Laws of Motion and Forces ReviewName key

1. State Newton’s Three Laws of Motion

a.An object in motion will stay in motion until a force acts upon it, an object at rest will stay at rest until a force acts on it.

b. An objects acceleration is dependent upon the mass and the force applied to it.

c. Every action has an equal and opposite reaction

2. One morning on my way to school I stopped at a stoplight next to a big truck with foundation forms on it. When the light turned green we both began to accelerate. I, however, got to the otherside of the intersection before he did. I did not peel out, either.(I am a very safe driver). Explain why I reached the other side of the intersection before he did using newton’s second law of motion. The truck has more mass so it will take more force to accelerate it, and the car has less mass, so it will take less force to accelerate it. Therefore, the car will be easier to accelerate because it requires less force.

3. A few years ago on ER Dr. Ross’s car hit an ice patch and slid. He was unable to stop the car with the brakes. Explain why using Newton’s first law of motion and friction. The car was in motion, and an object in motion will stay in motion until a force acts on it. Since the road was icy, there is less friction than would be with no ice, and the car will have little to oppose its motion, so it will continue forward when he tries to apply the brakes.

4. Jeannie Boulet, the physicians assistant on ER, was in Dr. Ross’s car during the accident. She did not have her seat belt on and she hit the windshield. Explain why using Newton’s first law of motion. Her body continued in motion even though the car had stopped because it crashed.

5. When the Apollo missions were going to the moon, they had to burn their engine to get out of earth orbit, but then they shut the engine down as they traveled to the moon. Why were they able to reach the moon without additional propulsion? Use Newtons first law They were in motion and there were few forces to act against the motion so they stayed in a straight line on the way to the moon.

  1. Describe the forces that acted on your orange energy cars to slow them down?

Friction with track, with air

  1. What is the difference between speed and velocity?

Speed and velocity are both distance/time, but velocity includes direction

8. What is the difference between acceleration and velocity?

Acceleration is a change in velocity over time

9What is inertia? How is it affected by weight?

Inertia is an objects resistance to a change in motion

Drawings: In the following diagrams, draw arrows to show the forces involved in each one. Be sure to show forces of gravity, friction, and any other pushes or pulls.

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  1. Imagine you are driving home from the grocery store. In the back seat there is a case of Dr. Pepper and a bag of Doritos. What will happen to the case of Dr. Pepper and the bag of Doritos if you have to slam on your breaks suddenly? Use Newton’s 1st Law and Friction in your answer Both will continue forward due to inertia. The box will have more friction with the seat than the bag.
  1. Which one, the doritos or the Dr. Pepper, is more likely to fall off of the seat and why? Use Newton’s 1st Law or 2nd Law in your answer. . Dr. Pepper will have more momentum and more inertia, so it will be more difficult to stop, it will also have more surface area with the seat, so it will experience more friction. (but my bet is that the inertia will over come the friction) so the dr pepper will fall and the Doritos will not.
  1. What is friction? How does it affect motion? A force that opposes motion, between to surfaces in contact with each other.
  1. What is a force? How does it affect motion? A push or pull, that causes something to change its motion.
  1. What is velocity? How does it describe motion? Distance covered in a given amount of time along with direction, or speed with direction.
  1. What is acceleration? Change in velocity over time
  1. Describe the motion of a ball thrown through the air. Include the affects of gravity and the horizontal motion applied initially. Ball has horizontal (forward) motion and also vertical motion due to gravity. If ball has an upwards motion, that acts against gravity until it equals gravity, then it begins to fall down.
  1. Describe the effects of gravity on all falling objects. All objects fall at an equal rate on the earth 9.8 m/s2
  1. A car travels 80 miles in 20 minutes. What is its velocity in miles/min? 80/20=40 miles/minute
  1. A shopping cart travels 50 m in 30 seconds. What is its velocity in m/s?50/30, 1.666 m/s
  1. A ball has a mass of 10 kg. It is accelerated with 10 N of force. What is the acceleration of the ball? F/m=a 10 N/10kg = 1 m/s2
  1. A shopping cart has 50 kg of groceries in it. It is traveling 5 m/s and hits your brother in the back. How much force does it hit him with? F=m x a 5 x 50 = 250 N
  1. What is potential energy? Kinetic energy? How do they affect a roller coaster ride? Stored energy energy in use, or energy of motion PE at top of hill on coaster, KE at bottom of hill on coaster
  2. The human cannon is about to be fired. The human is put in the cannon, and the gas chamber is loaded with fuel. When the fuel ignites it will expand, and push the human out. What will the reactive force be on the cannon? It will push the cannon back
  1. Remember energy? What is the difference between potential energy and kinetic energy? PE is stored energy, KE is energy that is in motion
  1. What happens to all objects as they fall? How do they compare to each other? All fall at the same rate
  1. How does velocity compare to acceleration? Velocity is constant, acceleration is changing velocity
  1. What does a graph look like of someone at constant velocity?Straight line
  1. Draw two lines on the graph, one showing slow constant speed, one showing fast constant speed.

distance

time