NTA Abhyas JEE Main2020PhysicsMotion in Two DimensionsPractice
A projectile of mass m is fired from ground with speed u at an angle θ to horizontal. What is the power of gravitational force, when it makes an angle θ 2 with the horizontal?
Options
- A- m g u   cos θ   tan θ 2
- B- m g u   tan θ   cos θ 2
- C- 2 m g u   tan θ   sin θ 2
- D- 2 m g u   sin θ   tan θ 2
Correct answer
A. - m g u   cos θ   tan θ 2
Step-by-step solution
v x = u cos ⁡ θ = v cos ⁡ θ 2 , where v is the speed at this instant v y = v sin θ 2 = u cos θ   sin θ 2 cos θ 2 = u cos θ   tan θ 2 P = F → . v → = - m g u   cos θ   tan θ 2