Force & Work Notes

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 force is any push or pull on an object.

work.

When a force is exerted that moves an object you do

The force must be in the same direction as the object’s motion.

Newtons.

The unit of measurement for force is

spring scale.

The tool used to measure weight or force is a

Joules.

The unit of measurement

for work is

W = F X d

Work = Force X distance

Work can be calculated using the following formula:

How much work is done if a force of 20 Newtons

moves a box 4 meters?

20N 4 m

W = F X d 20N 4 m

W = 20N X 4m

W = 80 Joules

Motion

The change in position of an object…

Machine

Device that makes effort seem easier…

Load or Resistance

Object to be moved…

Input force

Force you exert on a machine…

Output force

Force exerted by a machine…

Efficiency

Compares the amount of output force to the amount of force input.

3 ways machines can change force…

amountdirection

distance

Flat surface that slopes.

Inclined plane:

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

Examples:

Wheel with a rope, cable or

chain around it.

Pulley:

Can change the direction and the amount of the input force by increasing the distance over which the force is applied.

Examples: