Question

An elevator is raised by a cable, as shown in the diagram. If the mass of the elevator is 715 kg and the tension in the

cable is 8000 N, what is the upward acceleration of the elevator, in units of m/s2

Answer 1

1.379 m/s2

Step-by-step explanation:

F=ma

There is a negative force from the elevator...

F = (715 kg) (-9.81 m/s2)

F = -7014.15 N

Cable + elevator = 8000 N + (-7014.15 N)

F = 985.85 N

a = F/m

985.85 N/715 kg = 1.379 m/s2

Answer 2

First find the weight of the elevator by doing mass*gravity. It’s 7007 N. So now find the net force on the system by adding the vertical components of the force. We have a positive 8000 N from the tension plus a negative 7007 N from the weight of the elevator.

Net force:
8000 N - 7007 N = 993 N
Now do 993 N = ma
993 N / 715 kg = 1.39 m/s^2