another problem :(

a car if nass 1600kg coast down a 10 percent grade from A to B, a distance of 30m and then coast along a level road until it stops at C. assume the road resistance to remain constant of 200N for the entire distance A to C, if the initial velocity of the car at A is 25kph, compute:

a.) its velocity at B
b.) the distance s it coast from B to C.

Motion from A to B

EA - Friction Work = EB
[12(1600)(253.6)2+1600(9.81)(30101)]200(30)=EB

EB=79,434.56 Nm

12(1600)(vB3.6)2=79,434.56

vB=35.87 kph

 

win_20150421_094416.jpg

 

Motion from B to C

EB - Friction Work = EC
79,434.56200sBC=0

sBC=397.17 m