The main advantage of an electromagnet over a permanent magnet is that the magnetic field can be quickly changed by controlling the amount of electric current in the winding. However, unlike a permanent magnet that needs no power, an electromagnet requires a continuous supply of current to maintain the magnetic field.
Answer:
4.25 m/s
Explanation:
They walked the first distance at 5.50 m/s, then the same distance at 3 m/s.
Since the distances are equal, the average speed is simply the average of 5.50 and 3.
(5.50 + 3) / 2 = 4.25
Her average speed over the entire trip is 4.25 m/s.
4:chemical properties can only be observed when a substance changes into another substance.
5: physical properties such as color and shape are easy to observe
6: in a chemical change an altered substance forms
7: cooking or baking food will result in a chemical change
8: a melting ice cube is a physical change
9: the rusting of iron is a chemical change
10: water boiling is a scientific physical change
