A particle of mass m is projectile with veoocity u making an angle of `45^(@)` with the horizontal.When the particle lands on the level ground, the magnitude of the change in its momentum will be

Explanation

The situation is shown in figure.

Change in momentum,
`Deltap = p_(f) - p_(i) = m(v_(f)-v_(i))`
`=m[(v cos45^(@)i-vsin45^(@)j) -(vcos45^(@)i-v sin45^(@)j)]`
`Deltap = m[(v/sqrt(2)i-v/sqrt(2)j)]-(v/sqrt(2)i+v/sqrt(2)j)]`
`=-sqrt(2)mvj`
`therefore |Deltap| = sqrt(2)mv`
which is acting along (-)ve y-direction.