A car moves a distance of 200 m . It covers first half of distance at speed 40 km / h and second hal

English

Gujarati

Hindi

2.Motion in Straight Line

medium

A car moves a distance of $200 \;m$. It covers the first half of the distance at speed $40 \;km / h$ and the second half of distance at speed $v$. The average speed is $48\; km / h$. The value of $v$ is

A

$56$

B

$60$

C

$50$

D

$48$

(AIPMT-1991)

Solution

Total distance travelled $=200 m$

Total time taken $=\frac{100}{40}+\frac{100}{v}$

Average speed $=\frac{\text { total distance travelled }}{\text { total time taken }}$

$48=\frac{200}{\left(\frac{100}{40}+\frac{100}{v}\right)}$

$48=\frac{2}{\left(\frac{1}{40}+\frac{1}{v}\right)}$

$\frac{1}{40}+\frac{1}{v}=\frac{1}{24}$

$\frac{1}{v}=\frac{1}{24}-\frac{1}{40}=\frac{5-3}{120}=\frac{1}{60}$

$v=60 km / hr$

Standard 11

Physics

Share

Similar Questions

A car travels half the distance with constant velocity of $40\, kmph$ and the remaining half with a constant velocity of $60 \,kmph$. The average velocity of the car in $kmph$ is

medium

(AIPMT-1990)

Figure gives a speed-time graph of a particle in motion along a constant direction. Three equal intervals of time are shown. In which interval is the average acceleration greatest in magnitude ? In which interval is the average speed greatest ? Choosing the positive direction as the constant direction of motion, give the signs of $v$ and $a$ in the three intervals. What are the accelerations at the points $A, B, C$ and $D$?

medium

Velocity of an object in rectilinear motion is given as function of time by $v = t -t^3$, where $v$ is in $m/s$ and $t$ is in seconds. Its average velocity over the time interval from $t = 0\ s$ to $t = 2\ s$ is……..$m/s$

hard

A vehicle travels $4\,km$ with speed of $3\,km / h$ and another $4\,km$ with speed of $5\,km / h$, then its average speed is $……….km/h$

medium

(JEE MAIN-2023)

A car goes from $A$ to $B$ (without changing direction), during first part of journey its average speed is $V_1$ and for second part of journey average speed is $V_2$ . The ratio path length of second part to the path length of first part is $\sqrt {\frac{{{V_2}}}{{{V_1}}}} $ . In that case the average speed of total path is ……. of average speeds of both parts. Choose correct option of fill.

hard