1. Simple Machines
Inclined Planes

2. Quick Review The UNITS for FORCE are NEWTONS!
We have used spring scales to measure this so far
The spring scales we have used measure 1N to 20N
The force YOU put into something is called the input force or EFFORT
The force the machine does is called the output force or the LOAD

3. Inclined Plane or Ramp
An inclined plane makes it possible to lift heavy objects using a smaller force
An inclined plane is a slanted surface used to raise an object.
A ramp is an inclined plane.
When an object is moved up an inclined plane, less effort is needed than if you were to lift it straight up, but, you must move the object over a greater distance.

4. A ramp is usually only useful for small inclines.
The steeper the angle of the ramp, the harder it is to control the motion of an object

5. Mechanical Advantage
The mechanical advantage of an inclined plane is: MA = output force (Distance the load is going) input force (height the effort needs to be applied for)
Distance that the load is going  Output force
Height the effort needs to be applied for  Input force

6. Examples MA = output force input force MA = 100 cm 20 cm MA = 5 100 cm

7. MA = output force input force
MA = 200 cm cm
MA = 20
200 cm
10 cm

8. MA = output force input force MA = 300 cm 75 cm

9. What does this mean?
All inclined planes will give a mechanical advantage but which are the best?
From our examples, it seems like the
ones that have less HEIGHT require less force
Ones that have more HEIGHT require more force

10. What if we use a pulley too?
A moveable pulley will DECREASE the amount of force needed to move an object up an inclined plane

11. Friction We have NOT considered FRICTION
Friction occurs whenever two surfaces rub against one another
Friction is the force that goes against (opposes) motion

12. A rough surface creates more friction than a smooth surface
THIS MEANS: Extra force is needed to overcome friction when you move an object
This can affect our mechanical advantage.
What happens when two object rub against one another?
It creates HEAT!

13. Examples of Friction
When a driver wants to stop a vehicle, friction is created where?
When you are writing notes in science class, friction is created where?
Where would there be greater friction, writing with pencil or with pen?