1. 14-3 Mechanical Advantage and Efficiency Answer on a separate sheet of paper
Objectives:
1. How does the actual mechanical advantage of a machine compare to its ideal mechanical advantage?
2. Why is the efficiency of a machine always less than 100 percent?

2. Mechanical Advantage
Mechanical advantage of a machine is the number of times that the machine increases an input force.
MA = Output force / Input force
MA = Input distance / Output distance

3. MA = ? MA = Id / Od Input Distance = 1.8 m MA = 1.8m / .3m
A woman drives her car up onto wheel ramps to perform some repairs. If she drives a distance of 1.8meters along the ramp to raise the car .3meters, what is the mechanical advantage?
MA = ?
Input Distance = 1.8 m
Output Distance = .3m
MA = Id / Od
MA = 1.8m / .3m
MA = 6

4. If you exert 100 N on a jack to lift a 10,000N car, what would the jack’s MA be?
Input Force = 100N
Output Force = 10,000N
MA = Of / If
MA = 10,000N / 100N
MA = 100

5. Efficiency
Efficiency is the percentage of the work input that becomes work output.
Because there is always some friction, the efficiency of any machine is always less than 100%.
Efficiency = (Work output / Work input) x 100

6. You have just designed a machine that uses 1000 J of work from a motor for every 800J of useful work the machine supplies. What is the efficiency?
Efficiency = ?
Work Output = 800 J
Work Input = 1000J
Efficiency = (Wo / Wi) x 100
Efficiency = (800 / 1000) x 100
Efficiency = 80%

7. Go back to the 14-3 Objectives and answer them again.
1. How does the actual mechanical advantage of a machine compare to its ideal mechanical advantage?
2.Why is the efficiency of a machine always less than 100 percent?