a 1300 kg car starts from rest at A , coasts 170m through a dip and comes to stop at B after coasting a distance d on level ground . if the rolling resistance is a constant force of 220N , determine the distance d .
3 answers
Since there is no kinetic energy change from start to finish and zero energy added by the coasting engine, the potential energy change equals the rolling resistance times the distance travelled. A figure is needed to show the length and depth of the "dip". Is there rolling resistance loss before the level portion?
170m length dip and dips down 12m at the very bottom and up 5m to level ground. Distance =?
Kinetic energy gained passing through dip = M*g*(12-5) - 170*220
= 89180 - 37400
= 51,780 J
This is converted to rolling friction work after the dip
51,780 = 220*d
d = 235 m
= 89180 - 37400
= 51,780 J
This is converted to rolling friction work after the dip
51,780 = 220*d
d = 235 m