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A boy throws a ball of mass 0.25 kg straight upward with an initial speed of 20 m/s. When the ball returns to the boy, its speed is 17 m/s. How much work does air resistance do on the ball during its flight?

Respuesta :

Answer:

The work done is 13.875 J.

Explanation:

Given that,

Mass of ball = 0.25 kg

Initial speed = 20 m/s

Final speed = 17 m/s

We need to calculate the work done

Using formula of work done

Work done by the friction

[tex]W=\Delta K.E[/tex]

[tex]W=\dfrac{1}{2}m(v_{2}^{2}-v_{1}^{2})[/tex]

[tex]W=\dfrac{1}{2}\times0.25(17^2-20^2)[/tex]

[tex]W=−13.875\ J[/tex]

Negative sign shows the friction always against displacement.

Hence, The work done is 13.875 J.

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