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Energy
Conservation of Energy
Power
Problems
Misc.
100
What is stored energy associated with an object due to the position of the object?
Potential Energy
100
What are two examples of a conserved quantity?
mass and energy
100
What is the definition of power?
the rate at which work is done
100
A 1500 kg car accelerates uniformly from rest to 10 m/s in 3.00 s. What is the power delivered by the engine in this time interval?
25000W
100
Which of the following have a combination of mechanical and nonmechanical energy? a. glowing embers in a campfire b. a strong wind c. a swinging pendulum d. a person sitting on a mattress e. a rocket being launched into space
e. a rocket being launched into space
200
What is the unit for "k"?
N/m
200
What is mechanical energy?
the sum of kinetic energy and all forms of potential energy
200
What is the unit for power?
Watt or J/s
200
A spring with a force constant of 5.2 N/m has a relaxed length of 2.45 m. When a mass is attached to the end of the spring and allowed to come to rest, the vertical length of the spring is 3.57 m. What is the elastic potential energy stored in the spring?
3.3 J
200
Find the before and after energy for the following situation: A kicker punts a football starting .75 m off the ground with an initial speed of 3.3 m/s. How high in the air will the football go?
PE + KE = PE + 0
300
What is the type of energy that depends on the distance stretched or compressed?
Potential Elastic Energy
300
What is conservation of energy?
Energy cannot be created or destroyed, just transformed from one type to another.
300
What is 10000 W in horsepower?
13.4 hp
300
A spoon is raised 21.0 cm above a table. If the spoon and its contents have a mass of 30.0 g, what is the gravitational potential energy associated with the spoon at that height relative to the surface of the table?
.0618 J
300
What is the BIG clue that you have a problem involving elastic potential energy?
a spring or elastic material
400
What is the type of energy that is due to motion of an object?
Kinetic Energy
400
What is mechanical energy converted into in the presence of friction?
Heat (nonmechanical energy)
400
What do the different power ratings of machines mean?
they do the same amount of work in different time intervals
400
A pendulum bob is released from some initial height such that the speed of the bob at the bottom of the swing is 1.9 m/s. What is the initial height of the bob?
.18 m
400
What happens to energy in the presence of friction?
It can no longer be conserved. Energy is transferred from one form to another (heat) which we can't calculate.
500
What are the equations for both types of potential energy?
PEg = mgh PEel = .5kx^2
500
What is the most expanded equation for conservation of energy?
mgh + .5mv^2 = mgh + .5mv^2
500
What are the two equations for power?
P = W/t P = Fv
500
An Olympic runner leaps over a hurdle. If the runner's initial vertical speed is 2.2 m/s, how much will the runner's center of mass be raised during the jump?
.25 m
500
What is the height of a crate at the top of a 13 m ramp at 32 degrees?
6.9 m