The earth’s radius is 6.37 × 10 6 m ; it rotates once every 24 hours. what is the earth’s angular speed? viewed from a point above the north pole, is the angular velocity positive or negative? what is the speed of a point on the equator? what is the speed of a point on the earth’s surface halfway between the equator and the pole? (hint: what is the radius of the circle in which the point moves? )

a) the angular speed of the Earth's rotation is 7.272 × 10⁻⁵ rad/s.

b) Viewed from the North Pole, Earth's angular speed rotates in an anticlockwise direction. Therefore, the angular velocity is positive.

c) Earth's speed at a point on the equator is 463.23 m/s.

d)  the speed of a point on the earth’s surface halfway between the equator and the pole is 231.61 m/s.

Explanation:

a) The angular speed of the Earth's rotation is:

ω = 2π / T

where

T is the period

ω = 2π / (24 hr × (3600 s / 1 hr))

ω = 7.272 × 10⁻⁵ rad/s

b) Viewed from the North Pole, Earth's angular speed rotates in an anticlockwise direction. Therefore, the angular velocity is positive.

c) Earth's speed at a point on the equator is:

v = r × ω

v = (6.37 × 10⁶ m) × (7.272 × 10⁻⁵ rad/s)

v = 463.23 m/s

d) The radius of the circle in which the point moves is half of Earth's radius. Therefore,

r = 1/2(6.37 × 10⁶ m)

r = 3.19 × 10⁶ m

Therefore, the speed of a point on the earth’s surface halfway between the equator and the pole is:

v = r × ω

v = (3.19 × 10⁶ m) × (7.272 × 10⁻⁵ rad/s)

v = 231.61 m/s

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electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia