An agitated protester lifts a stone of mass 200 g from the ground and throws it at an opponent. At the instant of projection, the stone is 150 cm above the ground and possesses a speed of 3.00 m/s . Determine the work done by the protester during this process. If the protester takes one second to lift and throw the stone, what horsepower is utilized?

Step-by-step solution

Mass of the stone, m = 200 g = 0.2 kg Height of projection, h = 150 cm = 1.5 m Speed of projection, v = 3.00 m/s Time taken, t = 1 s The work done by the protester is equal to the total mechanical energy imparted to the stone. W = K + U W = 1 2 mv^2 + mgh W = 1 2 (0.2)(3.00)^2 + (0.2)(9.8)(1.5) W = 0.9 + 2.94 = 3.84 J Power utilized is the work done per unit time. P = W t = 3.84 1 = 3.84 W Since 1 hp = 746 W , the power in horsepower is: P = 3.84 746 hp 5.14 10⁻³ hp