A granite block of mass 1000kg is given an initial speed of Vo=25.0m/s up a hill
ID: 2258246 • Letter: A
Question
A granite block of mass 1000kg is given an initial speed of Vo=25.0m/s up a hill that makes an angle of theta=30.0 with respect to the horizontal. The coefficient of kinetic friction between the block and the hill is Fk=0.300. Ignore air resistance.
a. What is the acceleration, a, of the block on the incline?
b. What distance, L, will the block travel up the hill before coming to a momentary stop?
c. The coefficient of static friction between the block and the hill is Ms=0.600. Will the block move back down the hill once it comes to a stop? (show work)
Explanation / Answer
a)
a = -g*sin(30) - mue*g*cos(30)
a = -7.44 m/s^2
b) v2^2 - v1^2 = 2*a*L
here, v2 - 0, v1 = 25 m/s
==> L = -v1^2/(2*a) = 42 m
c)
Fg = m*g*sin(30) = 4900 N
Ff(max) = m*g*mue*cos(30) = 5092.3 N
maximum static frcition force is greater than Fg, so it remains in rest there itself.