AIPMT 2008 Physics and Chemistry Paper

Only vertical component of velocity changes during projectile motion so, there is change in momentum in vertical direction only.Change in momentum =∆

→

P

=∆Px

⋀

i

+∆Py

⋀

j

, since ∆Px=0
=∆Py

⋀

j

=

→

P

fy−

→

P

iy
Piy=mv‌sin‌45∘,Pfy=−mv‌sin‌45∘
∆

→

P

=−mv‌sin‌45∘,−mv‌sin‌45∘
=−2mvsin45°=−√2mvj|Δ

→

P

|
=√2mv
−ve‌sign shows the direction of change in momentum in -ve y-direction.