A car moves a distance of 200 m. It covers first half of the distance at speed 60 kmh-1 and the second half at speed v. If the average speed is 40 kmh-1, the value of v is

Question

A car moves a distance of 200 m. It covers first half of the distance at speed 60 kmh-1 and the second half at speed v. If the average speed is 40 kmh-1, the value of v is (A)  30 kmh-1  (B)  13 kmh-1  (C)  60 kmh-1  (D)  40 kmh-1

Tardigrade Admin · Accepted Answer

Average velocity =(2v1v2/v1+v2) Given vav=40 text kmh-1 v1=60 text kmh-1 and v2=? 40=(2× 60× v2/60+v2) v2=30 text kmh-2

Q. A car moves a distance of $200 m$ . It covers first half of the distance at speed $60 km h^{- 1}$ and the second half at speed $v$ . If the average speed is $40 km h^{- 1},$ the value of $v$ is

$30 km h^{- 1}$

$13 km h^{- 1}$

$60 km h^{- 1}$

$40 km h^{- 1}$

$20 km h^{- 1}$

Average velocity $= \frac{2 v _{1} v _{2}}{v _{1} + v _{2}}$
Given $v_{a v} = 40 km h^{- 1}$
$v_{1} = 60 km h^{- 1}$ and $v_{2} = ?$
$40 = \frac{2 \times 60 \times v _{2}}{60 + v _{2}}$
$v_{2} = 30 km h^{- 2}$

Q. A car moves a distance of 200m. It covers first half of the distance at speed 60kmh−1 and the second half at speed v. If the average speed is 40kmh−1, the value of v is

30kmh−1

13kmh−1

60kmh−1

40kmh−1

20kmh−1

Average velocity =v1​+v2​2v1​v2​​ Given vav​=40kmh−1 v1​=60kmh−1 and v2​=? 40=60+v2​2×60×v2​​ v2​=30kmh−2