Answer:
a. 14000
Explanation:
Given parameters:
Efficiency of the machine = 70%
Work done on machine = 20000J
Unknown:
Work done by machine = ?
Solution:
Efficiency of a machine is determined by;
Efficiency = [tex]\frac{Work done by machine}{Work done on machine} x 100[/tex]
70 = [tex]\frac{Work done by machine}{20000}[/tex] x 100
70 = [tex]\frac{work done by machine}{200}[/tex]
Work done by machine = 70 x 200 = 14000J