Gina is driving her car to work, but she’s 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.

Question

Gina is driving her car to work, but she’s 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.

justjm · Answer

When there is an acceleration, that means that there is an unbalanced force applied in the direction of the acceleration.

In the vertical direction, nothing is moving up (let's just assume that it's not a flying car lol) so there's gravity pushing the car down and a normal force pushing back up. Hence the vertical direction would have a net force of 0

Yet in the horizontal dimensions, since the car has accelerated, the unbalanced force will have a net force that is...?

what do you think?