Question

A cricket ball of mass 150 g has initial velocity u=(3i+4j)m/s and final velocity v=-(3i+4j)m/s after being hit what is the change in momentum

Answer 1

asked Feb 27 in Class XI Physics by nikita74 (-1,051 points)
A cricket ball of mass 150 g has an initial velocity u = (3Î + 4ĵ ) ms-1 and a final velocity v = - (3Î + 4ĵ) ms-1 after being hit. The change in momentum (final momentum - initial momentum) is (in kg. ms-1).
(a) zero
(b) -(0.45Î + 0.6ĵ)
(c) -(0.9ĵ + 1.2ĵ )
(d) -5(Î + ĵ)

takes place always in the direction of the force applied.
We know that F = df/ dt
According to the question that the meter scale is moving with uniform velocity, hence, change in momentum will be zero, i.e. dp = 0
This implies momentum will remains same. So, Force = F= 0.
So, we can say that all parts of the meter scale is moving with uniform velocity because total force is zero and if there is any torque acting on the body this means that the body will be in rotational motion which means that the direction of velocity will be changing continuously. So, the torque acting about centre of mass of the scale is also zero.

Answer 2

The answer is in the image