Why is an iron core needed in an electromagnet?

An iron core is needed in an electromagnet because it  serves to increase the magnetic field created. It has a ferromagnetic properties. An electromagnet is essentially just a battery attached to a coil of wire wrapped around a metalcore. 

the best answer for these questions would be:

1.            c. is smaller

2.            d) concrete operational

3.            b) interaction with the environment – the children interact with their environment can them learn more.

4.            a) parents who reason openly with children can limit a child’s cognitive ability.

So since the snail is moving at 3.6  miles per hour you multiply by 5280 to change it into feet per hour. so you get 36*528 ft per hour. since there are 3600 seconds in an hour, you divide 36*528 by 3600. so simplifying we get 528/100 which is 5.28 ft per second