Question

An object covers half its journey with a speed of 40m/s and the other half with a speed of 60m/s. Find its average speed for the whole journey.

Answer 1

Let the total distance it covers be $2x$

Time taken to cover the first half $t_1=\frac{x}{40}$

Time taken to cover the next half $t_2=\frac{x}{60}$

Total time taken = $t_1+t_2$

= $\frac{x}{40}+\frac{x}{60}$

= $\frac{100x}{2400}$

= $\frac{x}{24}$

Average speed = $\frac{totaldistance}{totaltimetaken}$

= $\frac{2x}{\frac{x}{24}}$

= $\frac{48x}{x}m/s$

= $48m/s$