Force & Work Force & Work NotesNotes

TEKS 6.8E investigate how inclined planes and pulleys can be used to change the amount of force to move an object

TEKS 7.7A contrast situations where work is done with different amounts of force to situations where no work is done such as moving a box with a ramp and without a ramp, or standing still

A A forceforce is is any push or any push or pull on an pull on an

object.object.

work.work.

When a force When a force is exerted is exerted that that movesmoves an object you an object you dodo

The force The force must be in must be in the the samesame direction as direction as the object’s the object’s motionmotion..

Newtons.Newtons.

The unit of The unit of measurememeasurement for force nt for force

is is

spring spring

scale.scale.

The tool used The tool used to measure to measure weight or weight or force is a force is a

JoulesJoules..

The unit of The unit of measurememeasurement for work nt for work

is is

W = F X dW = F X d

WWorkork == FForceorce XX ddistanceistance

Work can be Work can be calculated using calculated using the following the following formula:formula:

How much work is How much work is done if a force of 20 done if a force of 20

Newtons moves a box Newtons moves a box 4 meters?4 meters?

20N 4 m

W W = F X d= F X d 20N 4 m

WW == 20N20N XX 4m4mWW == 80 80 JoulesJoules

MotionMotion

The change The change in position in position of an of an object…object…

MachinMachinee

Device that Device that makes makes effort seem effort seem easier…easier…

Load or Load or ResistanResistancece

Object to Object to be moved…be moved…

Input Input forceforce

Force you Force you exert on a exert on a machine…machine…

Output Output forceforce

Force Force exerted by a exerted by a machine…machine…

EfficiencyEfficiency

Compares the Compares the amount of amount of outputoutput force to the amount force to the amount of force of force inputinput..

3 ways machines 3 ways machines can change can change forceforce……

amountamountdirectiondirectiondistancdistancee

Flat surface Flat surface that slopes.that slopes.

Inclined Inclined plane:plane:

Less Less input forceinput force needed to move an needed to move an object, but it must object, but it must be moved over a be moved over a greater greater distancedistance. .

Examples:Examples:

Wheel with a Wheel with a rope, cable or rope, cable or chain around chain around

it.it.

Pulley:Pulley:

Can change the Can change the directiondirection and the and the amount amount of the input of the input force by increasing force by increasing the the distancedistance over over which the force is which the force is applied.applied.

Examples:Examples: