Bill is throwing a football at four targets and attempting to knock them over. which of the following targets will be hardest for him to knock over? a. the 100-gram lead target b. the 50-gram plastic target c. the 150-gram nylon target d. the 25-gram silicone target

force is mass*acceleration.

we have a very small mass: 11.4*0.001 kg

if we want 0.035n of force, we need an acceleration:

0.035 = 11.4*0.001*a

a = 0.035/(11.4*0.001) m/s^2

the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.