A multistorey building has 25 floors above the ground level each of height 5m. It also has 3 floors in the basement each of height 5m. A lift in building moves at a rate of 1m/s. If a man starts from 50m above the ground, how long will it take him to reach at 2nd floor of basement?

We have

Since, it is given that the man starts from 50 m from the ground.

⇒ Distance of the man from the ground = 50 m

There are about 3 floors in the basement.

The man has to reach the 2^nd floor of the basement and it is given that, distance between floors is 5 m.

So, distance between ground and 1^st floor of basement = 5 m

And distance between 1^st floor and 2^nd floor of basement = 5 m

⇒ Distance between ground and 2^nd floor of basement = 5 + 5

⇒ Distance between ground and 2^nd floor of basement = 10 m

Total distance between man and 2^nd floor of the basement is given by,

Total distance = Distance between man and ground + Distance between ground and 2^nd floor basement

⇒ Total distance = 50 + 10

⇒ Total distance = 60 m

But, the speed of lift = 1 m/s

We need to find the time taken by the lift to reach 60 m at speed, 1 m/s.

Since,

⇒

⇒

⇒ Time = 60 s

Thus, it takes 60 seconds or 1 minute to reach at 2^nd floor of the basement.