Question

two balls of equal masses are projected upward simultaneously from the ground with speed 50 metres per second and the other from 40 metre high tower with initial speed 30 metre per second find the maximum height attained by the centre of mass

Answer 1

Answer:

The answer will be 100m

Explanation:

According to the problem one ball is projected with speed of 50 m/s

and another is projected from a height of 40 m with the speed of 30 m/s

Therefore the initial velocity of the center of mass be u

let the mass of two balls are m

therefore u = m x 50 +m x 30 /2m = 40 m/s

The position of center of mass at initial time= d

d= mx 0 +m x 40 /2m = 20 m

Let the acceleration  be a = -g

Therefore from the equation of kinetic energy we can say that

v^2 = u^2 +2ah

here h is the height achieved by the center of mass of the balls

0 = 40^2 - 2 x 10 x h

=>h = 80

Therefore the maximum height attained by the center of mass will be

d+h = 20+80 = 100 m