Answer:
Efficiency = 77%
Explanation:
Input energy = 570 J
Output energy = 440 J
To find the efficiency;
Substituting into the equation, we have;
Efficiency = 77.19 ≈ 77%
Therefore, the efficiency of the engine is 77 percent.
If a 12-N force is applied continuously through a distance
of 12m, then the amount of work done is
(force) x (distance) = (12 N) x (12 m) = 144 joules.
Power = (work done) / (time to do the work)
= (144 joules) / (3 sec) = 48 joules/sec = 48 watts.
We don't care what purpose the force was used for,
or how much friction was involved.
First, we must find the vertical distance traveled upwards by the ball due to the throw. For this, we will use the formula:
2as = v² - u²
Because the final velocity v is 0 in such cases
s = -u²/2a; because both u and a are downwards, the negative sign cancels
s = 14.5² / 2*9.81
s = 10.72 meters
Next, to find the time taken to reach the ground, we need the height above the ground. This is:
45 + 10.72 = 55.72 m
We will use the formula
s = ut + 0.5at²
to find the time taken with the initial velocity u = 0.
55.72 = 0.5 * 9.81 * t²
t = 3.37 seconds