A body of mass 1 kg is projected from ground at an angle 30∘ with horizontal on a level ground at a speed 50 m/s. The magnitude of change in momentum of the body during its flight is (g=10 m/s2)
The correct option is A. 50 kg ms−1.
We know that in the horizontal plane, the initial velocity of projectile = final velocity of the projectile
→pi=mucosθ^i+musinθ^j
→pf=mucosθ^i−musinθ^j
Δ→p=→pf−→pi=−2musinθ^j
|Δ→p|=2musinθ
=2×1×50×12=50 kg ms−1
Alternative: In the horizontal direction momentum does not change,
Δ Px=0
In vertical direction
ΔPy=(musinθ)−(−musinθ) (Take downward as positive)
=2musinθ downward
=2×1×50×12=50 kg ms−1