Solution:
We have,
Power [P] = 25000 Watt
Mass [m] = 6000 kg
Height [h] = 20 metres
Time [t] = ?
Now,
P = W/t = F x d/t = mxgx h/t
Or, 25000 = 6000 x 10 x 20/25000 [.......g = 10
m/s^2]
Or, t = 6000 x 10 x 20/25000
Or, t = 1200/25
Therefore, t = 48 second
Hence, the required time for the crane to lift the load is 48 seconds.
B. number of oscillations in a given period of time.
Answer:
Its period if its length is increased by a factor of four is 5 s.
Explanation:
The period of a simple pendulum is given by;

Given;
initial period, T₁ = 2.5
initial length, = L₁
new length, L₂ = 4L₁
the new period, T₂ = ?

Therefore, its period if its length is increased by a factor of four is 5 s.