Question

select the correct answer. gina is driving her car to work, but shes stopped at a red light. when the light turns green, she presses the gas pedal and accelerates (speeds up) to move the car. which of these statements is true the moment gina presses the gas pedal? assume the road is flat and level. a. the net force on the car is zero in the horizontal direction. b. the net force on the car is zero in the horizontal and the vertical directions. c. the net force on the car is greater than zero in the horizontal direction. d. the net force on the car is greater than zero in the vertical direction. e. the net force on the car is less than zero in the vertical direction.

Explanation:

Step1: Recall Newton's second law

According to Newton's second law $F = ma$, where $F$ is the net - force, $m$ is the mass and $a$ is the acceleration. When Gina presses the gas pedal, the car starts to accelerate horizontally.

Step2: Analyze the horizontal and vertical forces

In the vertical direction, the weight of the car $mg$ is balanced by the normal force $N$ from the road ($N - mg=0$), so the net - force in the vertical direction is zero. In the horizontal direction, since the car is accelerating (speeding up) horizontally, according to $F = ma$ and $a>0$ (horizontal acceleration), the net - force $F_{net,x}$ in the horizontal direction must be greater than zero.

Answer:

C. The net force on the car is greater than zero in the horizontal direction.