Simple Machines Inclined Planes
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
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.
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
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
Examples MA = output force input force MA = 100 cm 20 cm MA = 5 100 cm
MA = output force input force MA = 200 cm 10 cm MA = 20 200 cm 10 cm
MA = output force input force MA = 300 cm 75 cm
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
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
Friction We have NOT considered FRICTION Friction occurs whenever two surfaces rub against one another Friction is the force that goes against (opposes) motion
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!
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?