Answer:
A Magnesia
Explanation:
The word magnetism comes from the word Magnesia, which is the name for a region in Asia Minor, where fragments of Fe3O4 ore (magnetite) were found, which attracts other metal objects.
Magnetism is a physical phenomenon by which we describe the attractive or repulsive force between materials.
This phenomenon has been known for thousands of years.
Answer:
lower
Explanation:
The lower the value of the coefficient of friction, the lower the resistance to sliding.
The coefficient of friction is the ratio of the frictional force and the normal force pressing two surfaces in contact together.
U =
U is the coefficient of friction
F is the frictional force
N is the normal force
We see that coefficient of friction is directly proportional to frictional force.
Answer:
Probability of tunneling is 
Solution:
As per the question:
Velocity of the tennis ball, v = 120 mph = 54 m/s
Mass of the tennis ball, m = 100 g = 0.1 kg
Thickness of the tennis ball, t = 2.0 mm = 
Max velocity of the tennis ball,
= 89 m/s
Now,
The maximum kinetic energy of the tennis ball is given by:

Kinetic energy of the tennis ball, KE' = 
Now, the distance the ball can penetrate to is given by:


Thus



Now,
We can calculate the tunneling probability as:



Taking log on both the sides:


Answer:
Its mechanical energy is the same.
Explanation:
If forces are only conservative, the mechanical energy will be the same.
It can be different if energy get transformed in another kind of energy like elastic energy for example, although the amount of energy is always the same.
If we just have mechanical energy not geting transformed we have:
Em=K+U
Em: Mechanical energy
K: Kinetic energý
U: Potential energy
Then if Kinetic energy decreases 10J, Potential energy will grow up 10J to keep the same amount of mechanical energy.
A protostar reaches equilibrium when gravity is balanced by the outward force of nuclear fusion.