Answer:
a) 60 N
b) 860 N
Explanation:
Given that,
= 100 kg
= 20 kg
= 8.0 
= 3.0 
a) By Newton's Law,
∑
∑
Hence,

b) By Newton's Law
∑
Hence,

Net force acting on 100 kg mass,

The work done to "HOLD" a load of bricks at any height is zero.
Work is done only when force acts through a DISTANCE.
The work done to LIFT 30 kg of anything to 20m higher than
it already is, is
(force) · (vertical distance)
= (mass) · (gravity) · (vertical distance)
= (30 kg) · (9.8 m/s²) · (20 m)
= 5,880 joules
People have diffrent body builds and bone structure
When an earthquake strikes usually seismic waves carry the energy outward (a.) With the greatest power at the focus and as the seismic waves travel outward they become more and more weak until they disappear.<span />