A boy drags a toy box 2.0 m along the floor by means of a force of 10 N directed downward at an angle of 60° to the horizontal to dissipate power of 6.7 W. For how long is the boy pushing the toy ?
Answer & explanation
Correct answer: option 3
\(\text{Work done } = \text{Force x Displacement x } \cos {\theta}\)
\(W = 10 \text{ N x } 2.0 \text{ m x } \cos {60^o} = 10 \text{ J}\)
\(\text{Power = } \frac{\text{Work Done}}{\text{Time}}\)
\(6.7 \text{ W} = \frac{10 \text{ J}}{t}\)
\(\Rightarrow t = 1.49 \text{ s} ≈ 1.5\text{ s} \)