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16. 1st Law: An object at rest will stay at rest unless acted upon by an outside force. Neither person can overcome the force of the other, so the forces are balanced & the hands are motionless. 2nd Law: Each person must exert more FORCE in order to win the contest. 3rd Law: The ACTION is the pressing of the hand against the opponent's hand. The REACTION is their elbows slipping out from underneath their arm. |
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| 17. Hot Air Balloons: The balloons are released and drift up in the air. Describe what is happening in terms of one of Newton's laws of motion. |
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17. They will continue moving up in the air until acted upon by an outside force -- Newton's First Law. | |
| 18. Roller Coaster Corners: If you are not strapped into the car, you will be flung out of the coaster car when it hits the turn. Why? |
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18. Even though the car does not necessarily change its speed as it goes through the turn, it is changing directions. Therefore, acceleration occurs and anything not strapped into the car will be thrown out of the car in a straight line parallel to the direction of travel at the instant it leaves the car. | |
| 19. Newton's Cradle: If you pull out the steel ball on the left, what will happen when it swings back to the waiting 5 balls? |
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19. As you swing the left ball out and let it go, it will swing back and transfer its momentum into the waiting 5 balls. The energy of momentum moves through each ball so that when it gets to the end, the 5th ball will swing out just like the first one did. | |
| 20. Tossing a coin in a moving airplane: The plane is cruising at 500 miles/hr. You toss a coin up in the air. Where does it land and why? |
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20. Because the coin also is going forward at 500 miles/hr it will come right back to your hand. Try this in a car! | |
| 21. Seat Belts: Use the concept of INERTIA to explain why you are required by law to wear a seat belt in an automobile. |
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21. When the car stops suddenly, your inertia (resistance to change in motion) causes you to continue moving at the speed the car was traveling BEFORE it slowed down quickly. Without the seat belt, you would be thrown through the windshield. So, to protect people from being killed in this way in automobile collisions, seat belts help your body slow down safely along with the rest of the car. | |
| 22. Washing Machine: When the water is drained out and the spin cycle starts, why does the spinning drum cause the clothes to become less wet? |
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22. T he spinning drum has holes in it. As the drum spins, the clothes are accelerated against the inside of the drum. The clothes can't get out because they are too big to go through the holes. Water, however, can get through the holes and is accelerated away from the clothes. The faster the drum spins, the less water is left on the clothes at the end of the spin cycle. | |
| 23. Vectors: List the forces at A, B, C, & D. |
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23. A : gravity B: Forward motion (action) D: Forward motion (reaction) C: Friction (fluid friction of the canoe against the water) |
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| 24. Vectors: List the forces at A, B, C, D, E, F, G, & H. |
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24. A & D: Forward Motion (action of pulling the rope away from opponent) B: & C: Gravity E & H: Friction (sliding friction of feet against ground) G & F: Forward motion (reaction of feet sliding towards opponent) |
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| 25. Vectors: List the forces at A, B, & C. |
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25. A : Gravity B: Forward motion (box being pushed to the right) C: Friction (acting in a direction opposite to the motion) |
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| 26. Vectors: List the forces for A, B, & C |
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26. A : Fluid Friction (air resistance) B: Forward motion of baseball C: Gravity |
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| 27. Vectors: List the forces at A, B, C, & D. |
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27. A : Gases & Exhaust coming out of the bottoom of the rocket (action) B: Gravity C: Fluid friction (air resistance) D: Forward Motion of rocket (reaction) |
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| 28. Vectors: List the forces at A, B, & C. |
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28. A: Gravity B: Forward Motion C: Sliding Friction (acting in a direction opposite to the motion) |
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| 29. Vectors: List the forces at A, B, & C. |
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29. A : Forward motion (of projectile leaving the rifle) B: Gravity C: Forward motion of rifle (reaction -- this is called "Kick Back" on a powerful gun.) |
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| 30. Identifying forces: What is the name of the FORCE that acts in the opposite direction to the forward motion of the car? |
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30. Friction of two types: Rolling friction on the tires and Fluid friction on the car itself. | |
| 31. Vectors: List the forces at A, B, & C. |
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31. A: Gravity B: Forward motion C: Friction -- air resistance |
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| 32. Vectors: List the forces at A, B, & C. |
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32. A: Friction -- rolling friction B: Gravity C: Forward motion |
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| 33. Space Shuttle: Two forces are acting on the space shuttle to keep it in orbit. What are the forces? |
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33. Forward motion and Free Fall (gravity) | |
| 34. Trampoline: If conservation of momentum is true, how could the boy's second jump be higher than his first jump? |
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34. He has to put MORE energy or force into the second jump or it will be the same height as the first. | |
| 35. Gravitron: The cylinder spins up & then the floor drops down. The two boys do NOT fall down. After reaching a constant speed, describe what is happening in terms of SPEED, VELOCITY, and ACCELERATION. |
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35. SPEED is constant once the gravitron spins up. VELOCITY is constantly changing because direction is constantly changing. ACCELERATION is constant because velocity is constantly changing directions. |
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36. There's water in that cup flying around your head. |
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36. a) The water is being accelerated into the bottom of the cup. As long as you spin the cup, it will not fall out. b) An object is accelerating when it changes direction c) Centripetal motion (objects moving in a circular motion) |
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37. Cruising Car with Balloon Inside: You're inside the car as it moves along at 45 miles per hour. You release a helium balloon and it floats to the ceiling of the car.. |
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37. a) At a sudden stop, the balloon will float to the front of the car because of INERTIA. The car is slowing down but the balloon is not, so it continues at the faster speed. b) Upon acceleration, the balloon will float to the back of the car because of INERTIA. Note: The car is going faster, but it is not, so it continues at its slower speed. |
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