Question

You slide your friend with a mass of 65 kg out of the way as they are blocking the exit and keeping you from escaping from physics class where you have been tormented by problems for the last hour and a half. The coefficient of kinetic friction between the floor and your friend's shoes is 0.45 and you are able to push with 650N. How long will it take you to get your friend to their next class that is 35m down the hall from rest? (Answer: 3.5 seconds) I have worked the problem and checked my math. I get 1.99 seconds.

Answer 1

friction force = 65*9.81*.45 = 287 N

net force = 650-287 = 363 N

F = m a
a = 363/65 = 5.59 m/s^2

x = (1/2) a t^2
35 = .5 (5.59) t^2
t = 3.54 seconds

Answer 2

Thank you!