A person of mass 80 kg escapes from a burning building by jumping from a window situated 30 m above a catching net. The acceleration of gravity is 9.8 m/s2 . If air friction exerts a constant force of 100 N on her as she falls, determine her speed just before she hits the net:
1. 24.6495 m/s
2. 22.9396 m/s
3. 6.37868 m/s
4. 17.4299 m/s

Her speed just before she hits is 24.6495 m/s .

Explanation:

Given :

Mass of person , m = 80 kg .

Height from which it jumped , h = 30 m .

acceleration of gravity is , .

Force exerted by air friction , f = 100 N .

Now , force exerted by gravity is :

Therefore , net force experience by the body is :

Therefore , net acceleration of body is :

So by equation of motion :

So , her speed just before she hits is 24.6495 m/s .

Therefore , this is the required solution .

the part of the wave he is travelling on is the crest

the answer to this is proletariats.

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