InterviewSolution
Saved Bookmarks
InterviewSolution
| 1. |
Certain force acting on a 20 kg mass changes its velocity from `5m//s to 2m//s`. calculate the work done by the force. |
|
Answer» The work done by the force will be equal to the change in kinetic energy when the velocity changes from `5 m s^(-1)` to `2 m s^(-1)`. (i) In the first case : Mass, m = 20 kg And Velocity, `v = 5 m s^(-1)` `K.E. = (1)/(2) mv^(2)` `= (1)/(2) xx 20 xx (5)^(2)` `= (1)/(2) xx 20 xx 25` `= 250 J" "...(1)` (ii) In the second case : Mass, m = 20 kg And Velocity, `v = 2 m s^(-1)` So, `K.E. = (1)/(2) mv^(2)` `= (1)/(2) xx 20 xx (2)^(2)` `= (1)/(2) xx 20 xx 4` `= 40 J" "...(2)` Work done by force = Change in kinetic energy `= 250 - 40 J` = 210 J |
|