Elizabeth, with a mass of 56.1kg stands on a scale in an elevator. Total mass of elevator plus Elizabeth=850kg. As the elevator starts moving, the scale reads 450N. Find the acceleration and tension in the cable.

acceleration = 1.79 m/s^2

Tension = 6817 N

Explanation:

First let's find Elizabeth's weight:

Her weight is greater than the normal force (N = 450 N), so the elevator is going downwards.

The acceleration of Elizabeth is given by:

Where P is the weight of Elisabeth, N is her normal force, m is her mass and a is the acceleration. Then, we have that:

The tension in the cable is given by:

In this case, we use the total mass, so we have:

less than one you can't create energy

increase masses, decrease separation