Answer:
η = 58.8%
Explanation:
Work is defined as the force applied by the distance traveled by the body.
where:
W = work [J] (units of joules)
F = force = 294 [N]
d = distance = 5 [m]
Efficiency is defined as the energy required to perform an activity in relation to the energy actually added to perform some activity. This can be better understood by means of the following equation.
Answer:
V = - 0.5 [m/s]
Explanation:
In order to solve this problem, we must use the principle of relative speeds. This is for an observer who is on the edge of the river he can see how the river moves to the left and the woman tries to move to the right but can not since:
That is, the person sees how the woman moves to the left but with avelocity of 0.5 [m/s] to the left
Answer:
4.163 m
Explanation:
Since the length of the bridge is
L = 380 m
And the bridge consists of 2 spans, the initial length of each span is
Due to the increase in temperature, the length of each span increases according to:
where
is the initial length of one span
is the temperature coefficient of thermal expansion
is the increase in temperature
Substituting,
By using Pythagorean's theorem, we can find by how much the height of each span rises due to this thermal expansion (in fact, the new length corresponds to the hypothenuse of a right triangle, in which the base is the original length of the spand, and the rise in heigth is the other side); so we find: