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