Answer:
Efficiency = 71%
Explanation:
Given the following data:
Output energy = 250 Joules
Input energy = 350 Joules
To find efficiency;
Substituting into the equation, we have;
Efficiency = 71.43 ≈ 71%
Therefore, the efficiency of the candle is 71 percent.
Answer:
The velocity is 19.39 m/s
Solution:
As per the question:
Mass, m = 75 kg
Radius, R = 19.2 m
Now,
When the mass is at the top position in the loop, then the necessary centrifugal force is to keep the mass on the path is provided by the gravitational force acting downwards.
where
v = velocity
g = acceleration due to gravity
Explanation:
The given data is as follows.
mass (m) = 170 kg, Distance (s) = 9.6 m
Height (h) = 3.3 m, Force (F) = 1400 N
First, we will calculate the work performed by her as follows.
W = Fs
=
= 13440 J
Hence, minimal work necessary to lift the refrigerator is as follows.
U = mgh
=
= 5497.8 J
Therefore, we can conclude that he performed 5497.8 J of work.