Aperson is on an elevator that moves
downward with an acceleration of
1.8 m/s ? . if the person weighs 686 n,
what is the net force on the person?

The net force acting on the person is, F = 560 N

Explanation:

Given data,

The downward acceleration of the elevator, a = 1.8 m/s²

The weight of the person is, W = mg

                                                          = 686 N

Therefore the mass of the person,

                                           m = W /g

                                               = 686 / 9.8

                                               = 70 kg

The net force acting on the person,

                                           F = mg - ma

                                               = 686 - 70 x 1.8

                                               = 560 N

Hence, the net force acting on the person is, F = 560 N

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.