Aparticularly scary roller coaster contains a loop-the-loop in which the car and rider are completely upside down. if the radius of the loop is 12.1 m with what minimum speed must the car traverse the loop so that the rider does not fall out while upside down at the top? assume the rider is not strapped to the car.

Explanation:

given,                          

radius of loop = 12.1 m                              

to find the minimum speed transverse by the rider to not to fall out upside down                                                                

centripetal force =

gravitational force  = m g

computing both the equation]

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.