Question

a toy car rolls straight at a constant speed on a smooth track. what is the net force on the car?
zero (forces are balanced)
forward
backward
upward

Explanation:

Step1: Recall Newton's first law

An object moving at a constant speed in a straight - line has no acceleration. According to Newton's second law $F = ma$ (where $F$ is net force, $m$ is mass and $a$ is acceleration).

Step2: Determine acceleration value

Since the speed is constant, acceleration $a = 0$.

Step3: Calculate net force

Substitute $a = 0$ into $F=ma$. We get $F=m\times0 = 0$. So the net force on the car is zero, which means the forces acting on it are balanced.

Answer:

Zero (forces are balanced)