A 4.0 kg block is pushed 2.0 m at a constant velocity up a vertical wall by a constant force applied at an angle of 30.0◦ with the horizontal, as shown in the figure. The acceleration of gravity is 9.81 m/s². If the coefficient of kinetic friction between the block and the wall is 0.20, find:
a) the work done by the force on the block.
Answer in units of J
b) the work done by gravity on the block.
Answer in units of J.
c) the magnitude of the normal force between
the block and the wall.
Answer in units of N.

d eras and periods

answer: the potential energy decreases from 379 j to 243 j

explanation:

for the law of conservation of energy, the total energy in a system must be conserved. the total energy of the system is given by the sum of kinetic (k) and potential (u) energy:

e = k + u

the total energy is e=675 j, and this does not change.

initially, the kinetic energy is k=296 j, so the potential energy is

at the end, the kinetic energy is k=432 j, so the potential energy is

so, we see that the potential energy has decreased from 379 j to 243 j.