Question

A car travels half of the distance with constant velocity 40 km/h and another half with a constant velocity of 60 km/h along a straight line. The average velocity of the car is

• A. 24 km/h
• B. 48 km/h
• C. 60 km/h
• D. 40 km/h

Answer 1

The correct option is B 48 km/h

Suppose total distance is $2x$ $km$ then

time taken in traveling the distance first $x$ will be $t_1=\frac{x}{40}$

and the time taken in traveling the distance second $x$ will be $t_2=\frac{x}{60}$

now the average velocity can be calculated as $V=\frac{\text{total distance}}{\text{total time}}=\frac{2x}{\frac{x}{40}+\frac{x}{60}}=\frac{2\times 40\times 60}{40+60}=48Km/h$