Energy Transformations
Define potential OR kinetic energy
kinetic --> particles in motion
potential --> energy stored or space between particles
Give me an example of someone doing work.
Any answer where force is applied and the object moves
What is a machine?
Any device that makes doing something easier
What is a simple machine?
machines that do work using only movement
A student uses a pulley but says the load feels heavy. What likely reduced efficiency?
Friction in the rope
as a ball goes up, kinetic energy .....
decreases
Define work
Transfer of energy that occurs when a force makes an object move
What is the input force?
The force you apply to a machine
Where is the input force located on a third class lever?
in the middle!
second class (output is in the middle)
first class (fulcrum is in the middle)
A lever pivots around a fixed point called the:
Fulcrum
All forms of energy can be transformed into...
thermal energy
Define power
The rate at which work is done
or
How fast energy transferred to an object
Name one way a machine makes work easier to do.
1. Changing the size of the force
2. Changing the distance the force acts
3. Changing the direction of the force
In a wheel and axle in what direction do the input and output forces rotate?
They rotate together
Khun pushes a box 5 m across the floor using a constant force of 20 N. How much work was done?
100 J
When energy transfers forms what else is released?
waste energy
What is the equation for work or power?
work = force x distance
power = work/time
What is mechanical advantage?
The ratio of a machine’s output force to the applied input force
What is the mechanical advantage for a moveable pulley?
IMA = 2
two pieces of rope support the item on a moveable pulley
The ideal mechanical advantage of a wheel and axle is:
Radius of wheel ÷ radius of axle
What does the law of conservation of energy say?
energy cannot be created or destroyed
What are all the units used in the work equation?
1. Joules (work)
2. Force (newtons)
3. Distance (meters)
Why can efficiency never be equal to 100%?
FRICTION!!
Name all 6 simple machines
1. lever
2. wheel and axel
3. inclined plane
4. wedge
5. screw
6. pulley
A screw is
An inclined plane wrapped around a cylinder