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_________ can be a change in velocity and/ or direction
acceleration
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A dog chasing his tail is an example of what
acceleration
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A dog chasing his tail is doing what?
accelerating since his direction is changing
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What does the triangle (delta) mean
change in
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Acceleration is _______
speeding up
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Deceleration is _____
slowing down. can be called a negative acceleration
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What are the 4 vector quantities?
velocity, displacement, force, and acceleration
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Force and acceleration are what
are directly proportional
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Mass and acceleration are __
inversely proportional
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If an apple falls from a tree, why does it accelerate?
the falling object is effected by the pull of gravity
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A falling object is affected by the pull of gravity and we say the object is ___?
in free fall which only gravity is acting upon it
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What is gravity?
is an unbalanced force acting on the object, causing the object to change its velocity
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If all force are balanced and have a net force of 0 N what happens?
the object will not change speed or direction
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What is newtons 2nd law
States: the unbalanced force acting on an object equals the objects mass times its acceleration
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What does newtons 2nd law tell us
tells us how the unbalanced force will affect the movement of an object
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What else does the second law of newtons show
shows that acceleration and mass are inversely proportional to each other
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What are the 3 types of friction
rolling, fluid, and sliding
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The acceleration of an object is _________ related to the net force exerted upon it and ________ related to the mass of an object. In equation a=Fnet / m
directly, inversely
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If all forces are balanced on a moving object, what is true about the motion of the object and what is the value of the net force?
It is in equilibrium and have a net force of 0N and is in constant velocity.
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A cat experiences a net force of 5N. What would be the new force if the mass was tripled? ( the cat was really hungry)
2) What would the new force be if the mass was cut in half.
3) What would the new force be if the acceleration was doubled?
1) 15 Kg Work: (5) = m (1) . equation F=MA 5*3
2) 2.5 N
3) 10 N
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When Harry pulls with force P, 150 N, and the crate doesn't move, what is the magnitude of the friction f ?
> 150 N
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If the pulling force P increased to 200 N and the crate still doesn't move, what is the magnitude of F?
So when Harry pulls with 200 N, the crate is in ___?
>200 N
static equilibrium
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Harry increases his pull and the crate begins to slide. When he pulls with 250 N it slides at constant velocity. What is the magnitude of F?
When Harry pulls with 250 N the crate is in ______
250 N
dynamic equilibrium
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If the mass of the crate is 50 kg and sliding friction is 250 N, what is the acceleration of the crate when pulled with 250 N?
300N ____
250n______
500 N _____
- 250: No acceleration
- 300: 1 m/s2
500 : 5 m/s2
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An ant pulls a seed with a force of 0.2 N. Another ant pulls in the opposite direction with a force of 0.2 N. What is the net force?
0 N
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If a slingshot shoots a 0.1 kg marble at an acceleration of 50 m/s/s, what was the force that it applied
5 N forward
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If a bat hits a ball with a force of 40 N, and the ball's acceleration is 50 m/s/s, what is the mass of the ball in kg
0.8 kg
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A mule pulls a plow north with a force of 200 N. The sliding friction on the plow is 100 N. What is the net force ?
200-100 = 100 N north
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A dog pulls on its leash with 100 N towards the mailman. A boy pulls in the opposite direction with a direction with a force of 90 N. What is the net force
100-90 10 N toward the mailman
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what is the net force on a car at rest
0 N . balanced forces/ static equilibrium
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What is the net force on a car that is moving at a constant velocity
0 N . Balanced forces/ dynamic equibrium
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If an object has a net force of zero, what is the acceleration
0m/s2. No acceleration because at constant velocity
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What is the net force on a object with balanced forces?
0 N
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What two things can you say about an object's motion if the net forces on the object are zero?
constant speed in same direction
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If it takes 4 N of force to keep a shopping cart moving at a constant velocity , what is the force of friction on the cart?
constant velocity means 0 net force
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wHEN YOU PUSH something across the floor at a steady speed, you need to apply a force. Why?
Force is required to equal friction
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If you push a 10 kg wagon with a net force of 20 N, what is the acceleration?
20= 10(a)
2 m/s2
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The engine force of a car is greater than the force of friction. What can you say about the speed of the car?
engine force is greater than the force of friction
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The engine force and the force of friction on a car are balanced. What can you say about the speed of the car?
- engine force = force of friction
- speed constant
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Gravity pulls a statue on to its pedestal with a force of 345 N. What force is the pedestal exerting and in what direction
- gravity 345 N down ward
- balanced forces
- 345 N upward
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Two teams are playing tug of war. One team pulls north with forces of 10 N, 30 N, and 50 N. The other team pulls south with forces of 45 N and 52 N. What is the net force?
net force= 7 N south
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Two students are arm wrestling and neither is winning. One student is pushing with a force of 59 N. What is the force of the other student?
bALANCED FORCES IF NITHER IS WINNING 59 N
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