http://session.masteringphysics.com/problemAsset/1...
A) How much work is done by the horizontal force Fp = 150 N on the 18kg block of the figure when the force pushes the block 4.0m up along the 32 degree frictionless incline?
B) How much work is done by the gravitational force on the block during this displacement?
C) How much work is done by the normal force?
D) What is the speed of the block (assume that it is zero initially) after this d is placement? [Hint: Workenergy involves net work done.]
Any help you can give is appreciated. Even detailed hints, formulas, and explaination to get me started would be awesome! Thanks.
2 Answers

http://hyperphysics.phyastr.gsu.edu/hbase/imgmec/...
A)
W = Fp cos 32 * 4 = 150 * 0.848 * 4 = 508.8 J
B)
W = m g sin 32 = 18 * 9.8 * 0.53 * 4 = 373.97 J
C)
Normal force = m g cos 32 + F sin 32 = 18* 9.8 * 0.848 + 150* 0.53 = 229.08 N
This force is perpendicular in the travel and its work W = 0 in the abscence of friction
C1)
F net = F cos 32  m g sin 32 = 150 * 0.848  18 * 9.8 * 0.53 = 127.2  93.49 = 33.71N
W = 33.71 * 4 = 134.84 J
D)
Acceleration  a = Fnet / m = 33.71 / 18 = 1.872 m/s2
Velocity block after 4m
e = 1/2 a t^2  t^2 = 2e / a = 8 / 1.872 = 4.27  t = √4.27 = 2.0668 s
velocity = a * t = 1.872 * 2.0668 = 3.869 m/s
http://hyperphysics.phyastr.gsu.edu/hbase/faia.ht...
Goodbye

for part B answer is Negative make sure that