Answer:
B. They usually need to be cooled to dissipate thermal energy build-up and prevent damage.
Explanation:
High energy mechanical devices needs to be cooled down because they have moving parts which creates heat which may affect the other electrical and electronic component of the device. Because quality of material changes with the temperature. If high temperature occur might change the shape of that component and may affect the efficiency of the machine.
Since the horizontal velocity is what is doubled, that does not affect the fall of the ball, thus the fall is still 5 seconds long.
<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>
Answer:
893 Newtons
Explanation:
m = Mass of Usain Bolt = 94 kg
a = Acceleration of Usain Bolt in the first 0.89 seconds = 9.5 m/s²
From Newton's Second law
Force
The average horizontal force exerted by Bolt against the ground during the first 0.890 s of the race is 893 Newtons
T2=r In the form of Kepler's law that can use to relate the period T and radius of the planet in our solar systems
<u>Explanation:</u>
<u>Kepler's third law:</u>
- Kepler's third law states that For all planets, the square of the orbital
period (T) of a planet is proportional to the cube of the average orbital radius (R).
- In simple words T (square) is proportional to the R(cube) T²2 ∝1 R³3
- T2 / R3 = constant = 4π ² /GM
where G = 6.67 x 10-11 N-m2 /kg2
M = mass of the foci body
