Q.)The resistance of a packing material to a sharp object is given by: $$F = 1.20 × 10^4 x^2$$ where x is the penetration depth. How much work has to be done to force a sharp object a distance 5.00 mm into the material?
I get the fact that you have to use the work formula $$W=\int_i^f\vec{F}*\vec{dl}$$ and then you have to change from vectors to just plain numbers, so for this case its this multiplied by cos(0) or 1 which doesnt really matter for this problem. So when I did this problem my final answer ends up as $$30x^4$$ and x is replaced by 0.005 since im looking for the joules and I seem to end up with $$1.875*10^{-8}$$ so when I looked over the several possible answers for this question being $$(A.) 1.88 × 10^{−6}J (B.) 60 J (C.) 1.50 × 10^{−3} J (D.) 7.50 × 10^{−6} J$$ Am I missing some steps or did I messed up along the way?