Which of the following is a vector quantity?

A. 100 ounces of water

B. 30 m down

C. 88 mi/s

D. 45 gallons in a bucket

B. 30 m down

Explanation:

In physics we have two types of quantities:

- Scalar quantity: it is a quantity which only has a magnitude (e. g: mass and time are scalar quantities, since they only have a magnitude)

- Vector quantity: it is a quantity which has both a magnitude and a direction (e. g: velocity is a vector quantity, since it has a magnitude (the speed) and a direction)

In this problem, we have:

A. 100 ounces of water - -> scalar (this is a volume, which has only a magnitude)

B. 30 m down - -> vector (this is a displacement, which has both a magnitude (30 m) and a direction (down)

C. 88 mi/s - -> scalar (this is a speed, which has only a magnitude)

D. 45 gallons in a bucket - -> scalar (this is a volume, which has only a magnitude)

So, the correct option is B.