Which of the following quantities is a vector?

Step 1: Analyze the question We are asked to identify which quantity is a vector. A vector has both magnitude and direction. A scalar has magnitude only.

Step 2: The concept

• Scalar quantities: mass, volume, energy, speed, distance, time, temperature, work, power
• Vector quantities: displacement, velocity, acceleration, force, momentum, weight, impulse

Step 3: Check each option

• A. Volume: This is the amount of space an object occupies. It has size only, with no direction. It is a scalar.
• B. Momentum: Momentum = mass × velocity (p = mv). Since velocity is a vector and mass is a scalar, momentum has direction (the same direction as the velocity). It is a vector.
• C. Energy: Energy is measured in joules and has no direction. It is a scalar.
• D. Speed: Speed is distance ÷ time, which gives only magnitude. (Velocity is the vector version.) It is a scalar.

Step 4: Answer Only momentum has both magnitude and direction, so the correct option is B. Momentum.

Exam tip: Whenever you see a quantity that contains velocity, displacement, or acceleration in its formula (like momentum = mass × velocity, or force = mass × acceleration), it is likely a vector. A simple memory trick: "Speed is scalar, velocity is vector." Also remember that energy, work, and power are scalars even though they involve force and distance.