Question

A student is pushing a 35 kg desk across a floor at a constant speed of 4 m/s. How much work, to the nearest whole joule, must the student do on the desk to change the speed to 6 m/s?

Answer 1

Answer on Question #73127- Physics / Mechanics | Relativity

A student is pushing a $m = 35$ kg desk across a floor at a constant speed of $v_{1} = 4 \, \text{m/s}$. How much work, to the nearest whole joule, must the student do on the desk to change the speed to $v_{2} = 6 \, \text{m/s}$?

Solution:

Work done = change of energy

$$W = \frac{m v_{2}^{2}}{2} - \frac{m v_{1}^{2}}{2}$$ $$W = \frac{35 \times 36}{2} - \frac{35 \times 16}{2} = 630 - 280 = 350 \, \text{J}$$

Answer $W = 350 \, \text{J}$

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