At a given instant in time, a 18-kg rock is observed to be falling with an acceleration of 7.75 m/s2. what is the magnitude and direction of the gravitational force on the rock?

36.9 N

Explanation:

m = 18 kg

a = 7.75 m/s^2

g = 9.8 m/s^2

F = mg - ma = 18 (9.8 - 7.75)

F = 18 x 2.05 = 36.9 N

The gravitational force acting on the rock is 36.9 N.

scientific laws are the result of testing theories and proving them to be facts.

there are no contact forces mentioned on the list of choices that you've provided.