JEE Main 26-Aug-2021 Shift 1 Solved Paper

According to the question,
Velocity of car B w.r.t. mirror of car A,vBM=40m∕s
Distance of car B from mirror of car A,u=1.9m=190‌cm
Focal length of mirror, f = 10 cm
We have to find the velocity of image of car B in the mirror, i.e. vIM
We know that,
vIM=−m2vBM ....(I)
where, m is the magnification produced by mirror of car A,
⇒m=

f

f−u

=

10

10−(−190)

=

10

200

=

1

20

Substituting the values in Eq. (i), we get
vIM=−(

1

20

)2×40
=−

1

400

×40=−0.1m∕s
Here, negative sign shows that, the speed of image w.r.t. mirror ofcar A is in opposite direction.