Question

A 62kg person escapes from a burning building by jumping from a window 17.5m above the rescue net. Assuming air resistance provides a constant 45N force during the fall, at what speed does the person hit the net?

Answer 1

The person hits the net with a speed of approximately 23 m/s.

Step-by-step explanation:

To find the speed at which the person hits the net, we can use the principle of conservation of energy. At the window, the person only has potential energy, given by the formula PE = mgh, where m is the mass, g is the acceleration due to gravity, and h is the height.

We can calculate the potential energy as follows: PE = (62kg)(9.8m/s^2)(17.5m) = 10807 J.

When the person hits the net, all of their potential energy is converted into kinetic energy. Therefore, we can equate the potential energy to the kinetic energy using the formula KE = 1/2mv^2, where v is the velocity.

So, 10807 J = (1/2)(62kg)v^2. Solving for v gives us v = sqrt((2 * 10807 J) / 62kg) ≈ 23 m/s.

Therefore, the person hits the net with a speed of approximately 23 m/s.