Question

When the velocity of body is variable, then

• A. Its speed may be constant
• B. Its acceleration may be constant
• C. Its average acceleration may be constant
• D. All of these

Answer 1

Answer: (D)

If velocity is changing they may change in magnitude or direction or both.
(i) So, if velocity is changing in direction only the magnitude is constant so speed is constant.
(ii) If only direction of velocity is changing and magnitude is constant then acceleration will also be constant in magnitude (in case of uniform circular motion).
(iii) Average acceleration may be constant.
$a_{av}=\frac{v_2-v_1}{t_2-t_1}$