Explanation:
If g= 10m/s²
Then 75kg=75×10=750N
Since Work =Force ×Distance
Work=750×30
=22500J
And Power°=Work÷time
=22500÷120
=187.5W
Answer:
(1) 0.333 Hz
(2) 4 sec
(3) 2 sec, 0.5 Hz
Explanation:
(1) We have given time period of pendulum is 3 sec
So T = 3 sec
Frequency will be equal to 
(2) Frequency of the pendulum is given f = 0.25 Hz
Time period is equal to 
(3) It is given that a pendulum makes 10 back and forth swings in 20 seconds
So time taken to complete 1 back and forth swings = 
So time period T = 2 sec
Frequency will be equal to 
Answer:
P = 11666.6 W
Explanation:
Given that,
Work done by the motor, W = 3500 kJ
Time, t = 5 min = 300 s
We need to find the power developed by the motor. Power developed is given by :

So, the required power is 11666.6 W.
You know the following:
k= 25N/m
x=1.5m
Now you just plug these numbers into the formula which is
Epe = 1/2kx²
= 1/2(25N/m)(1.5m)²
= 28.125J or in proper sigdigs 28J
Hope this helps!