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16 terms

Work & Machines

Chapter 4
STUDY
PLAY
Ideal machine
100% efficiency
Fulcrum
fixed point that a lever rotates around
Compound Machines
combination of simple machines
Elbow
acts as the fulcrum when bending your arm
Wheel & Axle
door knob
Wedge
chisel
Pulley
block & tackle
Inclined Plane
sliding board
Lever
broom
Screw
light bulb
3 Ways Machines Make Work Easier
1. changing the amount of force you exert. 2. the distance over which you exert force. 3. the direction in which you exert force.
Work
1. force must be applied to object
2. object must move same direction as force
100 % Efficiency?
Not possible - some work is wasted due to friction
Great Pyramids
simple machines: wedges & inclined planes
W = Force x Distance
50 N box pushed 10 meters
W = 50 x 10; W = 500 N/M
P = W/T
takes 10 sec. to move the box
P = 500/10; P = 50 W