Question

A car travels a distance A to B at a speed of is $40\text{\hspace{0.17em}km/hr}$ and returns to A at a speed of $30\text{\hspace{0.17em}km/hr}$. The average velocity (in km/hr) for the whole journey is,

• A. $34.3$
• B. $0$
• C. $35$
• D. $36.3$

Answer 1

The correct option is B

$0$

Hint: Use formula $\text{Time}=\frac{\text{Distance}}{\text{Speed}}$

Concept Used: Time and Speed

Explanation:

Calculate average velocity.

Knows the car returns to the original position.

Total displacement is equal to zero.

Knows, $\text{Average\hspace{0.17em}speed}=\frac{\text{total\hspace{0.17em}distance\hspace{0.17em}travelled}}{\text{total\hspace{0.17em}time\hspace{0.17em}taken}}$

$\begin{array}{l}\text{Average velocity}=\frac{\text{total displacement}}{\text{time taken}}\\ =\frac{0}{2t}\\ =0\end{array}$

Hence, the average velocity (in km/hr) for the whole journey is $0$.