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