work
transfer of energy to an object by force that makes an object move in the direction of the force being applied to the object.
power
the rate at which work is done
mechanical advantage
the ratio of a machine's output force produced to the input force applied.
efficiency
the ratio of the output work to the input work.
simple machine
machines that do work using only one movement
lever
simple machine made up of a bar that pivots, or rotates, about a fixed point.
fulcrum
the point about which a lever pivots
wheel and axle
simple machine that consists of an axle attached to the center of a larger wheel, so that the shaft and wheel rotate together
inclined plane
a flat, sloped, simple machine
wedge
sloped surface that moves
screw
inclined plane wrapped around a cylinder
pulley
simple machine that is a grooved wheel with a rope or cable wrapped around it.
What is the equation for work?
force x distance
What is the SI unit for work?
Joules (J)
What factors affect work?
force at an angle and lifting objects
Which transfers both kinetic and potential energy to an object?
Lifting the object
What is the equation for power?
work
time
What is the SI unit for power?
Watts (W)
What are the three things a machine can do for you?
change the size of a force
change the distance the force acts
change the direction of a force
What is a machine that can change the size of a force and how?
A crowbar by changing an input force into a larger output force. Even though the output force is greater than the input force, it acts over a shorter distance.
What is a machine that can change the distance a force acts and how?
A rake by being longer. The output force is smaller than output distance.
What is the mechanical advantage equation?
output force
input force
What is the efficiency equation?
output work
input work X100
What is the SI unit for efficiency?
%
What are the six types of simple machines?
Levers
Wheel and Axle
Inclined Plane
Screw
Wedge
Pulley
What are the three types of levers?
First-class lever
Second-class lever
Third-class lever
Where is the fulcrum in a first-class lever?
Between the output and input forces
What is an example of a first-class lever?
A pop can tab or a hammer
Where is the fulcrum in a second-class lever?
the output force is between the input force and the fulcrum.
What is an example of a second-class lever?
A wheelbarrow or a nutcracker
Where is the fulcrum located in a third-class lever?
The input force is between the output force and the fulcrum.
What is an example of a third-class lever?
Tweezers or a rake
What is the equation for the mechanical advantage of a lever?
length of input arm
length of output arm
What are some examples of a wheel and axle?
a screwdriver and a wheel
What is the equation for the ideal mechanical advantage of a wheel and axle?
radius of wheel
radius of axle
What is the mechanical advantage of an inclined plane?
length of inclined plane
height of inclined plane
What are some examples of wedges?
your front teeth, a doorstop, and the top of an ax
What are some examples of screws?
Top of a jar and a wooden screw
What are the three types of pulleys?
Fixed pulleys, movable pulleys, and pulley systems.
How do you find the efficiency of a compound machine?
multiply all the efficiencies together.
What are always equal?
Input work and output work.