Question

A person was standing at a distance of 70m from a plane mirror. At what speed he should move
towards the mirror so that in 5 seconds his distance will become 20m from his own image?

Answer 1

Answer:

12m/s

Explanation:

initial distance =70m

the distance after running = 20/2

=10m

the time in which he should run =5 sec

speed = distance covered /time

=60/5 = 12m/s

Answer 2

A person was standing at a distance of 70m from a plane...

• Distance from image = 70*2=140m
• Distance to be travelled=140-20=120m
• Speed = Distance divided by time
• d/t =s
• But in this context:
• It is 2s is the total speed accumulated because the image also moves closer to the person at the same speed as he moves towards it.
• s= speed of the person
• 120m/5=2s
• 120/10=12
• 12 m/s is the answer