Simple machines

They decreases our applied force. Making work easier. But do not reduce amount of work

1. Lever

LEVER

1st class lever

Scissors Can opener

Crowbar

Mechanical advantage of simple machine

Find effort

Lever 120 cm long used to move 80 kg load Lever 120 cm long used to move 80 kg load . From load to the fulcrum is 30 cm Find effort

2nd class lever

Wheelbarrow

Nutcracker

Bottleopener

Load 60 kg Find force Find mechanical advantage

In 2nd class lever load 150 N is holded by 25 N Load distance from fulcrum 30 cm Find effort distance and mechanical advantage

3rd class lever

2N is applied effort distance 5 cm. Length of sugar tong is 10 cm. Find the mass of sugar

Find effort distance(2 cases…1 weight of rod is 0…2 weight of rod is 40 N)

Practice problems Page 122 solve the following problems

2. Pulley

Fixed Pulley

Movable pulley

Combination of pulleys Combinations of pulleys

Load is moved by 10 m Find how far was the rope pulled

If our force is 200 N. What is weight of an object??

3. Wheel and axle

4. Inclined plane

5. Screw

Pitch

42 turns 60 cm goes up Find pitch

The length of a screw is 5,6 cm. Pitch is 0,8 mm The length of a screw is 5,6 cm. Pitch is 0,8 mm. After how many turns will it penetrate totally to the wood

6. Wheels and gears

N*R=n*r

Gear

Gear

1st makes 10 revolutions

Practice problems Page 123 Answer the test questions 1-15