10

i think the answer should be 25 seconds. but the options don't have it.

Why do you think it should be 25 seconds? Show your work.

Look at it in terms of "5 steps forward and 3 steps back". That gains 5- 3= 2 m forward and take 5+ 3= 8 seconds.

For the first question, total distance covered = length of train + length of bridge.

 

 

For the second one, draw a displacement time graph.

Ah 11th std NCERT were the good times....Check your displacement again.

He takes 55 steps forward and 30 steps backwards

He takes 55 steps forward and 30 steps backwards

 

Its not possible. A pit at a distance of 11m. Each step of 1m. 55-30=25, which means 25m. The dude definitely missed the pit according to your calculations.

Why 25 and not 30?

 

Edited August 19, 20178 yr by rosadaniels

 First he goes forward to 5 m and then back to 2m.  That takes 8 seconds.  Then he goes forward to 7m and back to 4m.  That also takes 8 s so a total of 16 seconds.  Then he goes forward to 9m and back to 6 m.  That is now a total of 24 seconds.  Finally, he goes forward to 11m and falls into the hole.  That is a total of 29 seconds.

Edited August 19, 20178 yr by Country Boy