Work The amount of energy transferred by a force over a certain distance Measured in joules If an object doesn’t move a distance, no work was done W=FxD

Work= Force multiplied by distance How much work is done by a person who pushes a lawnmower with a force of 50N at a distance of 450m? 55,000 J of work is done to move a rock 25m. How much force was applied?

Simple Machines -make work easier by changing the size or direction of a force -you do work on the machine, the machine does work on something else -Mechanical advantage is the number of times the machine multiplies your force. https://www.youtube.com/watch?v=yhzMYHiuEC4

Lever Made up of a bar that pivots on a fulcrum Change in direction makes work easier

Wheel & Axle Wheel attached to an axle Force is transferred from one to the other Axle moves faster than the wheel making work easier

pulley A pulled rope over a wheel Changes the direction of the force Increases the applied force making work easier

Inclined plane Flat surface raised at an angle like a ramp Used for lifting heavy loads instead of straight up The increased distance decreases the force required

Wedge Two inclined planes put together Two planes form a sharp edge Used to push objects apart or cut The thinner the wedge, the easier the work

Screw A spirally grooved cylinder An inclined plane wrapped around a cylinder The less distance between the threads, the easier the work

Compound machines 2 or more simple machines working together

Simple Machine Video https://www.youtube.com/watch?v=fvOmaf2GfCY

1st class lever Fulcrum placed between the effort and load Example: Seesaw

2nd class lever Load in between the effort and the fulcrum Example: Wheelbarrow

3rd class lever Effort in between the load and the fulcrum Example: Baseball bat

The mighty mathematics of a lever https://www.youtube.com/watch?v=YlYEi0PgG1g&t=14s