Mary if riding her bike at a constant velocity of 10.2m/s. Suddenly someone jumps in front of her, 6 meters ahead of her. The coefficient of friction is 0.35, and her total mass is 130kg. She slams the breaks with 800N of force. Will she be able to stop in time?
I heard that the answer is yes as she stops in ~5.14m, but I do not know how.
m*g = 130kg * 9.8N./kg = 1274 N.
Fn = m*g = 1274 N.
Fk = u*Fn = 0.35 * 1274 = 446 N. = Force
of kinetic friction.
a = (Fap-Fk)/m = (-800-446)/130 = -9.58 m/s^2
V2^2 = V1^2 + 2a*d = 0
d = -V1^2/2a = -(10.2^2)/-19.17 = 5.43 m. = Stopping distance.
Note: The force applied is negative, be-
cause it opposes the motion.