Question 3 (20%). A 20kg bulldog stands on
a skateboard rolling down an inclined track
as shown in the picture. He begins at a
height of 15 meters at rest.
A) At the bottom of the track, at a height of 3
m, how fast is the dog going? (Ignore any
friction on the track)
15m
30$^\circ$
3m
H
B) Suppose the frictionless track was replaced by a longer one, so that the bulldog went from the
15 m to the 3 m point at an angle of 10 degrees to the horizon (instead of 30 as in the picture).
Would that change the speed of the bulldog at the 3 m height? You must explain your answer
to get credit here.
C) Would your answer to part B be different if, instead of a frictionless track, there was a constant
friction force of 3N acting on the skateboard? (This would be accomplished by having the less-
steep track of part B be smoother than in part A). You must explain your answer to get credit
here.
