Energy and Work
This is done when a force causes an object to move a given distance.
Work
What is the formula for potential energy
Mass x Gravity x Height or Weight x Height
Kinetic energy is the energy of
Motion
A ramp is an example of this type of simple machine.
Inclined plane
What is the unit for power?
Watt
What is the formula for work?
Force x Distance
What is the formula for weight?
mass x force due to gravity(~10 m/s2)
What is the kinetic energy of a car that has a mass of 800Kg that is stopped at a stoplight?
Zero
This type of machine is used to split things
Wedge
This type of machine combines 2 or more simple machines.
Compound Machine
This type of energy is the energy of an object due to the object's motion
Kinetic Energy
If an object was on a 5m hill on Earth and an identical object was on a 5m hill on the moon which would have more potential energy?
The one on Earth
What is the formula for kinetic energy?
KE = 1/2 mv2
This type of machine includes wheels and axles with a groove around the outside
Pulley
A machine is a device that can multiply _______.
How much work is done to lift an object that weighs 500N to a height of 5 meters?
2500 Joules (500N x 5m)
What is the potential energy of a 100N car that is on a hill 2 meters high?
200 Joules (100N x 2m)
A ball has kinetic energy when it rolls. If it rolls twice as fast how much more does its kinetic energy change?
4 times increase in KE.
This type of simple machine is an inclined plane wound around a central cylinder.
Screw
If you have to apply 50N of force on a lever to lift an object that weights 100 N, what is the actual mechanical advantage of the crowbar
2 (100N / 50N)
This is the force exerted on a machine
Input Force
When a soccer ball is kicked, this is when it has the greatest potential energy.
When it is at its highest point
A 50Kg cart is travelling at 10 m/s. What is its kinetic energy?
2,500 Joules (1/2 x 50g x 102)
Give one example each for a 1st class, 2nd class and 3rd class lever.
Answers vary
If you exert a force of 500N to walk 5m up a flight of stairs in 10s, how much power do you use?
250 Watts (500 x 5) / 10