When a plane minor is placed horizontally on level ground at a distance of om from the foot of tower the top of the tower and its image in the mirror subtend an angle of 90" at the eye. The height of the tower
a) 30m
b) 60m
c) 90 m
d) 120m

b : 60m

Explanation:

when a plane mirror is placed horizontally on a level ground at a distance of 60m from the top of tower as shown in figure. a/c to question, The top of tower and its image in the mirror subtend an angle of 90° at the eyes. so, angle made by top of tower and horizontal line is 45° as

acceleration = (change in speed) / (time for the change)

change in speed = (20-120)= -100 m/s.

1.5 min = 90 sec

acceleration = -100/90 = -1.11 m/s^2.

we don't care about the 150kg or the 2,500 meters. they don't make any difference.

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