Question

what are three ways a driver can cause a car to accelerate?
a. turn the key in the ignition of a stopped car to start it.
b. press the brake pedal while the car is moving.
c. press the gas pedal of a stopped car to make it move.
d. turn the steering wheel while the car is moving.

Explanation:

• Option A: Turning the key in the ignition of a stopped car to start it is just the act of starting the vehicle's engine. It doesn't directly cause acceleration (a change in velocity).
• Option B: Pressing the brake pedal while the car is moving causes deceleration (negative acceleration) as it reduces the car's speed.
• Option C: Pressing the gas pedal of a stopped car to make it move. When the gas pedal (accelerator) is pressed, the engine provides more power to the wheels, and if the car is moving from rest (stopped), its velocity changes (increases), which is acceleration.
• Option D: Turning the steering wheel while the car is moving changes the direction of the car. According to the definition of acceleration (\(a=\frac{\Delta\vec{v}}{\Delta t}\), where \(\vec{v}\) is velocity, a vector quantity), a change in direction (even if speed is constant) means a change in velocity (since velocity has both magnitude and direction), so this is a form of acceleration (centripetal acceleration in the case of circular - like motion from turning).

Answer:

C. Press the gas pedal of a stopped car to make it move; D. Turn the steering wheel while the car is moving.