Work
True or False. The definition of work is: A force is applied to an object and the object moves in the opposite direction of the force.
False. To be work, the force and motion must be in the same direction.
The energy of moving electrons in wires is called ____________ energy.
electrical
Energy cannot be created or destroyed
The unit work is measured in is...
Joules
If a person uses 90N of force to push a box 2m in the direction of their push, how much work was done? (Unit must be correct)
180J
Potential Energy PLUS Kinetic Energy is equal to this.
Mechanical energy
The movement of atoms and molecules. This is called ______ energy.
thermal
Imagine a diver jumping off of a diving board. At what point does the diver have the most potential energy?
While standing on the diving board.
The unit energy is measured in is...
How much work is done if someone hold a 4kg book over their head (2m high) for 3 hours?
No work, because there is no motion.
Stored energy in food, gasoline, and other substances is called ______________ energy. Is it kinetic or potential?
chemical; potential
Ignoring air resistance, if a rock is falling from a 100m cliff, at what height in the fall is the gravitational potential energy equal to the kinetic energy?
At 50m.
The formula for weight is...
mass x acceleration due to gravity
Is work a vector or a scalar?
Scalar
Energy that comes from an atom's nucleus is called ________ energy.
nuclear
When a golf ball is released and bounces on the ground, why does it not then return to the same height it was dropped from?
Energy is lost to sound and heat
Why can't a perpetual motion machine work forever?
Eventually, all of the energy will be converted to thermal energy through friction and the machine will stop.
A 30kg child is asking his mother to pick him up. She will have to lift him 1m in order to do so. How much work will she have to do in order to pick up her child? (unit must be correct)
30kg x 9.8 m/s/s = 294N x 1m = 294J (estimated 300J is also OK)
This is the point in a fall when an object has the most kinetic energy.
This type of energy occurs when an object vibrates, and this caused the air to vibrate.
sound
If a diver weighs 500N and is standing on a 3m diving board, what will the diver's total mechanical energy be right before they hit the water? (Ignore air resistance) (The unit must be correct)
GPE = 500N x 3m = 1500J (total mechanical energy will be equal to the gravitational potential energy)
In what year did Isaac Newton publish his 3 laws of motion? (Plus or minus 5 years)
1687! (if you answered in the range of 1682-1692, it counts)