A car travels first half of a distance between two places at a speed of 30, km/hr and second half of

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2.Motion in Straight Line

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A car travels the first half of a distance between two places at a speed of $30\, km/hr$ and the second half of the distance at $50 \,km/hr$. The average speed of the car for the whole journey is..........$km/hr$

A

$42.5 $

B

$40.0$

C

$37.5 $

D

$35.0$

Solution

(c)Distance average speed$ = \frac{{2{v_1}{v_2}}}{{{v_1} + {v_2}}}$$ = \frac{{2 \times 30 \times 50}}{{30 + 50}}$
$ = \frac{{75}}{2} = 37.5\;km/hr$

Standard 11

Physics

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