If you are under a tree, they kind of act like lightning rods, so stay away from trees, so roll in dat grass. Fun Fact: Lightning comes from the ground more than it comes from the sky, its like when you rub a blanket on your head, some lil' lightnings come from your head while a little come from the blanket, its the same with grass and clouds only, 10000 volts stronger and deadly.
Work = (force) x (distance)
80 J = (force) x (4 m)
Force = (80 J) / (4 m) = 20 N
That's IF the force was in the same direction as the 4m of motion.
If the force was kind of slanted, then it had to be stronger, and
it had a component of 20N in the direction of the motion.