Question

A rocket is launched upward from the earth surface whose velocity-time graph shown in figure. Then maximum height attained by the rocket is
(1) 1 km
(2) 10 km
(3) 100 km
(4) 60 km

Answer 1

Answer: option (4) 60km

Step-by-step explanation:

   here graph is given,

maximum height is attained by rocket = area enclosed by part of graph which is above the x - axis.

              = area of triangle OAB

              = 1/2 * OB * altitude AT

 

             = 1/2 × 120 seconds × 1000 m/s

             

              = 60 × 1000 m = 60 km

hence, height attained by rocket is 60km

[ note : rocket starts from rest and moves upwards with increasing speed at 20sec , after 20sec rocket decreases its speed continuously, at point B e.g., t = 120 sec speed of rocket becomes zero. so, now rocket starts to fall downwards. but question asked we have to find maximum height attained by rocket , so just require to find the distance travelled by rocket unless it becomes rest in upward motion,e.g, t = 120sec . that’s why we find area enclosed by graph at point B. ]

Answer 2

Answer:

base :--20

height :-1km

area:-- 1/2× height ×base

area:- 1/2 ×20×1

area : 10km

10km is right answer.....