A 5 kg book rests on a table. How much force is it exerting on the table?

(Hint: think about acceleration due to gravity.)

49N

Explanation:

Basically, think of this problem as asking how much the book weighs, as that is all weight is, how much force you exert on whatever surface you're on.

Thus, the force due to gravity Fgrav = mg = 5 * 9.8m/s^2 = 49N.