a car that is traveling west at a constant rate has
A. speed, but neither velocity nor acceleration
B. speed and velocity but no acceleration
C. velocity but neither acceleration nor speed
D. acceleration and speed but no velocity
D. acceleration and speed but no velocity
The correct answer is B. speed and velocity but no acceleration.
Explanation:
Speed is defined as the magnitude of how fast an object is moving, regardless of its direction. In this case, the car traveling west has a constant rate, which means it has a constant speed.
Velocity, on the other hand, is a vector quantity, which means it includes both the magnitude (speed) and the direction of an object's motion. Since the car is traveling west, it has a velocity in the westward direction.
Acceleration is the rate of change of velocity. If the car is traveling at a constant speed and in a straight line without changing its velocity, then there is no acceleration. Therefore, the car has speed and velocity but no acceleration, making answer choice B correct.
The correct answer is A. speed, but neither velocity nor acceleration.
To understand why, let's first clarify the definitions of these terms:
1. Speed: Speed is a scalar quantity that refers to the rate at which an object moves. It is the magnitude of the velocity vector. Speed does not involve direction, only a numerical value.
2. Velocity: Velocity is a vector quantity that refers to the rate at which an object changes its position. Velocity involves both speed and direction. It is defined as the rate of change of displacement over time.
3. Acceleration: Acceleration is a vector quantity that refers to the rate at which an object changes its velocity. It involves both the change in speed and the change in direction. Acceleration is defined as the rate of change of velocity over time.
Now, let's apply these definitions to the scenario of a car traveling west at a constant rate:
Since the car is traveling at a constant rate, it means that its speed remains the same. The car's speed is always positive because it is moving.
However, since the car is traveling west (which implies a direction), it has a velocity. Velocity includes both speed and direction, and in this case, the car's velocity would have a magnitude equal to its speed and a direction of west.
On the other hand, since the car is moving at a constant rate, it is not experiencing any change in its velocity over time. Therefore, it has no acceleration. Acceleration involves the change in velocity, and if the car's velocity remains constant, then the acceleration is zero.
Hence, the car that is traveling west at a constant rate has speed but neither velocity nor acceleration, which corresponds to option A.