Question

An elevator descends into a mine shaft at the rate of $7$ m per minute. If the decent starts from $20$ m above the ground level, find the time taken by the elevator to reach $-400$m.

• A. $1$ min
• B. $1$ hr
• C. $1$ sec
• D. none

Answer 1

Answer: (B)

$1$ hr

$Distancetobecovered=400+20=420m\therefore timetaken=\left(\frac{420}{7}\right)min=60min=1Hr$