Lesson 1Types of levers

The lever: Is a rigid bar that rotates around a fixed point called the fulcrum, and is affected by force and resistance.

Ice holder Manual broom Hockey bat

Tweezers Crowbar Nutcracker A set of pictures for some levers

Levers make the tasks perform more easily by doing one or more of the following functions:

1- Increasing force: As the crowbar and nutcracker. 2- Increasing distance: As the manual broom.3- Increasing speed: As in the hockey bat. 4-Moving the force from one place to another:As the manual broom.5-Accuracy in performance: As the tweezers 6-Avoid dangers: As the coal holder.

In the second class levers:The force of resistance is between the force of effort and the fulcrum.

The nutcrackers The soda-water opener The wheel barrow

Examples of second class levers

In the third class levers:The force of effort is between the fulcrum and the force of resistance.

The fish hook The manual broom The sweat holder

Examples of third class levers

ExerciseWrite the scientific term: - The fixed point of a rigid bar.- A rigid bar rotates on a fixed point, and is affected by a force and resistance. - Levers that have the fixed point between the force and the resistance. - Levers that have the fixed between the resistance and the fixed point.-Levers that have the resistance between the force and the fixed point.

Complete the following sentences: - Levers which make tasks perform more easily by means of ………., ………. or ……….

-The crowbar is considered a ………. class lever, but the manual broom is a ………. class lever.

- ………. and ………. are examples of the first class levers. - ………. and ………. are examples of the second class levers.

- ………. and ………. are examples of the third class levers.