Gravitational potential energy = mass x acceleration due to gravity x height
GPE=mgh
4620=mx9.81x8.4
4620/(9.81x8.4)=m=56.1 kg
A, hope this helped! I didn’t really get it but I think it’s correct?
Answer:
Acceleration will be equal to
Explanation:
We have given mass of the object m = 0.4 kg
Spring constant k = 8 N/m
Maximum displacement of the spring is given x = 0.1 m
From newton's law force is equal to
.....eqn 1
By hook's law spring force is equal to
.....eqn 2
From equation 1 and equation 2



So acceleration will be equal to 
Answer:
0.1 rev/s
Explanation:
M = mass of the merry go round = 200 kg
R = radius of merry go round = 6 m
= Moment of inertia of merry go round = (0.5) MR² = (0.5) (200) (6)² = 3600 kgm²
m = mass of the man = 100 kg
= Moment of inertia of merry go round when man sits on it at the edge = (0.5) MR² + mR² = (0.5) (200) (6)² + (100) (6)² = 7200 kgm²
= initial Angular speed of merry-go-round before man sit = 0.2 rev/s
= Angular speed of merry-go-round after man sit = ?
Using conservation of angular momentum
=
(3600) (0.2) = (7200)
= 0.1 rev/s