C) alternating current .
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B)direct current </span>
A. True.
You can make a hygrometer using strands of hair.
Answer: 6,400 km
Explanation:
The weight of a person is given by:

where m is the mass of the person and g is the acceleration due to gravity. While the mass does not depend on the height above the surface, the value of g does, following the formula:

where
G is the gravitational constant
M is the Earth's mass
r is the distance of the person from the Earth's center
The problem says that the person weighs 800 N at the Earth's surface, so when r=R (Earth's radius):
(1)
Now we want to find the height h above the surface at which the weight of the man is 200 N:
(2)
If we divide eq.(1) by eq.(2), we get


By solving the equation, we find:

which has two solutions:
--> negative solution, we can ignore it
--> this is our solution
Since the Earth's radius is
, the person should be at
above Earth's surface.
Answer:
Explanation:
There are three types of waves mainly.
1. Mechanical waves : Which needs a medium for there propagation. For example, sound waves
2. Non mechanical waves : Which do not need a medium or their propagation.
for example, light waves
3. Electromagnetic waves : Which are produced due to the interaction of electric and magnetic field. for example, X rays, light waves
The wave motion are of two types.
1. Transverse wave motion
2. Longitudinal wave motion
The kinetic energy increase because as temperature warms up particles move faster