Answer
Josie and Charlotte pushed the bag with a force of $0.12~N$
Work Step by Step
We can find the kinetic energy of the bag:
$KE = \frac{1}{2}mv^2$
$KE = \frac{1}{2}(12~kg)(0.40~m/s)^2$
$KE = 0.96~J$
The work that they did on the bag is equal to the bag's change in kinetic energy. Since the bag started at rest, the change in the bag's kinetic energy is $0.96~J$.
We can find the force they used to push the bag:
$Work = F~d$
$F = \frac{Work}{d}$
$F = \frac{0.96~J}{8.0~m}$
$F = 0.12~N$
Josie and Charlotte pushed the bag with a force of $0.12~N$
