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: heat
Insulation Traps Heat. Keeping the cold air out
Explanation:
Answer:
Though you have not gave the choices, I do believe it is “testing”
Explanation:
Answer:
The tension in the rope is 262.88 N
Explanation:
Given:
Weight
N
Length of rope
m
Initial speed of ball 
For finding the tension in the rope,
First find the mass of rod,
(
)

kg
Tension in the rope is,


N
Therefore, the tension in the rope is 262.88 N