A boy throws a ball of mass 0.293 - kg straight upward with an initial speed of 23m/s. When the ball returns to the boy, its speed is 18.24 m/s. How much work does air resistance do on the ball during its flight?
The work done is equal to change in kinetic energy of the system
"W=\\frac{m v_2^2}{2}-\\frac{m v_1^2}{2}"
"W=\\frac{0.293*18.24^2}{2}-\\frac{0.293*23^2}{2}=-28.8\\:\\rm J"
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