Question

How much work is required to raise a 0.1 kg block to a height of 2 m and simultaneously give it a constant velocity of 3 m/s? b) What is the change in its potential energy? c) What is the power output of the upward force in watts?

Answer 1

(a)$W=mgh+\frac{1}{2}mv^2$

$=(0.1\times9.8\times2)+(\frac{1}{2}\times0.1\times3^2)$

$=2.41J$

(b) $\triangle P=P_2-P_1 \space$ but $P_1=0$

$\triangle P=mgh=0.1\times9.8 \times2=1.96J$

(c) $P=F\times V=0.1\times 9.8\times3=2.94W$