Q.

An object of mass m is projected with a momentum p at an angle θ with the horizontal such that its maximum height (H) is half of its Range (R). Minimum kinetic energy of the particle in its path will be

1 p28m  
2 3p24m  
3 p210m  
4 p25m  

Ans.

(3)

1×12g(psinθm)2=psinθmg×pcosθm

12sin2θ=sinθcosθ⇒tanθ=2

∴  cosθ=15

Minimum kinetic energy=(pcosθ2m)2=p22m×15=p210m