COMEDK2014PhysicsMotion in One Dimension
A car covers the first half distance between two places at 40 kmph and the other half at 60 kmph . The average speed of the car is
Options
- A48 kmph
- B120 kmph
- C50 kmph
- D24 kmph
Correct answer
A. 48 kmph
Step-by-step solution
The given situation is shown below Let the distance between the twro places is x ~km . A M=M B= x 2 ~km Time taken by the car to cover first half (A M) with the speed of 40 ~km / h is given as t₁= A M 40 = x / 2 40 = x 80 ~h Similarly, time taken by the car to cover second half (M B) with the speed of 60 ~km / h is given as t₂= M B 60 = x / 2 60 = x 120 ~h Average speed of car, aligned v_ avg &= Total distance travelled Total time taken &= x x 80 + x 120 = x 5 x 240 &= 240 5 =48 ~km / h aligned