You push with an applied force of 27 N on a 10 kg box across a table, and there is a 7 N force of friction. a) How fast will the box accelerate?

b) What is the coefficient of friction between the box and the table?

b. a lightning bug, plug of grass, and a worm

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.