Question

Read the passage given below carefully and answer the questions based on it:
Rohan and Anirban are students of the same school that is 18 km away from their hostel. One
day, they started from their hostel at the same time with an initial velocity of 28.8 km/hr. At
this speed, it would take 20 min for them to reach the school on time. After 5 min, Rohan
stopped due to some problem in his cycle. Anirban didn't wait for him and moved forward.
Rohan took another 5 min to repair his cycle. He again started with the same initial velocity
as he started from the hostel.
1. At what distance from their hostel did Rohan stop?
2. What is the required acceleration for Rohan to reach his school on time when he started the
second time?
3. What is the difference between distance travelled and displacement in reference to above
passage?
4. With what acceleration Anirban covers the distance from hostel to school?
5. What will be their final velocity once both will reach the school?
6. What will be the value of displacement covered by Anirban in going from hostel to school
and returning back to hostel after dispersal from school? Explain with reason.
7. With what acceleration Rohan was moving before the problem occurred in his cycle? What
do you observe after finding its value?

Answer 1

Explanation:

Distance from hostel to school = 18KM

Initial velocity = 28.8km/hr

i) Rohan had to stop after 5 mins from start time of journey.

Distance covered = velocity x time

Distance covered = 28.8 x (5/60) = 2.4 KM

ii) Remaining distance for Rohan = 18 - 2.4 = 15.6 KM

   Time left in journey = 10 mins

    Initial velocity = 28.8

To find acceleration,

s= ut + 1/2 at^2

15.6 =  (28.8) ( 1/6) + 1/2 a (1/6)^2

10.8 =  1/2 a (1/6)^2

Solving the equation;

a = 777 km/h

iii) DIstance is the lengh that Rohan will travel on cycle and displacement would be the net difference between starting and final positions