science

what is work?

the transfer of energy to an object by a force that makes an object move in the direction of the force.

what happens to an object when a force does not move?

it results in making the object do no work

what is work-energy theorem?

whenever work is done, energy changes

what is power?

the speed at which work is done

what happens when you lift an object?

the work done on the object increases its energy

does speed change the amount of work done?

no, how quickly you lift an object does not impact the amount of work you did

what do machines do?

change the amount of force you exert or the distance over which you exert the force, thus making the work easier

do machines decrease the amount of work done?

no, but they can make it easier by changing the way in which work is done

what do machines do to input force?

changes it into an output force

are forces vectors?

yes, forces are vectors

what does an output force do to an object?

it makes the object move

name three ways machines make work easier

-make your force stronger
-make your force last a longer distance while using less force
-change the direction of your force

how are work and power related?

power is the rate at which work is done.

how is work done?

applying a force on an object so that it moves in that direction

how does doing work on an object change it's energy?

transfers energy to an object which results in giving the object kinetic and

explain what happens when you do more work on an object.

the more work done on an object the more power will be used to do that work.

what happens when it takes more time to do work.

less power will be used to do that work

can machines be 100% efficient?

they can not be 100% efficient because friction is always present.

what is mechanical advantage? (MA)

the measure of how much a machine increases your input force, it also tells us which of the 3 ways a machine is making work easier.

what is a tradeoff in a machine?

it can increase the strength of your input force OR increase the distance over which it acts, BUT IT CANNOT DO BOTH AT THE SAME TIME.

name 6 kinds of simple machines

-levers
-wheel&axel
-pulley
-inclined plane/ramp
-wedge
-screw

what is input force?

the force you exert on a machine

what does a 1st class lever have in the middle?

the fulcrum

what is the fulcrum?

the pivot point of the lever

what does a 2nd class lever have in the middle?

the load

what is known as the effort?

the input force you use to operate the lever

what is known as the load?

the output force that the lever lifts/lowers

what does a 3rd class lever have in the middle?

the effort

frogs lay eggs

1 2 3
F.L.E.
u o f
l a f
c d f
r. o
u r
m t

what is the mechanical advantage of a first class lever?

could be greater than 1, equal to 1, or less than 1

what is the mechanical advantage of a second class lever?

always greater than 1 and will always increase the amount of your input force

what is the mechanical advantage of a third class lever?

always less than 1 and always increase the distance the input force acts

what is a wheel and axel?

an axel attached to the center of a wheel. both rotate together. and they always increase the amount of our input force.

what is an inclined plane?

a flat, sloped surface that makes lifting loads easier. it also increases your input force but makes us apply the force a longer distance

what is a wedge?

helps us cut or separate two objects. it is a slopped surface that moves.

what is a screw?

an inclined plane that is wrapped around a cylinder

what is a pulley?

a simple machine made of a grooved wheel with a rope or cable wrapped around it. it helps us lift loads and change direction of the force applied.

what is a compound machine?

when two or more simple machines are used together. compound machines are less efficient than simple machines at doing work.