If a body moves with a constant speed and at the same time undergoes an acceleration, its motion is said to be

Step 1: Analyze the question The body has a constant speed but is also accelerating. We need to find the type of motion where both are true at once.

Step 2: Explain the concept

• Speed is a scalar (magnitude only). Velocity is a vector (magnitude and direction).
• Acceleration is the rate of change of velocity. So acceleration can happen when the speed changes, when the direction changes, or both.
• If the speed is constant but the body accelerates, the direction must be changing continuously.

Step 3: Check the options

• A. Oscillation: In oscillation (like a pendulum or a spring), the speed keeps changing. It is zero at the extremes and maximum at the centre. So the speed is not constant.
• B. Circular: In uniform circular motion, the speed is constant, but the direction of velocity changes continuously. This gives a centripetal acceleration of a = v²/r directed toward the centre. This fits both conditions.
• C. Rotational: This describes a body spinning about an axis. It is not specifically the motion of a body at constant speed with acceleration, and the term is too general (a rotating body can speed up or slow down).
• D. Rectilinear: Motion in a straight line. If the speed is constant, the velocity is constant, so the acceleration is zero. This contradicts the question.

Step 4: Answer The motion is circular (uniform circular motion), which is option B.

Tip: Whenever you see "constant speed but accelerating", think circular motion. The speed stays the same, but the changing direction means the velocity changes, and so there is acceleration (centripetal acceleration). Remember: constant speed ≠ constant velocity.