Question

a body of mass m is projected with initial speed u at angle theta with the horizontal.the change in momentum of body after time t is

Answer 1

As we know that a projectile action is a combination to horizontal and vertical movement. The vertical part of initial velocity ‘ u ’ always remains steady ,i.e. in this case , u x= u cos o , throughout the motion. So alter in momentum in horizontal direction is zero

Now analyzing the vertical movement we know initial velocity in vertical course u y = u sin o.

After time t , v y = u sin o – g t , ( equation of motion i.e v = u + a t )

Thus, Change in momentum in vertical track = m . v y – m . u y 

= m . ( u sin o – g t ) - ( m . u sin o )

= - m g t

 

Answer 2

Answer:

F=dp/dt

Fdt=dp

Integrate

F= mg

Mgt = change in momentum