Science Chapter 3
Efficiency is represented by BLANK
%
The amount of work done by applying 1 Newton of force over a distance of 1 meter
1 Joule
Machines can make work easier in BLANK ways
3
There are BLANK classes of levers
3
Only changes direction of force. The 2 sides of the pulley are the input arm and output arm Ex. Crane
Fixed pulley
Distance from the fulcrum to the point where the output force is exerted by the lever
Output arm
Power equation
P=w divided by t
The rate at which work is done
Power
Grooved wheel with a rope, chain, or cable running along the groove
Pulley
An inclined plane wrapped in a spiral around a cylindrical post. The threads on it form a tiny ramp that runs up from the tip
Screw
The transfer of energy that to an object by a force that makes an object move in the direction of the force
Work
Uses the distance that the force acts on the object not necessarily the distance the object moves
Work Equation
Efficiency equation
Wout=eff x Win eff= efficiency Wout= output work Win= input work
Kinetic energy
energy in motion
If a machine's output is equal to the input, the mechanical advantage is BLANK because it is a ratio
equal
A mechanical advantage equal to 1 means the input force and the output force are BLANK, but the direction of the input force BLANK
equal changes
The weight of any object is due to the downward force of BLANK on the object
gravity
A mechanical advantage BLANK than 1 means the output force of greater than the input
greater Ex. 6 <--the output is greater 1
The Inclined Plane family
inclined plane, screw, and wedge
Time units
seconds
Machine change the way BLANK is done
work
The ratio of the output produced to the input force applied
Mechanical Advantage
Joule; unit of work
Newton-meter; kg x m^2 s^2
What factors determine the difference between a 1st, 2nd, and 3rd class lever
The input force to the output force, the fulcrum, and the mechanical advantage
Material used on machine parts to reduce friction
any type of lubricant
Usually, on a wheel and axle, the input force is applied to the BLANK, the output force is exerted by the BLANK
wheel axle
There are BLANK simple machines
6
Describe 2 ways in which energy in an object is changed when it is lifted
Because work if being done when it is being lifted. Also, because of the kinetic energy
System of pulleys consisting of both fixed and movable pulleys Ex. some workout machines
Block and Tackle
2 or more simple machines that operate together
Compound Machine
The ratio of the output work to the input work
Efficiency
Because the output work is always less than the input work, the BLANK of a machine is always less than 100% because of BLANK
Efficiency; friction. You can get more force with mechanical advantage but you are not getting more work than you put in
Mechanical Advantage equation
Fout= MA x Fin Fout= output force MA= mechanical advantage Fin= input force
Fixed point that the lever pivots on
Fulcrum
How does the input force applied by a large gear change when the force is applied to a smaller gear
If the smaller gear has the same input force, it rotates more and goes faster because it is smaller. The input force reduces friction
Sloping surface, such as a ramp. It reduces the amount of force required to work
Inclined Plane
Distance from the fulcrum to the point where the input force is applied
Input arm
A bar that is free to pivot or turn on a fixed point
Lever
BLANK must occur for work to be done
Motion
One end of the rope is fixed, leaving the wheel free to move Ex. Zip line
Movable pulley
Force units
Newtons/kg x m/s^2
How does moving an object affect work
The force must be done in the direction of motion in order for work to be done
How does moving an object at a different angle affect work?
The force used to calculate work is in the direction of motion.
1st Class Lever
The input and output are in opposite directions; Example: see saw, scissors
2nd Class Lever
The input and output are in the same direction; Example: wheel barrow, crow bar, door
3rd Class Lever
The input and output both go down; Example: a baseball bat, shovel, and fishing rod
1 unit of power is equal to 1 Joule of work per second of time
Watt
An inclined plane with 1 or 2 sloping sides. It changes the direction of the input force. Ex. knife, front and back teeth when biting into an apple. The downward input force is changed to a horizontal force
Wedge
Consists of a shaft or axle attached to a wheel Ex.: mechanical pencil sharpener, door knob, faucet handle
Wheel and Axle
Machines don't BLANK the amount of work required
decrease
When changing the distance, the output force exerted by any machine BLANK, the output distance BLANK
decreases increases
A machine can make it easier to do work by changing the BLANK of the input force
direction
The work done on an object depends on the BLANK of the force applied and the direction of BLANK
direction motion
A machine can make it easier to do work by changing the BLANK over which the force acts
distance Ex.: a shuffleboard, rake
Doing work on an object transfers BLANK to the object
energy
To use a machine, you must apply a BLANK to it
force
2 things to calculate work
force and distance
When a hammer removes a nail: the input force comes from the pulling on the BLANK, the hammer changes this to an output force that........
hammer's handle pulls the nail out of the board
Some machines BLANK the size of the input force, whereas others BLANK it
increase decrease
When you use a machine, the BLANK force makes part of the machine move
input
A machine changes the BLANK to the BLANK
input output
Work is done because the BLANK causes movement
input force
The output work done by a machine never exceeds the BLANK BLANK of the machine
input work "you can't get more than you give"
Newtons
kg x m s^2
Watts
kg x m s ^3
Joule
kg x m^2 s^2
Because doing work on an object makes it move, doing work on the object increases its
kinetic energy
When changing the size, a machine can change the input to a BLANK output
larger
A mechanical advantage BLANK than 1 means the output force is less than the input
less Ex. 1 <--the input is less 6
The Lever family
lever, pulley, and a wheel and axle
A device that makes doing work easier
machine
Any device that makes something easier
machine
Distance units
meters
Doing work on the object causes it to BLANK
move
When a force is applied to an object, no work is done unless it BLANK
moves
A weightlifter does work when exerting a force that makes weights move, but does no work to hold weights in place because the weights are not BLANK
moving
To calculate the overall efficiency of a compound machine you...
multiply the efficiencies
Product of the output force and the distance over which it acts
output work
Lifting an object increases the object's gravitational BLANK energy
potential
Increasing the height of an object by lifting it increases what
potential energy
With a rake, your hands move through a BLANK distance, but the other end of the rake moves through a BLANK distance
shorter greater
When changing the size, the output force acts over a BLANK distance than the input force does
shorter Example: crowbar, back of a hammer
A machine that does work with only 1 movement of the machine
simple machine
A machine can make work easier by changing the BLANK of the force
size
Potential energy
stored energy
Power equation
w=P x t w= work P= power t= time
Work equation
w=f x d w= work f= force d= distance
Power units
watts
To lift an object, you must pull upward on the object with a force equal to the its BLANK
weight