Force
Gravity & Friction
Gravity/Newton's 1st & 2nd Laws
Newton's 3rd Law
Rockets & Satellites
100
What are 2 ways force is described?
strength & direction
100
11. What is Gravity? What is Universal Gravitation?
Gravity: the force that pulls objects together Universal Gravitation: everything is attracted to everything else
100
What is inertia?
an object's resistance to a change in it's movement
100
20. What are the two most common forces on Earth that change an object’s motion?
gravity friction
100
What is the difference between a satellite and an artificial satellite?
A satellite is any object that orbits another object in space. An Artificial satellite orbits another object in space, however, it is launched into orbit.
200
Explain why when you walk into the classroom the force you exert on the door is different than when you walk out of the classroom.
The direction of the force changes (and possibly the strength)
200
12. What can affect the strength of gravity?
mass of the objects distance between the objects
200
15. What happens as an object free falls? Why?
the object accelerates because gravity creates an unbalanced force on the object.
200
What is momentum and how does it relate to a person stopping a car vs. stopping a baseball?
Momentum- the amount of motion something has The greater the mass of an object, the more momentum it has. The more momentum something has the harder it is to change its motion. This means a person can stop a baseball, but not a car.
200
What is Centripetal Force?
The force that causes objects to move in a circular path.
300
5. What is the difference in motion between a box with balanced forces and a box with unbalanced forces?
the box with the balanced forces will not move the box with the unbalanced forces will move
300
17. If all objects accelerate at the same rate during free fall, why don’t they land at the same time? Explain.
Objects do not land at the same time because they have different surface areas and air resistance affects them differently. greater surface area=greater air resistance=falls slower smaller surface area=less air resistance=falls faster
300
What are Newton's 3 Laws of Motion?
1. An object in motion tends to stay in motion, and an object at rest stays at rest, until acted upon by an outside force. 2. Force equals mass times acceleration. 3. For every action there is an equal and opposite reaction.
300
What does the Law of Conservation of Momentum state?
the total momentum a group of objects has is will remain the same unless acted on by outside forces (momentum will not be lost in a collision)
300
Explain how inertia can be shown by a car stopping short.
As you ride in a car your body is moving forward. When the brakes cause your car to stop short, you lurch forward until the seat belt stops you. You lurching forward demonstrates inertia. Your body is resisting the change in motion (moving forward-stopping).
400
Define Force AND Net Force.
Force: a push or pull Net Force: the overall force exerted on an object
400
9. What are the 4 types of friction? Give an example of 2 of them. Bonus 100 points if you can give an example for all 4.
Static: when you go to push a box across the floor (box/floor) Sliding:when you sled down a hill (sled/hill) Rolling:when you roller blade (wheels/ground) Fluid: when you surf (surfboard/water)
400
16. On Earth, at what rate do all objects accelerate during free fall?
9.8 meters per second per second
400
If a yellow 5kg car going 6m/s hits a still purple 5kg car, what will happen to the 2 cars after they collide?
The yellow car will stop moving and the purple car will move at a rate of 6m/s. (all of the momentum was transferred from the yellow car to the purple car)
400
How do rockets demonstrate Newton's Third Law of Motion?
As the rocket burns fuel it pushes the exhaust downward. The exhaust then pushes back at the rocket with equal, but opposite force.
500
4. Mrs. Desir-Lewis pushes a box with 50N. Miss Houde helps her and pushes with 50N. Mr. Miller exerts a force of 95 newtons on the box in the opposite direction. What is the net force exerted on the box? What direction will the box move in? Draw a picture with arrows to represent the forces.
The net force will be 5N in the direction that Mrs. Desir-Lewis & Miss Houde are pushing. The box will continue to move in that direction.
500
13. 14. What is the difference between weight and mass? With this in mind explain what changes when you go to the moon and why.
Mass-amount of matter something has Weight-the force of gravity on something When you go to the Moon the gravitational force changes. In turn this changes your weight. Your mass will stay the same because the amount of matter that makes you does not change.
500
Define the following: Velocity Terminal Velocity Projectile Air Resistance Free Fall
Velocity- speed in a given direction Terminal Velocity- the greatest velocity a falling object reaches Projectile- an object that is thrown Air Resistance-the upward force exerted on all objects Free Fall- when the only force acting on an object is gravity
500
What happens when a pink train moving 10m/s hits a still orange train and they connect?
The mass of the object being moved changes. This causes the pink train to move at 5m/s and the orange train to move at 5m/s. The momentum was shared...not lost.
500
Explain why a satellite does not fall back to Earth? What are the forces acting on the satellite and in what direction are they pulling the satellite.
The satellite is being pulled to Earth by gravity, and at the same time its inertia is pulling it out towards space. This creates centripetal force on the satellite, causing it to orbit the Earth in a circular pattern. It does not fall back to Earth because the Earth curves underneath it and if it does try to fall it misses the Earth.
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