A large electromagnet is used in a scrap yard to move old cars. a) Name a suitable material for the electromagnet. Explain your choice.

b) A car of mass 1800kg can be just be lifted. What is the least force that the electromagnet must use to lift the car? (1g=10 N/kg)​

Consider a production line with five stations. station 1 can produce a unit in 9 minutes. station 2 can produce a unit in 10 minutes. station 3 has two identical machines, each of which can process a unit in 12 minutes (each unit only needs to be processed on one of the two machines. station 4 can produce a unit in 5 minutes. station 5 can produce a unit in 8 minutes. which station is the bottleneck station?