Question

A man standing on the ground wants to climb the top of a vertical pole 13m tall. He climbs 5m in 1sec and then slips downwards, 3m in the next second. He again climbs 5m in 1sec and by 3m in the next second and so on. Draw the X-t graph of the motion of the man and hence find the time it will take the man to reach the top of the pole.

Answer 1

Given A man standing on the ground wants to climb the top of a vertical pole 13m tall. He climbs 5m in 1sec and then slips downwards, 3m in the next second. He again climbs 5m in 1sec and by 3m in the next second and so on.

Here the man climbs 5 m in one sec and comes down

3 m in next sec.

So the man climbs 2 m in 2 secs

So now the man climbs 10 m in 10 secs.

So for 11 th sec he climb the remaining 3 m so as to reach the pole.

hence it takes 11 secs for the man to climb the pole.

Answer 2

The man will take 9 seconds to reach the top of the pole

Explanation :

Given that the man climbs 5 m in one second and slips down 3 m in the next second

=> distance traveled in 2 sec = 5 - 3 = 2 m

similarly in the next cycle he will also climb a net height of 2 m

=> height traveled in 8 sec = 8 m

Next in the 9th sec he will again climb 5 meter

=> height at the end of 9th sec = 8 + 5 = 13 m

which is equal to the height of the pole,

Hence the man will take 9 seconds to reach the top of the pole