chapter 3 Flashcards
Work
the transfer of energy that occurs when a force is applied over a distance
Work Equation
work (in joules) = force (in newtons) x distance (in meters)
W = Fd
Power
rate at which work is done
Power Equation
power (in watts) = work (in joules)/time (in seconds)
P = w/t
Mechanical advantage
the ratio of a machine’s output force produced to the input force applied
Mechanical advantage
output force (in newtons)/ input force (in newtons)
MA = F out / F in
Efficiency
a machine is the ratio of the output work to the input work
Efficiency (in %)
output work (in joules)/ input work (in joules) x 100%
Efficiency = W out/ W in x 100%
Simple machines
do work using only one movement
Lever
a simple machine made up of a bar that pivots, or rotates, about a fixed point
Fulcrum
The point about which a lever pivots
Wheels and axle
is an axle attached to the center of a wheel and both rotate together
Ideal mechanical advantage
radius of wheel (in meters)/ radius of axle (in meters)
IMA = R wheel/ R axle
Inclined plane
a flat, sloped surface, or a ramp
Ideal mechanical advantage
Inclined Plane equation
length of inclined plane (in meters)/ height of inclined plane (in meters)
IMA = l/h
Wedge
A sloped surface that moves
Screw
an inclined plane wrapped around a cylinder
Pulley
a simple machine that is a grooved wheel with a rope or a cable wrapped around it
what must you know to calculate work
force and distance
what happens when work is done on an object
the energy of the object increases
What is the rate at which work is done
power
what three ways can a machine make work easier in three ways
changing the size of a force, changing the distance of the force acts, or changing the direction of a force
what is the mechanical advantage of a machine
the ratio of the output force to the input force
Because the friction, the output work done by a machine is always_______than the input work of the machine
less
