Question

An insect crawling up a wall crawls 5 cm upwards
in the first minute but then slides 3 cm downwards
in the next minute. It again crawls up 5 cm upwards
in the third minute but again slides 3 cm
downwards in the fourth minute. How long will
the insect take to reach a crevice in the wall at a
height of 24 cm from its starting point? How does
the position-time graph of the insect look like?
(Ans, 21 min​

Answer 1

Dear student,

● Answer -

Time taken to reach top = 21 min

◆ Explanation -

In every two minutes, the insect climbs 5 cm & slides 3 cm. So total progress in per two minutes is 5-3 = 2 cm.

In first 20 min, the insect will climb up 20/2 × 2 = 20 cm.

In 21st minute, the insect will climb 5 cm, making total climbing 20+5 = 25 cm.

Therefore, the insect will climb up wall of 25 cm in 21 minutes.

Keep asking...

Answer 2

Answer:

IN EVERY 2MIN., THE INSECT CLIMBS 5CM AND SLIDES 3CM, SO TOTAL PROGRESS IN PER 2MIN IS

5–3=2CM

IN FIRST 20MIN, THE INSECT WILL CLIMB UP

20/2×2=20CM

IN 21ST MIN, THE INSECT WILL CLIMB 5CM, MAKING

20+5=25CM

THEREFORE THE INSECT WILL CLIMB 25CM IN 21MIN