Question

A body cannot have a
A) zero speed and non-zero acceleration
B) non-zero speed and zero acceleration
C) constant velocity and a varying speed
D) constant speed and a varying velocity

Answer 1

Hint: The velocity of an object is often changed by: Change of speed, Change of direction And in a uniform circular motion, the direction is not always the same, rather, it keeps changing. While the speed can remain the same.

Complete answer:
Speed of the body is the magnitude of velocity. So, if velocity is simply changing direction then speed is constant. But if speed is changing then velocity got to be varying. When a body moves the instant when t=0 then it has zero velocity but some acceleration is there. Objects moving with constant velocity have zero acceleration but non zero speed.

So, the correct answer is “Option C”.

Additional Information:
Speed is directly proportional to distance when time is constant: \[v\propto s\](t constant)
Speed is inversely proportional to time when distance is constant: \[v\propto \dfrac{1}{t}\](s constant)
Speed and velocity are both measured using an equivalent unit. The SI unit of distance and displacement is that the meter. The SI unit of your time is that the second. The SI unit of speed and velocity is that the ratio of two — the meter per second.

Note:
In conclusion, speed and velocity are kinematic quantities that have distinctly different definitions. Speed, being a scalar quantity, is that the rate at which an object covers distance. The typical speed is the distance (a scalar quantity) per time ratio. Speed is unaware of direction. On the opposite hand, velocity may be a vector quantity; it's direction-aware. Velocity is the rate at which the position changes. The typical velocity is the displacement or position change (a vector quantity) per time ratio.