Science- Work and Simple Machines
efficiency
the ratio of output work to input work
Power is determined by dividing the work done by the amount of ____ needed to do the work.
time
in the power equation, _____ is in seconds.
time
to move from one place to another
transfers
in the power equation, power is in ________.
watts
a sloped surface that moves is called a _______.
wedge
the work done to lift any object is equal to the ______ of the object multiplied by the distance the object is lifted.
weight
a _______ is an axle attached to the center of a wheel and both rotate together.
wheel and axle
______ is done because the input force causes movement.
work
______ is the transfer of energy that to an object by a force that makes an object move in the direction of the force.
work
in the power equation, _______ done is in joules.
work
the output work done by a machine never exceeds the input ______ of the machine.
work
transfer of energy to an object by a force that makes an object move in the direction of the force
work
a machine can make work easier by...
-changing the size of the force -change the direction of the force -change the distance over which it acts
a machine can make work easier in ________ different ways
3
When the force on an object is at an _____ to the direction of motion of the object, you multiply only the part of the force that is in the _____ of motion times the total distance to determine the amount of work done.
angle direction
With a first class lever the fulcrum is _________ the input force and the output force
between
a machine ____ the way in which work is done
changes
two or more simple machines that operate together form a ______ machine
compound
The weight of any object is due to the downward force of ____ on the object.
gravity
a mechanical advantage _____ than 1 means the output force is greater than the input force
greater
a second-class lever makes the output force ______ than the input force.
greater
A _______ is a flat, sloped surface.
inclined plane
it takes less force to move an object upward along an ___________ than it does to life the object straight up.
inclined plane
screw
inclined plane wrapped around a cylinder
With a third class lever the _______ force is between the ______ force and the fulcrum
input output
in a second class lever the _____ arm is always longer than the ______ arm.
input output
in a third class lever, the _______ arm is always shorter than the _____ arm.
input output
machines convert _____ work to ________ work
input output
the machine changes the _____ force to an ______ force
input output
a machine can change a ____ force into a large _____ force.
input output
the distance from the fulcrum to the input force is the ________; the distance from the fulcrum to the output force is the __________.
input arm output arm
a second-class lever has the output force between the _______ and the _______.
input force fulcrum
when a hammer removes a nail, the _____ comes from pulling on the hammer's handle, the hammer changes this to a ____ that pulls the nail from the board
input force output force
when the teeth of two or more gears ______, the turning of one gear makes the other turn.
interlock
a newton-meter is also called a ______, which is the unit of work
joule (J)
Because doing work on an object requires that the object move, doing work on the object increases its ____ energy.
kinetic
a sloped surface that moves is called a ______.
ledge
the ideal mechanical advantage of an inclined plane equals its _______divided by its _______.
length height
the ideal mechanical advantage of an inclined plane is the _________ of the inclined plane divided by its _______.
length height
a mechanical advantage _____ than 1 means the output force is less than the input force
less
a _______ is a simple machine made of a bar that pivots or rotates about a fixed point.
lever
a ______ is any device that makes doing something easier.
machine
lever
made up of a bar that turns on a fixed point or a fulcrum
wheel and axle
made up of a shaft, or axle, attached to the center of a wheel such that both rotate together
the ideal _________ of a lever equals the length of the input arm divided by the length of the output arm.
mechanical advantage
the distance must be in ______
meters (m)
a ______ pulley decreases the force but increases the distance over which the force acts.
movable
when you use a machine, the input force makes part of the machine ____
move
a weightlifter does work when exerting a force that makes weights _____, but does no work to hold weights in place because the weights are not _______
move moving
the efficiency of a compound machine is determined by ______ the efficiency of each component machine together.
multiplying
in the human body, ______ provide force to the levers.
muscles
the force must be in _______
newtons (N)
with a second-class lever, the _______ force is between the _________ force and the fulcrum
output input
fulcrum
point about which a lever pivots, or rotates
lifting an object increases the object's gravitational ____ energy
potential
______ is the rate at which work is done.
power
rate at which work is done
power
a _______ is a simple machine that is a grooved wheel with a rope or cable wrapped around it.
pulley
for a wheel and axle the length of the input arm is the _____ of the wheel the length of the output arm is the ____ of the axle
radius radius
what is an example of a third class lever?
rake
another word for an inclined plane is a ________
ramp
moving a sofa is easier using a ______.
ramp
effiiency
ratio of output force to input force
mechanical advantage
ratio of output force to input force
a _________ is an inclined plane wrapped around a cylinder.
screw
The foot is a(n) ___ -class lever, and the arm is a(n) ____ -class lever.
second third
the ideal mechanical advantage of a pulley is equal to the number of ______ of rope pulling up on the object.
sections
With a rake, your hands move through a(n) ____ distance, but the other end of the rake moves through a(n) ___ distance.
short greater
the output force acts over a ______ distance than the input force does
shorter
a ________ is a machine that does work using only one movement.
simple machine
these machines do work in a ____ motion
singular
the speed and force of gears is affected by the _______ of the gears.
size
Because output work is always less than input work...
the efficiency of a machine is always less than 100%
wedge
a sloped surface that moves
Because of _______, no ramp operates at its ideal mechanical advantage.
friction
the point that a lever pivots on is called a _____.
fulcrum
a _______ is a wheel and axle that has teeth around the wheel.
gear
the work equation uses the distance that the _______ acts on the object, not necessarily the total ______ that the object moves.
force distance
a finger tab is an example of what class of lever?
a first-class lever
inclined plane
a flat, sloped surface
pulley
a grooved wheel with a rope or cable wrapped around it
simple machine
a machine that does work using only one movement
A wheel barrow is an example of what class of lever?
a second-class level
Although a machine makes doing work easier, it does not _____ the amount of work required
decrease
as the output force exerted by any machine _____, the output distance ______
decreases increases
The work done on an object depends on the ______of the force applied and the direction of motion.
direction
a fixed pulley only changes the ______ of the force.
direction
doing work on an object increases transfers _____ to the object.
energy
a mechanical advantage equal to 1 means the input force and the output force are _____, but the direction of the input force ______.
equal changes
to lift an object, you must pull upward on the object with a force ______ to the object's.
equal or greater
the mechanical advantage of a ______ class lever can vary, depending on the location of the fulcrum
first
the neck is a _____ class lever, with the neck muscles providing the ______ force.
first input
a _______ pulley only changes the direction of the force.
fixed pulley
the longer or less-sloped an inclined plane is, the less ______ is needed to move an object along its surface.
force
to use a machine, you must apply a ______ to it.
force
when the force on an object and the motion of the object are in the same direction, you multiply the total ______ times the total distance to determine the amount of work done.
force
you must know two things to calculate work---- ______ and _________
force distance