(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

An elevator containing three passengers (with a mass of 72kg, 84kg, and 35kg, respectively) has a combined mass of 1030kg. The cable attached to the elevator exerts an upward force of 12 000N, but friction opposing the motion of the elevator is 1400N.

a) Calculate the net acceleration of the elevator and its passengers.

I started by calculating F(net).

F(net) = 12 000N - (Ff + Fg)

F(net) = 12 000N - (1400N + (1030kg * 9.80m/s^2))

F(net) = 506N

Now, to calculate net acceleration:

a(net) = F(net) / m

a(net) = 506N / 1030kg

a(net) = 0.49m/s^2

Is that correct? That seems realistic for an elevator (I think).

b) Calculate the force normal acting on the 35kg passenger.

Fn = mg - ma

Fn = (35kg)(9.80m/s^2) - (35kg)(0.49m/s^2)

Fn = 325.85N

Am I doing this properly so far?

c) What velocity will the elevator have 12 seconds after the passengers have entered the elevator?

v = a * t

v = 0.49m/s^2 * 12s

v = 5.88m/s

Can anybody verify if this is correct? It would be much appreciated!

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# Homework Help: Basic Frictional Forces/Gravity Question

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