Q. A body of mass 2 kg is projected at 20$ms^{- 1}$ at an angle $60{^\circ}$ above the horizontal. Power Due to the gravitational force at its heights point is
A) 200 W
B) 100$\sqrt{3}W$
C) 50 W
D) Zero
Explanation
(a) Given, m=2kg, v=20$ms^{- 1},$ $\theta = 60{^\circ}$
Power(P)is given as
$P = F \bullet v = Fv\cos\theta$
$P = mgv\ \cos\theta$
$\therefore\ \ P = 2 \times 20 \times 10 \times \cos{60{^\circ}}$
$P = 2 \times 20 \times 10 \times \frac{1}{2}$
$\Rightarrow \ \ \ \ P = 200\ W$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.