force
distance
in science, work is the product of ------- and --------
work=force x distance
work equation
moving
for work to happen, the object must be -------- in that instant
force
motion
the amount of work done on an object depends on the direction of the ------- and the direction of the ---------
by
work is done ---- objects whose force applied goes in the direction of motion (who/what causes motion)
on
work is done ------ objects whose force applied goes in the opposite direction of motion (who/what is being moved)
box
work done on = --------
human
work done by = -------
joule (j)
the ------ is the unit for work
newton
meter
1 joule is equal to the force of 1 ------- applied on one ----- in the direction of force
kg x m/s2
remember: 1N =----------
kg x m2/s2
so units of a joule are 1 --------
rate
power is the ------ at which work is done
faster
doing work at a ----- rate gives you more power
power= work/time
power equation
watts (w)
units of power are ------
j/s
one watt= -------
horsepower
the term --------- was first defined by scottish scientist james watt (1736-1819)
746 (1hp=746 watts
after many experiments, james watt calculated that the average power that one horse put out was equal to ------ watts
there must be a force exerted on the object and it must move in the direction of the force
describe the conditions that must exist for a force to do work on an object
A power level of 1 hp is approximately equivalent to 746 watts (W)
compare the units of watts and horsepower as they relate to power
machine
a -------- is a device that changes a force
size
direction
distance
machines make work easier to do by changing the ------ or force needed, the -------- of the force, or the -------- over which the force acts
force
distance
remember that work = ------- x -------
decrease
some machines ------- the applied force, but increase the distance over which the force is exerted
force
the trade-off is that the longer the oars get, the more ---- the person has to apply in order to move the oars quickly
direction
other machines can change the ------- of the applied force
input
the force you exert on a machine is called the ------- force
distance
the distance the input force acts through is called the input --------
work
the work done by the input force through some input distance is the ------- input
output
the force that is exerted by the machine is called the ----- force
distance
the distance the output force is exerted through is the output -------
output
the output force moving through the output distance is the work -------
sometimes
in reality, this is not correct, and the work output is ------ less than the work input
any device that makes work easier by changing a force. Machines may increase the strength of the force, increase the distance over which the force is applied, or change the direction in which the force is applied
describe what a machine is and how it makes work easier to do
Work input is work done on a machine to get the desired output. Work output is the amount of desired work that is done by a machine. For an ideal machine, the work output is equal to the work input
relate the work input to a machine to the work output of a machine
advantage
the mechanical -------- of a machine is the number of times that the machine increases the input force
higher
the mechanical advantage of part A is ------ than part B or your hand
divided
the actual mechanical advantage of a machine is equal to the output force ------- by the input force
actual mechanical advantage = output force/input force
actual mechanical advantage equation
friction
the actual mechanical advantage takes into account of ------- acting on the object
ideal
the ------- mechanical advantage is the mechanical advantage in the absence of friction
higher
without friction, the ideal mechanical advantage of a machine would be much ------- than the actual mechanical advantage
distances
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= input distance/output distance
ideal mechanical advantage equation
one
in most cases, the mechanical advantage will be greater than ------ because the input distance will be larger than the output distance
efficiency
the ------- of a machine is the % of the work input that becomes work output
efficiency= work output/work input x 100%
efficiency equation
100%
because there is always some friction, the efficiency of any machine is always less than --------
The actual mechanical advantage of a machine reflects the increase or decrease in force achieved by the machine. It takes into account the force needed to overcome friction. The ideal mechanical advantage of a machine reflects the increase or decrease in force there would be without friction
compare a machine’s actual mechanical advantage to its ideal mechanical advantage
the output of a machine is always less than the input
explain why the efficiency of a machine is always less than 100%
simple
a ------- machine consists of one place to have an input force and one place of an output force
lever
a ------ is an object, or bar, that is free to move around a fixed point
fulcrum
the fixed point that the bar rotates around is called the ---
distance
the input arm of a lever is the ------ between the input force and the fulcrum
fulcrum
the output arm is the distance between the output force and the ------
first
in a ----- class lever, the fulcrum is between the input arm and the output arm
force
in a second class lever, the output ------- is located between the input force and the fulcrum
fulcrum
in a third class lever, the input force is located between the ------- and the output force
wheel
axle
a -------- and ------- is a simple machine that consists of 2 disks each with a different radius
input
output
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
inclined plane
an -------- --------- is a slanted surface along which a force moves an object to a different elevation
wedge
a -------- is a v-shaped object whose sides are 2 inclined planes sloped towards each other
higher
the thinner the edge of the wedge, the ------- the mechanical advantage
screw
a ------- is an inclined plane wrapped around a cylinder
higher
for 2 screws with the same length, the one whose threads are closer together have a ----- mechanical advantage
pulley
a -------- is another simple machine that consists of a rope that fits into a groove in a wheel
fixed
a ------- pulley is a whee; attached in a fixed location
constant
the direction of the force applied is changed in a fixed pulley, but the size of the force is --------
movable
a ------- pulley is attached to the object being moved rather than to a fixed location
direction
size
movable pulleys change both the ------- and the ------ of the input force
pulley system
a combination of fixed an moving pulleys is a --------- ----------
increases
as the number of pulleys --------, so does the mechanical advantage
compound
a ------- machine is a combination of 2 or more simple machines that operate together
The inclined plane: Examples are ramps, staircases, hilly roads, etc. The wedge: Examples are knife, axe, plough, knife, etc. Screw: Examples are A screw bolt. The wheel and axle: Examples are the steering wheel of a car, bicycle pedal, etc. lever example: shovel; pulley example: flagpole
name, describe, and give an example of each of the 6 types of simple machines
To calculate the ideal mechanical advantage of the wheel and axle, divide the radius (or diameter) where the input force is exerted by the radius (or diameter) where the output force is exerted. To calculate the ideal mechanical advantage of any lever, divide the input arm by the output arm.
describe how to determine the ideal mechanical advantage of each type of simple machine
A compound machine is a machine consisting of two or more simple machines. Some examples of compound machines are clippers, a manual pencil sharpener, a crane, and a bulldozer.
define and identify compound machines