Chapter 4 Section 1 Flashcards
Machines make doing work easier or faster by changing the _____ needed to do the work
force
Work is a _____ applied through a _____
or
the _____ transferred when a _____ makes an object _____
force
distance
energy
force
move
what is the formula for work
W = F x d
What is the unit used to measure work?
joules ( J )
For you or a force to do work, 3 conditions must be met:
- you have to be physically touching the object
- the object must move
- the movement of the object must be in direction of the force
What always occurs when work is done?
a transfer of energy
When you do work on an object, you increase the objects _______ because _______
energy
you gave the object your own energy (Transfer)
When are you doing work on an object?
when you are physically touching the object applying force
what happens if the object keeps moving after you apply force
you are no longer doing work on the object because you are no longer touching the object
When the force and motion of the object are ______ the maximum amount of work is being done
parallel
When the force and motion of the object are ______ then no work is being done
perpendicular
when the force and motion of the object are ______ less than maximum (partial) work is being done
at an angle
a machine is a device that _____ or _____
changes the force
increases the motion from work
A simple machine is a machine that does _____ with only _____
work
one movement of the machine
What are the six simple machines
lever
pulley
wheel and axel
inclined plane
wedge
screw
What are the modified levers and inclined planes
levers: pulley, wheel and axel
inclined planes: wedge, screw
A compound machine is a combination of _____
two or more simple machine
Efficiency is the ratio of _____ to _____
output work to input work
No machine can increase both _____ and _____ at the same time
force
speed
You always put more _____ into a machine than you get out of that machine
work
No machine is 100% efficient because of _____
friction
what is the formula for efficiency
EFF = Wout/Win x 100
An _____ is a theoretical machine in which the amount of work put into the machine (Win) is equal to the amount of work you get out of the machine (Wout)
ideal machine
Why do ideal machines not exist
friction
Machines _____ the speed of getting work done
increase
Machines multiply/increase _____
force
Machines change the _____ of the force
direction
Do machines always multiply/increase force
no
We can describe the effectiveness of a machine by increasing _____ by its mechanical advantage
force
Input force is the force that…
a person or device such as a motor applies to the machine
Output force is the force that…
the machine applies to another object
What is the formula for mechanical advantage
MA = Fout/Fin
If mechanical advantage is less than 1 then input force is ______ and the machine is _____ at making work easier
greater than the output force
not good
If mechanicla advantage is greater than 1 the machines output force is _____. So…
greater than the input force
this would be a better machine at making work easier
Most simple machines make work easier by what is called a _____
Force-DIstance tradeoff
Force-DIstance tradeoff is when you _____ on the machine/object for a ______ to do the work needed. The force you put on the machine/object is ______ but ______
apply a force
longer distance
multiplied by the machine
only moves a small distance
A lever is a _____ that is free to pivot or turn around a ______
bar
fixed point
The fixed point the lever pivots on is the _____
fulcrum
Input arm of a lever is the distance from _____
the fulcrum to the point the input force is applied
Output arm is the distance from ______
the fulcrum to the output force
What is the IMA formula for a lever
IMA = Lin/Lout
The difference between the 3 classes of levers is the _____
location of the fulcrum, the input force, and the output force
In a first class lever the _____ is located in the middle
fulcrum
In a second class lever the _____ is located in the middle
output
In a third class lever the _____ is located in the middle
input
In a first class lever the output force is always…
in the opposite direction to the input force
What is an example of a first class lever?
seesaw
In a second class lever, the output force is always…
greater than the input force
What is an example of a second class lever?
wheelbarrel
In a third class lever the output force is always…
less than the input force
What is an example of a third class lever?
broom
anything you swing
(bat, golf club)
What type of lever is a car door
2nd
What were the first discovered simple machines
lever pulley screw
what was the last discovered simple machine
inclined plane
Who said “With a big enough lever and a place to rest it, a person could move the world”
Archimedes
A pulley is a ______ with a rope, cable, or chain running along the groove that is used to ______
grooved wheel
lift objects
A fixed pulley changes ______ of input force but does not _____ input force
direction
increase
A fixed pulley is a ______ lever
modified first class
Movable pulleys ______ input force
increase
A pulley in which one end of the rope is fixed and the wheel can move is what kind of pulley
movable pulley
A pulley that is attached to something that does not move is what kind of pulley
fixed pulley
A system of pulleys consisting of fixed and movable pulleys is what kind of pulley
block and tackle
What is the IMA of a fixed pulley
1
What is the IMA of a movable pulley
2
What is the IMA of a block and tackle
the number of rope segments supporting the weight
What is the IMA formula for a wheel and axel
IMA = rw/ra
a wheel and tackle is a simple machine consisting of a _____ attached to the _____ of a larger wheel so that the wheel and axle rotate together
shaft or axle
center
What is the fin and fout of a wheel and axle
fin: wheel
fout: axle
What is an example of a wheel and axle
door knob
steering wheel
What is the IMA formula for an inclined plane
IMA = l/h
( length of slope/height of slope)
An inclined plane is a sloping surface that _____ required to _____
reduces the amount of force
do work
What is an example of an inclined plane
wheelchair ramp
bike ramp
A screw is a ______ wrapped in a _____ around a cylindrical post
an inclined plane
spiral
What makes the IMA of a screw larger
when the threads are closer together
What are examples of a screw
screw, umbrella drill thing
What is the IMA formula for a wedge
IMA = l/w
A wedge is an ______ with 2 _____ sides
inclined plane
sloping
A wedge changes _____ of the input force
the direction
What is an example of a wedge
blade of knife, head of axe, end of scissors
why do we use machines
to make work easier
How do you make work easier
force-distance tradeoff
What do simple machines do
increase your force
change direction of your force
Machines make work easier or ______ by changing the ______ needed to do work
faster
force
Can machines increase the amount of work done
no
Fout can also be callled
load
Fin can also be called
effort
Can a machine increase your input force
yes
What are the 2 reasons why a machine is not 100% effective
friction
Any time energy changes forms efficiency is lost
What are the three ways machines are useful
changes direction of force
increases force
makes work faster
