inclinced planes?

Question

1.)A 10-kg crate and a 100-kg crate are both sliding without friction down a plane inclined at 20 degrees with the horizontal. What is the acceleration of each crate?

2.)A box slides down a frictionless plane that makes an angle of 35 degrees with the horizontal. A horizontal force of half the box's weight process the box against the plane. what is the boxes acceleration?

Answer 1

1.
F(downward ) = mg sin (angle of the incline)
a=F/m
a1=F1/m1=m1 g sin (20)/m1
a1=g sin (20) (the acceleration is independent of the mass)

where
g=8.91m/sec^2
2. from the part 1
a = g sin(35)
if F=.5mg
a=F/m=.5mg/m=g/2