Question

an object is Initially at a distance of 100cm from a plane mirror. If the mirror approaches the object at a speed of 5cm/s.Then after 6s the distance between the object and its image will be......
a. 60
b. 140
c. 170
d. 150​

Answer 1

Answer:

b. 140

Explanation:

The distance of object from plane mirror D=100cm

So, initial distance of image and object

=100−(−100)

=200cm

Now, object approaches the mirror with the speedv=5cm/s  

So, distance travelled by object in 6 sec

D=5×6

D=30cm

At this instant,

Distance between mirror and object

D=100−30

D=70cm

Now, the distance between image and object is

D=70−(−70)

D=140cm