Term
| What keeps asteroids moving in space? |
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Definition
| Nothing keeps them moving. The Sun can deflect their path, but it isn't needed to keep them moving. |
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Term
| What does a car whiplash have to do with Newton's first law? |
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Definition
| Your head and body remains at rest, but when you move forward, only your back seat keeps you from moving, so the head will continue to move because of the force that is acted upon it |
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Term
| What law applies to when you move forward/backward on a bus when accelerating and why? |
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Definition
| Newton's first law because when the bus is at rest, you are at rest. So when the bus moves, you are being pulled with it and results in your body moving backwards. |
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Term
| What can you say correctly about a pair of vectors that add together to equal 0? |
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Definition
| The vectors are equal in magnitude and opposite in direction |
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Term
| A bird sits on a clothes line. Will the tension be greater if the line sags a little or a lot? |
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Definition
| A little because larger vectors are needed to support the weight of the bird. |
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Term
| Can an object be in mechanical equilibrium if a single non-zero force acts upon it? |
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Definition
| No because its motion will change |
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Term
| If you pull horizontally on a crate with a force of 200N, it slides across the floor in dynamic equilibrium. How much friction is acting upon the crate? |
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Definition
| 200 N (equal to your pull of -200N) |
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Term
| A parachutist is falling through the sky in dynamic equilibrium. How do the magnitude of the gravitational pull and air resistance compare? |
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Definition
| They're equal, so the net force is zero. |
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Term
| A ball rolling on the floor moves slightly slower over time. Does this violate Newton's first law? Why or why not? |
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Definition
| No, because the force of air resistance is acting up on it. If there was no force acting upon the ball, it will continue to roll. |
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Term
| Since the earth is moving, you move with it and won't hit the wall in your room. But when you jump, how come you don't hit the wall since the earth is still moving? |
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Definition
| Because your body is in motion so it will stay in motion. |
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Term
| Is a fine for speeding based on your instantaneous speed or your average speed? Explain |
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Definition
| Instantaneous speed because that's the speed registered on the speedometer gun the police are using. |
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Term
| Light travels in a straight line at a constant speed of 300,000 km/s. What is its acceleration? |
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Definition
| Zero because a constant velocity means no acceleration. |
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Term
You are driving on a highway, then w/o changing speed, you turn on a curve.
(a) Does your velocity change? (b) Do you accelerate?
Explain |
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Definition
(a) Yes, because of the change in direction
(b) Yes, because the velocity changes |
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Term
| For a free-falling object dropped at rest, what is the acceleration of the object after 5 seconds? After 10 seconds? |
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Definition
| The acceleration is the same as g (gravity) at any point in the fall because it is a free fall. |
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Term
| Suppose that a free-falling object is equipped with a speedometer. How much speed is increased with each second of the object falling? |
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Definition
| 10 m/s each second (because of gravity) |
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Term
| If there was no air resistance, why would it be dangerous to go outside when it's raining? |
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Definition
| If not for the slowing affect of air resistance, the raindrops will strike the ground with speed as high as bullets. |
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Term
| When a ball is tossed into the air with air resistance, how does the return speed compare with its initial speed? |
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Definition
| Air resistance decreases speed, so a ball will return with less speed than it did initially. |
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Term
| How does a speedometer indicate whether or not and object is accelerating? |
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Definition
| When the speed changes. No change = no acceleration |
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Term
| If gold was sold by weight, would you buy it in Death Valley or Denver? If it was sold by mass, where would you buy it? |
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Definition
| If by weight, buy it in Denver because the force of gravity is lesser there. If by mass, it would be the same price both places. |
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Term
| If your empty hand hits a wall, it will hurt less. But if you're holding an object and hit a wall, it will hurt more. Why? Which of Newton's laws applies here? |
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Definition
| Holding an object means there's more mass. More mass means there's more tendency to keep moving. Newton's first law. |
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Term
When blocking in football, a lineman wants to get lower than their opponent when pushing each other to lift them off the ground.
What effect does this have on the friction force between the opposing linemen's feet and the ground? |
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Definition
| Lifting the opponent decreases the force with which the ground supports him = decreases the force of friction he can muster. |
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Term
(a) Is a skydiver who has reached terminal speed in free fall?
(b) Is a satellite circling above Earth's atmosphere in free fall? |
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Definition
(a) No, because there is air resistance. Free fall means free of all forces except gravity.
(b) Yes, even though the satellite isn't getting any closer to Earth, it is still falling. |
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Term
| Two balls fall from the same height. One is filled with lead pellets. Which one will hit the ground first? Which one has a greater air resistance? |
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Definition
| The ball with lead pellets will hit the ground first. The ball with the lead pellets also has the greatest air resistance because it is falling much faster than the normal ball. |
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Term
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Definition
| The property of things to resist change in motion |
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Term
| What's Newton's first law of motion? |
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Definition
| An object at rest stays at rest unless acted upon by a force |
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Term
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Definition
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Term
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Definition
| The vector sum of forces acting upon an object |
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Term
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Definition
| An arrow that represents a vector quantity |
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Term
| What is a Vector Quantity? |
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Definition
| Having both magnitude and direction (Ex: force) |
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Term
| What is a Scalar Quantity? |
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Definition
| A quantity that has magnitude but no direction |
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Term
| What is an example of Scalar Quantity? |
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Definition
| Mass, volume, time, speed |
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Term
| What is an example of Vector Quantity? |
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Definition
| Force, velocity, acceleration |
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Term
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Definition
| The net result of a combination of 2 or more vectors |
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Term
| What is Mechanical Equilibrium? |
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Definition
| When the net force on an object is zero |
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Term
| What is the Equilibrium Rule? |
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Definition
|
On an object or system of objects in mechanical equilibrium, the sum of forces = zero (∑F = 0) |
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Term
| What relationship between the Earth and the Sun did Copernicus formulate? |
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Definition
| That the Earth revolves around the Sun, not the other way around |
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Term
| What did Galileo discover in his Leaning Tower of Pisa experiment? |
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Definition
| Objects with different weight still hit the ground at the same time |
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Term
| How fast are you moving relative to the Sun? |
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Definition
|
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Term
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Definition
| How fast an object moves; the distance traveled per unit of time |
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Term
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Definition
| The total distance traveled divided by time of travel |
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Term
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Definition
| An object's speed and direction of motion |
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Term
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Definition
| The rate at which velocity changes with time |
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Term
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Definition
| Motion under the influence of gravity only |
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Term
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Definition
| A push or pull exerted on an object |
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Term
| What is Force measured in? |
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Definition
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Term
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Definition
|
The force that normally opposes the motion of an object |
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Term
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Definition
| The amount of matter in an object |
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Term
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Definition
| Force due to gravity on an object |
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Term
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Definition
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The point where the resistance of air matches the pull of gravity |
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Term
| Is acceleration proportional to the net force, or does acceleration equal net force? |
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Definition
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Term
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Definition
| When force is applied to an object but it doesn't move |
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Term
| What is Kinetic Friction? |
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Definition
| When force is applied to an object and it moves |
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Term
| What affects the amount of air resistance (3)? |
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Definition
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Term
| What is Earth's gravitational pull? |
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Definition
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Term
| What is the moon's gravitational pull? |
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Definition
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