# A body weighing 100 kg lies on the floor of an elevator, which rises vertically upwards at an equal

A body weighing 100 kg lies on the floor of an elevator, which rises vertically upwards at an equal time with an acceleration of -2m / s². Determine body weight.

Given:

m = 100 kg – body weight;

a = -2 m / s ^ 2 – the acceleration of the elevator (directed downwards against the movement of the elevator);

g = 10 m / s ^ 2 – acceleration of gravity.

It is required to find P – body weight.

Since the force of gravity is directed downward and the acceleration is also directed downward, then Newton’s second law in this case will look like this:

– m * g + N = – m * a – where N is the support reaction force, numerically equal to the weight P. Then:

P = N = m * g – m * a = m * (g – a) = 100 * (10 – 2) = 100 * 8 = 800 N.

Answer: body weight will be 800 N.

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