Question

A 17 kg box experiences an applied force of +175 N and a force of friction of -125 N. While experiencing these unbalanced forces, the box travels a total of 15.0 meters in 5.25 seconds.
Calculate the power developed by the unbalanced forces to move the box.



A
44.1 watts
B
143 watts
C
263 watts
D
750 watts

Answer 1

Answer: (b)

Explanation:

Given

Mass of box $m=17\ kg$

Applied force $F=175\ N$

Friction force $f=-125\ N$

Box travels a distance of $s=15\ m$

time taken $t=5.25\ s$

Net unbalanced force $F_{net}=175-125=50\ N$

Work done by the unbalanced force

$\Rightarrow W=F_{un}\cdot s\\\Rightarrow W=50\times 15\\\Rightarrow W=750\ N$

Power developed by unbalanced force

$\Rightarrow P=\dfrac{W}{t}\\\\\Rightarrow P=\dfrac{750}{5.25}\\\\\Rightarrow P=142.85\approx 1423\ W$

Thus, option (b) is correct.