Flash Card #10
What is work?
when the object moves in the same direction in which the force is exerted.
What is the formula for work?
Work=ForcexDistance
What is power?
The amount of work done on an object in a unit of time.
What is the formula for power?
Power=Work over Time
What is a machine?
is a device that allows you to do
work (Wi) easier or more effectively.
What are the three factors that make machines work easier?
1] the amount of force you exert (input force, Fi)
2] the distance over which you exert your force
(input distance, Di)
3] the direction in which you exert your force
(input direction)
What is the formula for machines?
W = F x D
What are levers?
rigid bar that pivots/rotates on a fixed
point.
What is a fulcrum?
fixed point that a lever pivots
around.
How do machines work?
Fi x Di = Fo x Do where i= input, o = output
Fi = Fo x Do
Di = Fo x Do
Di
Fi
Fo = Fi x Di
Do = Fi x Di
Do
Fo
What is mechanical advantage?
the number of
times a machine increases the input force (Fi).
MA = Fo
Fi
What is efficiency?
compares output work to input work.
An ideal machine’s efficiency = 100%. A real
machines efficiency is less than 100% because
some output work (Wo) is lost due to friction (heat
loss).
Efficiency = W0 x 100 = ______ %
Wi
What is a wheel and Axle?
two circular/cylindrical objects
that are connected together and rotate around
a common axis, where:
Wheel: larger radius object
Axle: smaller radius object
What is a pulley?
a grooved wheel with a rope (cable)
wrapped around it.
What are the types of pulleys?
Fixed Pulley, Movable Pulley and Block & Tackle
