Using Machines 1 Machines A machine is a

Using Machines

1. Machines § A machine is a device that makes doing work easier. § Machines make work easier by § § § (a) increasing force (b) increasing distance ‘(c) changing direction

2. Effort Force § Effort force is the force applied to the machines § Fe

3. Resistance Force § Resistance force is the force applied by the machine to overcome resistance § Fr

4. Work Done by a Machine § Two types of work: the work done by you on the machine and the work done by the machine § Input Work: Win – work done by you on the machines § Output Work: Wout – work done by the machines

5. Conserving Energy § Recall, energy can not be created or destroyed; it is transferred § So, Wout can NEVER be greater than Win; typically Wout is always less than Win because some of the energy changes to heat due to friction

6. Ideal Machines § No friction exists and therefore § Work in ==== Work out

7. Mechanical Advantage § Mechanical Advantage – the number of times a machines multiplies the effort force § Calculated by dividing the Resistance Force by the Effort Force

8. IMA vs MA § Difference between ideal mechanical advantage and mechanical advantage is friction. § IMA is a calculation assuming no work input is lost to friction and converted to heat. § MA takes friction into account and is a realistic number.

9. Efficiency § Efficiency is a measure of how much of the work put into a machine is changed into useful output work by the machines (ie not transferred to heat via friction) § Wout/Win * 100%