Question

A a multi-storey building has 25 floors above the ground level each of the height 5 metre. It also has 3 floors in the basement each of height 5 metre. A lift in the building moves at the rate of 3 metre per second if a man starts from 50 metre above the ground. Find time required to reach 2nd floor of the basement

Answer 1

A man starts from 50 m above the ground and he has to reach 2nd floor of the basement.
Height of each floor = 5 m

Distance traveled above basement =50 m

And below basement $=2\times 5=10$ m

$\therefore$ Distance to be covered $=50+2\times 5m$
$=60m$
Speed of the lift = 3 m/s
$\therefore$ Time required to reach 2nd floor of the basement $=3\times 60seconds$
$=3min$

Now we know the formula of speed,

Speed $=\frac{distance}{time}$

$\Rightarrow 3=\frac{60}{x}$ $\frac{m}{m/s}$

$\Rightarrow x=\frac{60}{3}$ $\frac{1}{/s}$

$\Rightarrow 20s$

Hence, a man reaches at 2nd floor of basement in 20 seconds.