Question

speed, velocity & acceleration
speed is the rate used to measure the distance traveled over a period of time.
speed = distance/
time
average speed =
total distance/total
time
velocity is a measure of the speed in a given direction.
question: a green helicopter is moving up at 30 kilometers per hour. a blue helicopter is moving down at 30 kilometers per hour.
a. are the helicopters speeds the same? explain
b. are the velocities the same? explain

• acceleration is the change of velocity over a period of time.
• if speed or direction changes, then you have acceleration.

Explanation:

• For part A: Speed is a scalar quantity (only magnitude). The green helicopter's speed is \(30\) km/h and the blue helicopter's speed is also \(30\) km/h. Since speed only cares about the magnitude of the rate of distance - covered over time, we compare just the numerical values.
• For part B: Velocity is a vector quantity (magnitude and direction). The green helicopter has a velocity of \(30\) km/h (upward direction) and the blue helicopter has a velocity of \(30\) km/h (downward direction). Since their directions are different, even though the magnitudes (speeds) are the same, vectors (velocities) are different.

Answer:

• A. Yes, the helicopters' speeds are the same. Speed is a scalar (only magnitude). Both have a magnitude of \(30\) km/h.
• B. No, the velocities are not the same. Velocity is a vector (magnitude and direction). The green helicopter moves up and the blue moves down (different directions).