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Force, Work, and Energy Quiz Physics
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Gravity
Terms in this set (20)
energy
the ability to cause change
energy
the ability to do work
Joules (J)
What unit is energy expressed in?
1 J = 1 N * 1 m
What does 1 J equal in Newtons?
Work
the scalar dot product between force and displacement, (energy and work are scalar, they do not have a direction)
it is found by multiplying the force times the displacement and the result is energy W = F (change in x)cos0
How is Work found?
when the applied force and the displacement are parallel, the cosine function is not necessary
When can Work be positive?
when the applied force and the displacement are in opposite directions, the cosine function is not necessary if you REMEMBER that this means negative work can be done
When can Work be negative?
when the applied force and the displacement are perpendicular, no work is done, in this case, the applied force doesn't contribute to the motion in any way
When can Work be zero?
when the force is applied at an angle with respect to the displacement, the cosine function must be used
What happens when forces are applied at angle?
They equal each other
What is special about net work and the change in kinetic energy?
K=1/2mv^2 - 1/2mvo^2
What is the equation for kinetic energy?
U = mgh
What is the equation for potential energy?
Energy can neither be destroyed or created, it is transferred
What does the law of conservation of energy say?
Power
one useful application of energy is to determine RATE at which we store or use energy
P = W/(change in time)
What is the equation for power?
you find the the centripetal acceleration (or just acceleration), and divide that by gravity (9.81 m/s^2)
How do you find "g's" of acceleration?
you write your answer as example: ac = 3.81 g
How do you write your answer when solving for "g's" of acceleration?
You use the conservation of energy theory at the first point on the roller coaster to set equal to whatever point you are solving for
How do you do roller coaster problems?
draw a free body diagram
What is the best first thing to do when you have a problem with forces being applied?
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