Physics...HELP...I TRIED AND FAILED MISERABLY...?

Question

1.) A 66 kg person escapes from a burning building by jumping from a window 25 m above a catching net.
Air resistance exerts a 95 N force on the person during the fall.

Determine the person's velocity just before hitting the net.

I've tried lots of different formulas (obviously not the right ones) and keep getting two answers (22.1 and 20.4) each time, and they're both wrong. Please help; I don't know what I'm doing wrong.

2.) A block with a mass of 5 kg is held in equilibrium on an incline of angle 30.0° by the horizontal force, F. Find the magnitude of F.

This one is mind boggling. I really don't understand how to do any of it. And don't be all like, "do your own work," cause I'm asking for help, not answers.

Thanks.

Answer 1

1. Net accel a = g - air res. accel 95/m.
Then use the formula h = v^2/(2a) (derived from the more familiar h = at^2/2) which yields v = sqrt(2ah).
2. It helps to draw a picture. The grav. force along the ramp = mg sin(theta) and the hor. force component along the ramp = F cos(theta). These forces are equal (no friction). Then F/mg = sin(theta)/cos(theta) = 1/tan(theta).