Question

Which of the following statements is false?
A.A body can have zero velocity and still be accelerated.
B.A body can have a constant velocity and still have a varying speed.
C.A body can have a constant speed and still have a varying velocity.
D.The direction of the velocity of a body can change when its acceleration is constant.

Answer 1

Hint: To solve this problem we will learn about the motion, speed, velocity and acceleration and the concept behind these terms and by using this information we can easily approach the correct answer for our question.

Complete answer:
Motion: Motion states that if it changes its position with respect to its surrounding with respect to time.
Speed: Speed is defined as the time rate of change of distance of a body also it is defined as the distance travelled by a body in unit time. Speed is a scalar quantity; it can be either positive or zero but never negative. Speed of a running car is measured by a speedometer. It is measured in $m/s$ .
$Speed = \dfrac{{Dis\tan ce\,\,travelled}}{{Time\,taken}}$

Velocity: Velocity is defined as the time rate of change of displacement of a body, also it is defined as the distance travelled by a body in unit time in a given direction. Velocity can be either $ + ve$, $0$ or $ - ve$ . It is measured in $m{s^{ - 1}}$.
$v = \dfrac{s}{t}$

Acceleration: Acceleration states that the time rate of change of its velocity. Acceleration is a vector quantity having both magnitude and the direction. It can be either $ + ve$ , $ - ve$ and $0$ . Acceleration is zero when it moves with uniform velocity. It is measured in $m{s^{ - 2}}$ .
$Acceleration\, = \dfrac{{v - u}}{t}$

Velocity consists of magnitude, with which a body is moving and its direction. Magnitude of velocity is called speed.
Therefore, it is not possible to have different speed and the same velocity.
So, the correct answer is option A - A body can have zero velocity and still be accelerated.

Note: Velocity is a vector quantity. When an object moves back and forth and always returns to its original position, it has speed but zero velocity because it doesn’t change position, if a man is jumping from one foot to the other as fast as he can but remains in one spot, he has speed but zero velocity.