In general,
Power = (energy moved) / (time to move the energy) .
If it's mechanical power, then
Power = (work done) / (time to do the work) .
If it's electrical power, then it can be any one of these:
Power = (volts) x (amperes)
Power = (volts)² / (resistance, ohms)
Power = (amperes)² x (resistance, ohms) .
Whatever kind of energy you're dealing with, power always
turns out to be
(amount of energy produced, used, or moved)
divided by
(time taken to produce, use, or move the energy) .
Answer: Work W = 0
Explanation: Work W = F·s. Because rock does not move, s = 0 and
work done is zero.
Answer: (b)0.000012/k
Explanation:
The linear expansion of the metal rod is given by
where
is the linear expansion
is the initial length of the rod
is the linear expansivity
is the increase in temperature
By re-arranging the equation, we find the linear expansivity:
