Any object that is spherical in shape would best represent a true scale model of the shape of the Earth. Examples are ping pong balls, billiard balls, marble and other smooth spherical objects. The shape of the Earth is called the oblate spheroid. The "oblate" would refer to an oblong shape and "spheroid" would refer to an almost spherical shape. The earth has on almost spherical shape and has a slightly oblong appearance. The diameter from the South pole to the north pole was measured to have a value of 12714 km while the diameter of the equator is approximately 12756 km. As you can see, the values are not equal. This makes the earth not a perfect sphere.
Answer:
Explanation:
a) The second arm measures the minutes. The difference between 9:17:30 and 9:15:00 is 2 minutes 30 seconds. This means the second arm would have revolved 2.5 times.
The circumference = 2πr= 2π(13.5 cm) = 84.823 cm
Distance = 2.5 × 84.823 cm = 212 cm = 2.12 m
b) Displacement of an object is the shortest distance between the initial and final point. Since the second arm revolves 2 and half times, we use only the half times (a semicircle)
Displacement for semicircle = 2r = 2(13.5) = 27 cm
c) Average speed = distance / time
time = 2 minutes 30 seconds = 150 seconds
Average speed = 212 cm / 150 s = 1.41 cm/s
d) Average velocity = displacement / time = 27 cm / 150 s = 0.18 cm/s
e) number of revolutions = 100 m / circumference = 100 m / 0.848 m = 117.92
but 1 revolution = 1 minute
117.92 revolution = 117 minutes 55 seconds = 1 hour 57 minutes 55 seconds
Hence the time would be: 11:12:55
Answer: C. Tissue Paper
Explanation:
When we talk about objects that are illuminated by a light source, they are classified according to the amount of light they let through them, as follows:
Transparent bodies: Those who let in almost all the light that incides them. Therefore, the intensity of the incident light is very similar to that transmitted. For example: Clear Glass
Opaque bodies: Those who do not let the light pass. For example: Cream Cheese and Orange Juice
Translucent bodies: Those that let in a portion of the incident light. That is, they let approximately half of the light that falls on them pass through. For example: Tissue Paper
<span>The equation that relates Wavelength & frequency of electromagnetic waves is :
Velocity (c) = Wavelength (λ) * frequency (f) ------ (1)
Electromagnetic wave velocity (c) = Speed of Light = 3 * 10^8 m/s
From (1),
Wavelength , λ = c / f
λ= (3*10^8)/(980*10^3)
λ = 306.12 m
Minimum height of the antenna for effective transmission = λ * 0.5 = 306.12*0.5
Answer : 153 m (rounded off)</span>
