You are driving in your car and you apply a constant force to your brake pedal. Which of the following are changing? (Ignore air resistance)
a. Speed
b. Velocity
c. Acceleration
d. Speed and Velocity
e. All of the above
d. speed and velocity
The correct answer is: e. All of the above.
When a constant force is applied to the brake pedal of a car, the car undergoes deceleration (negative acceleration). As a result, the car's velocity decreases, causing both the speed and velocity to change.
To determine which quantities are changing, we need to understand the relationships between them.
Speed is a scalar quantity that only refers to the magnitude of an object's motion. It is calculated as the distance traveled per unit of time.
Velocity is a vector quantity that includes both the magnitude (speed) and direction of an object's motion. It is calculated as the displacement traveled per unit of time.
Acceleration is a vector quantity that refers to the rate at which an object's velocity changes. It is calculated as the change in velocity per unit of time.
When you apply a constant force to the brake pedal, the car will slow down. This means that its velocity decreases, and consequently, its speed also decreases. Therefore, options c (Acceleration) and d (Speed andVelocity) are changing.
To further explain, when you apply the brakes, your car slows down and eventually comes to a stop. This change in motion is due to a negative acceleration, as the velocity is decreasing in the opposite direction of its initial motion. The consistent application of the brakes causes the velocity to decrease at a constant rate, resulting in a changing speed and velocity.
Therefore, the correct answer is:
d. Speed and Velocity