State whether the following statements are true or false:
$(a)$ An object can have acceleration even when its velocity is zero.
$(b)$ If the acceleration of a moving object is constant,the direction of its velocity must remain the same.
$(c)$ The speed of an object can never be zero.
$(a)$ An object can have acceleration even when its velocity is zero.
$(b)$ If the acceleration of a moving object is constant,the direction of its velocity must remain the same.
$(c)$ The speed of an object can never be zero.
(A) True. For example,at the highest point of a vertically thrown object,the velocity is zero,but the acceleration due to gravity $(g = 9.8 \ m/s^2)$ is still acting on it.
$(b)$ False. An object can have constant acceleration while changing direction,such as in uniform circular motion or when an object is thrown at an angle (projectile motion).
$(c)$ False. The speed of a stationary object is zero.
$(b)$ False. An object can have constant acceleration while changing direction,such as in uniform circular motion or when an object is thrown at an angle (projectile motion).
$(c)$ False. The speed of a stationary object is zero.
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View SolutionFor the velocity-time graph shown in the figure,in a time interval from $t=0$ to $t=6\,s$,match the following columns.
Column $I$ Column $II$ $(A)$ Change in velocity $(p)$ $-5/3\,SI \text{ unit}$ $(B)$ Average acceleration $(q)$ $-20\,SI \text{ unit}$ $(C)$ Total displacement $(r)$ $-10\,SI \text{ unit}$ $(D)$ Acceleration at $t=3\,s$ $(s)$ $-5\,SI \text{ unit}$
| Column $I$ | Column $II$ |
|---|---|
| $(A)$ Change in velocity | $(p)$ $-5/3\,SI \text{ unit}$ |
| $(B)$ Average acceleration | $(q)$ $-20\,SI \text{ unit}$ |
| $(C)$ Total displacement | $(r)$ $-10\,SI \text{ unit}$ |
| $(D)$ Acceleration at $t=3\,s$ | $(s)$ $-5\,SI \text{ unit}$ |
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View SolutionWhich one of the following statements is wrong?
$A$ horse rider covers half the distance with $5\,m/s$ speed. The remaining part of the distance was travelled with speed $10\,m/s$ for half the time and with speed $15\,m/s$ for the other half of the time. The mean speed of the rider averaged over the whole time of motion is $\frac{x}{7}\,m/s$. The value of $x$ is
DifficultJEE MAIN 2023
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