chapter 14: work, power, and machines

in science, work is the product of ------- and --------

work equation

for work to happen, the object must be -------- in that instant

the amount of work done on an object depends on the direction of the ------- and the direction of the ---------

work is done ---- objects whose force applied goes in the direction of motion (who/what causes motion)

work is done ------ objects whose force applied goes in the opposite direction of motion (who/what is being moved)

work done on = --------

work done by = -------

the ------ is the unit for work

1 joule is equal to the force of 1 ------- applied on one ----- in the direction of force

remember: 1N =----------

so units of a joule are 1 --------

power is the ------ at which work is done

doing work at a ----- rate gives you more power

power equation

units of power are ------

one watt= -------

the term --------- was first defined by scottish scientist james watt (1736-1819)

after many experiments, james watt calculated that the average power that one horse put out was equal to ------ watts

describe the conditions that must exist for a force to do work on an object

compare the units of watts and horsepower as they relate to power

a -------- is a device that changes a force

machines make work easier to do by changing the ------ or force needed, the -------- of the force, or the -------- over which the force acts

remember that work = ------- x -------

some machines ------- the applied force, but increase the distance over which the force is exerted

the trade-off is that the longer the oars get, the more ---- the person has to apply in order to move the oars quickly

other machines can change the ------- of the applied force

the force you exert on a machine is called the ------- force

the distance the input force acts through is called the input --------

the work done by the input force through some input distance is the ------- input

the force that is exerted by the machine is called the ----- force

the distance the output force is exerted through is the output -------

the output force moving through the output distance is the work -------

in reality, this is not correct, and the work output is ------ less than the work input

describe what a machine is and how it makes work easier to do

relate the work input to a machine to the work output of a machine

the mechanical -------- of a machine is the number of times that the machine increases the input force

the mechanical advantage of part A is ------ than part B or your hand

the actual mechanical advantage of a machine is equal to the output force ------- by the input force

actual mechanical advantage equation

the actual mechanical advantage takes into account of ------- acting on the object

the ------- mechanical advantage is the mechanical advantage in the absence of friction

without friction, the ideal mechanical advantage of a machine would be much ------- than the actual mechanical advantage

calculating ideal mechanical advantage is easier than actual mechanical advantage because you can focus solely on the locations of the forces and ----- in which they act

ideal mechanical advantage equation

in most cases, the mechanical advantage will be greater than ------ because the input distance will be larger than the output distance

the ------- of a machine is the % of the work input that becomes work output

efficiency equation

because there is always some friction, the efficiency of any machine is always less than --------

compare a machine’s actual mechanical advantage to its ideal mechanical advantage

explain why the efficiency of a machine is always less than 100%

a ------- machine consists of one place to have an input force and one place of an output force

a ------ is an object, or bar, that is free to move around a fixed point

the fixed point that the bar rotates around is called the ---

the input arm of a lever is the ------ between the input force and the fulcrum

the output arm is the distance between the output force and the ------

in a ----- class lever, the fulcrum is between the input arm and the output arm

in a second class lever, the output ------- is located between the input force and the fulcrum

in a third class lever, the input force is located between the ------- and the output force

a -------- and ------- is a simple machine that consists of 2 disks each with a different radius

to calculate the ideal mechanical advantage of the wheel and axle, divide the radius where the ------- force is exerted by the radius where the ------ force is exerted

an -------- --------- is a slanted surface along which a force moves an object to a different elevation

a -------- is a v-shaped object whose sides are 2 inclined planes sloped towards each other

the thinner the edge of the wedge, the ------- the mechanical advantage

a ------- is an inclined plane wrapped around a cylinder

for 2 screws with the same length, the one whose threads are closer together have a ----- mechanical advantage

a -------- is another simple machine that consists of a rope that fits into a groove in a wheel

a ------- pulley is a whee; attached in a fixed location

the direction of the force applied is changed in a fixed pulley, but the size of the force is --------

a ------- pulley is attached to the object being moved rather than to a fixed location

movable pulleys change both the ------- and the ------ of the input force

a combination of fixed an moving pulleys is a --------- ----------

as the number of pulleys --------, so does the mechanical advantage

a ------- machine is a combination of 2 or more simple machines that operate together

name, describe, and give an example of each of the 6 types of simple machines

describe how to determine the ideal mechanical advantage of each type of simple machine

define and identify compound machines