chapter 12 Flashcards
a quantity that measures the rate at which work is done or energy is transformed
power
a machine made up of more than one simple machine
compound machine
the most basic machines
simple machines
the transfer of energy to a body by the application of a force that causes the body to move in the direction of the force
Work
modified levers
pulley
a lever or pulley connected to a shaft
wheel and axle
have a fulcrum located between the points of application of the input and output forces.
first-class lever
the fulcrum is at one end of the arm and the input force is applied to the other end.
second-class lever
multiply distance rather than force. As a result, they have a mechanical advantage of less than 1.
third-class lever
the sum of potential and kinetic energy in a system
mechanical energy
change from mechanical energy due to friction or air resistance
nonmechanical energy
energy at rest or stored energy, is at its highest at the peak of the arch
potential energy
what turns mechanical energy to nonmechanical energy
friction, air resistance, or other means
exchanges energy with the space that surrounds them
open system
flow of energy is slow enough to be ignored
closed system
what is the source of the sun’s energy
nuclear fusion reactors in the core
efficiency = useful work output / work input
efficiency equation
what are the two levels of simple machines
lever and inclined plane family
what is the mechanical advantage of a pulley
1
what is a wedge
a modified inclined plane
law of conservation of energy states
energy cannot be created nor destroyed
unit of measurement for work
joules
unit of measurement for power
watts
energy stored in the gravitational field which exists between any two or more objects
PE = mgh
Gravitational potential energy
multiple pulleys together
block and tackle
work equation
W = F x d work = force x distance
power equation
P = W / t power = work / time
mechanical advantage equation
mech. adv. = output force / input force
gravitational potential energy equation
PE = mgh
grav. PE = mass x free-fall acceleration x height
kinetic energy equation
KE = 1 / 2mv ̂2 KE = 1 /2 x mass x speed squared
efficiency equation
efficiency = useful work output / work input
