InterviewSolution
Saved Bookmarks
| 1. |
Image of an object approaching a convex mirror of radius of curvature 20m slong its optical axis is observed to move from `(25)/(3)`m to `(50)/(7)`m in 30 seconds. What is the speed of the object in km per hour? |
|
Answer» Correct Answer - 3 `R=20 cm, f=10 m` For mirror, `(1)/(v)+(1)/(u)=(1)/(f)` `(1)/(25//3)+(1)/(u_(1))=(1)/(10)` `rArr u_(1)=-50 cm` `& (1)/(50//7)+(1)/(u_(2))=(1)/(10)` `rArr (1)/(u_(2))=(1)/(25) rArr u_(2)=-25 cm` So, speed `=|(Deltau)/(Deltat)|=(35)/(30) m//sec.=(5)/(6)m//sec` . `&` in `km//hr=(5)/(6)xx(18)/(5)=3 km//hr` . |
|