A boy goes to school from his home at a speed of x km - hour and comes back at a speed of y km - hour then the average speed is given byA- A-M-B- G-M-C- H-M-D- None of these

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Direction of Instantaneous Velocity

A boy goes to...

Question

A boy goes to school from his home at a speed of x $\frac{k m}{h o u r}$ and comes back at a speed of y $\frac{k m}{h o u r}$ then the average speed is given by

A.M.

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G.M.

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H.M.

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None of these

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Solution

The correct option is C H.M.
Let, the distance of school from home = d
and time taken are $t_{1}$ and $t_{2}$ .
$∴ t_{1} = \frac{d}{x} a n d t_{2} = \frac{d}{y}$
Avg.velocity = $\frac{T o t a l d i s t a n c e}{T o t a l t i m e}$
$= \frac{2 d}{(\frac{d}{x} + \frac{d}{y})} = \frac{2 x y}{x + y},$ which is the H.M. of x and y.

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A boy goes to school from his home at a speed of x kmhour and comes back at a speed of y kmhour then the average speed is given by

The correct option is C H.M.Let, the distance of school from home = d and time taken are t1 and t2. ∴t1=dxandt2=dy Avg.velocity = Total distanceTotal time =2d(dx+dy)=2xyx+y, which is the H.M. of x and y.

A boy goes to school from his home at a speed of x $\frac{k m}{h o u r}$ and comes back at a speed of y $\frac{k m}{h o u r}$ then the average speed is given by