Saved Bookmarks
| 1. |
A car is fitted with a convex side - view mirror of focal length 20 cm. A second car 2.8 m behind the first car is overtaking the first car at relative speed of 15 m/s. The speed of the image of the second car as seen in the mirror of the first one is : |
|
Answer» `(1)/(15)m//s` `-(1)/(v^(2))(DV)/(DT)-(1)/(u^(2))(du)/(dt)=0` `rArr(dv)/(dt)=(v^(2))/(u^(2))((du)/(dt))` f = 20 cm `(1)/(v) + (1)/(-280) = (1)/(20) rArrv = (280)/(15)cm` `THEREFORE (dv)/(dt)=-((280)/(15xx280))^(2)xx15=(1)/(15)ms^(-1).` |
|