A student made the electromagnet shown and used it to pick up one sewing pin. Which change to the electromagnet would most likely allow it to pick up
two sewing pins?
A. Replace the nail with a thick roll of paper.
B. Double the length of the wires that connect it to the battery
C. Double the number of coils of wire around the nail.
D. Replace the nail with a large steel bolt.

Consider two less-than-desirable options. in the first you are driving 30 mph and crash head-on into an identical car also going 30 mph. in the second option you are driving 30 mph and crash head-on into a stationary brick wall. in neither case does your car bounce off the thing it hits, and the collision time is the same in both cases. which of these two situations would result in the greatest impact force?