How far can a mother push a 20.0 kg baby carriage, using a force of 62 N, if she can only do 2920 J of work? Question 3 options:
2 answers:
1) The correct answer is B. 47.09 m
In fact, the work done by the mother is
where F is the force she applied and d is the distance covered by the baby carriage. We are told that the maximum work she can done is , while the force she applies is F=632 N, therefore by rearranging the previous equation we find the distance travelled by the baby carriage:
2) The correct answer is B. 175 N.
As before, the work done is
where F is the force applied and d is the height at which the mass has been lifted. In this case, W=2100 J and d=12 m, therefore the force used is
3) The correct answer is B. 424 W.
The power is the ratio between the work done and the time taken, so we have:
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Answer:
0.237 (23.7 %)
Explanation:
The thermal efficiency of an engine is given by:
where
W is the useful work output of the engine
is the heat in input
Here we have:
and the work done is the total heat in input minus the heat exhausted:
So, the efficiency is
(23.7 %)