Question

For which of the following is the velocity constant (speed/direction does not change)?
A) A cat escaping a dog by running in a straight line and then up a tree at a constant speed of 30 mph
B) A cat escaping a dog by running in a straight line away from the dog and slowing down when danger is gone.
C) A cat escaping a dog by running at a constant speed around and around the house until the dog gets bored.
D) A cat ignoring the dog by sitting perfectly still.

Answer 1

The answer is D. Velocity has a direction and a magnitude, so to have a constant velocity, none of them should be changing. A seems right at first, but when the cat climbs up a tree, it's changing directions. B says the cat slows down which means there's a change in velocity and acceleration is present. C says that the cat's running around in circles so it's constantly changing directions. D is the only right one because the magnitude of velocity (speed) is 0 and not changing neither is the direction. 

Hope this makes sense!