Explanation:
Mass of boy = 40 kg
Mass of box = 20 kg
Total mass = 60 kg
Initial potential energy = 0 (since height would be 0 initially)
Final potential energy = mgh
Taking g as 10 m/s²,
=> 60 × 10 × 15
= 9,000 J
So, work done = final potential energy - initial potential energy
= 9,000 J
Power = Work/Time
=> Power = 9000/25
=> Power = 360 J/s
or 360 watt.
Please see pic, I'd solved in it.
This is a matter of plugging in. Specifically 7 for L.
T = 2πsqrt(7/32)
T = (6.28319...)(0.46771...)
T is about 2.93871 seconds
X = 5; 2(5) - 1 = 9. 4(9) = 36
