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 at a relative speed of 15 m/sec. The speed of the image of the second car as seen in the mirror of the first one is:
(a) 1/1- m/sec
(b) 1/15 m/sec
(c) 10 m/sec
(d) 15 m/sec
Answers
Answered by
68
b) 1/15 m/s
Focal length = f = 20 cm = 0.2 m
Distance of second car = u = -2.8m relative speed of 2nd car=v=15m/s
Relative speed of image of 2nd car=v'
m= f/(f-u) = 0.2/0.2-(-2.8) =0.2/3 = 1/ 15
v'/v = m^2
》v'/15= (1/15)^2 =1/225
》v' = 15 × 1/225 = 1/15 m/ s
Focal length = f = 20 cm = 0.2 m
Distance of second car = u = -2.8m relative speed of 2nd car=v=15m/s
Relative speed of image of 2nd car=v'
m= f/(f-u) = 0.2/0.2-(-2.8) =0.2/3 = 1/ 15
v'/v = m^2
》v'/15= (1/15)^2 =1/225
》v' = 15 × 1/225 = 1/15 m/ s
Answered by
8
Answer:
1/15 is the answer
hope it helps
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