Kinematics — Identify the Scalar Quantity

Introduction / Context:
Physical quantities are classified as scalars (magnitude only) or vectors (magnitude and direction). Correctly identifying which is which is fundamental to solving mechanics problems correctly.

Given Data / Assumptions:

• Options include common motion-related quantities: force, speed, velocity, acceleration.
• Assume standard physics definitions in SI units.

Concept / Approach:
A scalar quantity is fully described by a number and appropriate unit, with no directional attribute. A vector quantity requires both magnitude and direction and follows vector addition rules.

Step-by-Step Solution:

Verification / Alternative check:
Speed is the magnitude of velocity. Magnitude alone is scalar; only when direction is attached (velocity) does it become a vector.

Why Other Options Are Wrong:
Force, velocity, and acceleration inherently require direction to be fully specified and obey vector laws (e.g., parallelogram rule). Hence they are vectors, not scalars.

Common Pitfalls:
Confusing speed with velocity; thinking that “fast” implies a direction; treating acceleration as “just speeding up” rather than a vector that can also indicate slowing or turning.

Final Answer:
Speed.