Apulley stems has an efficiency of 65.1%. if you perform 350 j of work, how much useful work does the pulley perform?

a. 350 j
b. 301 j
c. 228 j
d. 122 j

C. 228 Joules

Efficiency of a machine is the energy or work output, divided by the energy or work input, and expressed as a percentage. An ideal machine would have an efficiency of 100%.

Efficiency = (work output/work input) × 100%

work input = 350 joules, efficiency = 65.1%

Work output = 350 j × 65.1/100

                    = 227.85

                    ≈ 228 Joules

kepler used the data from tycho blahe (his mentor) to construct the laws of planetary motion.