newton's law
posted by jack on .
A block of mass M is projected up a frictionless inclined plane with a speed VO. The angle of incline is given as theta.
a. How far up the plane does it go?
b. How much time does it take to get there?
I was stuck after Fg(cos(theta+90)= Ma_x
gcos(90+theta)/M = a_x
can someone please help me

kinetic energy at bottom = (1/2) M Vo^2
= potential energy at to when it stops
= m g h = M g (x sin theta)
so
(1/2) M Vo^2 = M g x sin thets
x = Vo^2/(2 g sin theta)
average speed = Vo/2
time = distance/average speed
= Vo^2/(2 g sin theta)] / [ Vo/2)]
= Vo/(g sin theta) 
thanks but my instrutor don't want me to use energy to solve the problem since we havnt learn it yet, can you do it using newton's law?