I would think it is B I am not certain though..
First thermal energy (heat) is not the same thing as temperature. Thermal energy is internal energy held by the molecules but the temperature is the is the effect of the heat. Temperature is the measurement of the heat energy. Also, thermal energy depends on the size of the matter but the temperature isn't, it's just the average heat energy held by the matter.
N₀ = number of radioactive atoms initially present = 128
N = number of radioactive atoms left after time "t" = 2
t = time taken
T = half life period for the radioactive metal = 20 years
λ = decay constant = ?
decay constant is given as
λ = 0.693/T
inserting the values
λ = 0.693/20
λ = 0.0347
number of radioactive atoms left after time "t" is given as
N = N₀
inserting the values
2 = (128)
t = 120 years
Answer:
Explanation:
frequency of tuning fork = 440 Hz
wave length λ = velocity of sound / frequency
= 343 / 440 m
= .7795 m
= 77.95 cm
λ = 77.95 cm
Let length of rod having fundamental wavelength of 77.95 cm be L
L = λ /2
L = 77.95 / 2
= 38.975 cm .
length of rod = 38.975 cm .
= 0. 39 m