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# a 38.5 kg man is in an elevator accelerating downward. A normal force of 343 N pushes up on him. What is his acceleration?

### 3 Answers

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- FiremanLv 74 weeks ago
For downward motion of a lift:

=>F(net) = F(gravity) - F(applied)

As N = mg (Apparent) = F(net)

=>343 = 38.5 x 9.81 - 38.5 x a

=>a = 0.90 m/s^2 {downward}

- Steve4PhysicsLv 74 weeks ago
I'll take up as positive and use g = -9.81m/s².

His weight: W = mg = 38.5*(-9.81) = -377.685N

Resultant force on man: F = (-377.685) + 343 = -34.685N

F=ma gives:

a = F/m = -34.685/38.5 = -0.901 m/s² to 3 sig. figs.

So his acceleration is 0.901m/s² downwards.

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