Question

a 75kg man stand in a lift what force does exert on it when the elivater start moving upward with an acceleration 2m/s

Answer 1

Let the force that the lift applies on it, be R


The force that the man will apply on it, will be mg (mass × acceleration due to gravity) and it would be downward. So, R would be upward to maintain the equilibrium.

When the lift is moving upwards, the net force would be upward. So, R would become > mg.

So net force = R - mg

And net acceleration = a
=> net force = ma

Equating the two,

R - mg = ma

=> R = ma + mg

=> R = m(a + g)

So, m = 75, a = 2, taking g as 10m/s²

R = 75(2 + 10)

=> R = 75 × 12

=> R = 900 N

So the lift will apply a force of 900 N on the man.

Answer 2

Answer:

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