Answer:
A) some of the rocks energy is transformed to thermal energy
Explanation:
If we neglect air resistance during the fall of the rock, than the mechanical energy of the rock (which is sum of its potential energy and its kinetic energy) would be constant during the entire motion, so the total energy of the rock at the top would be the same as the sum of its potential energy and kinetic energy at the bottom.
However, this not occurs, due to the presence of air resistance. In fact, air resistance acts against the fall of the rock, and because of the friction between the molecules of air and the surface of the rock, the rock loses part of its energy. This energy is converted into thermal energy of the molecules of the air.
Answer:
0.12 K
Explanation:
height, h = 51 m
let the mass of water is m.
Specific heat of water, c = 4190 J/kg K
According to the transformation of energy
Potential energy of water = thermal energy of water
m x g x h = m x c x ΔT
Where, ΔT is the rise in temperature
g x h = c x ΔT
9.8 x 51 = 4190 x ΔT
ΔT = 0.12 K
Thus, the rise in temperature is 0.12 K.
Answer:
Explanation:
a ) AM radio band (540–1600 kHz)
frequency = 540 kHz = 540 x 10³ Hz
wave length = velocity of light / frequency
= 3 x 10⁸ / 540 x 10³
= 555.55 m
frequency = 1600 kHz = 1600 x 10³ Hz
wave length = velocity of light / frequency
= 3 x 10⁸ / 1600 x 10³
= 187.5 m
maximum wavelength = 555.55 m
minimum wavelength = 187.5 m
b )
AM radio band (88 - 108 MHz)
frequency = 88 MHz = 88 x 10⁶ Hz
wave length = velocity of light / frequency
= 3 x 10⁸ / 88 x 10⁶
= 3.41 m
frequency = 108 MHz = 108 x 10⁶ Hz
wave length = velocity of light / frequency
= 3 x 10⁸ / 108 x 10⁶
= 2.78 m
maximum wavelength = 3.41 m
minimum wavelength = 2.78 m
