Answer:
Too old(Ex. if real time is 1000 then they estimate >1000)
Explanation:
This is because with time our planet may have a definite function which describes temperature.(Because of all the factors and global warming except nuclear bomb testing)
Now nuclear test on planet have significant effect on temperature rise.
Also 14°C rise in temperature is good one because of this.
If future archaeologists only consider that uniform function as above mentioned then they estimate more time then the real one.
Thus too old is right answer.
<u>Answer :</u>
(a) d = 0.25 m
(b) d = 0.5 m
<u>Explanation :</u>
It is given that,
Frequency of sound waves, f = 686 Hz
Speed of sound wave at 
is, v = 343 m/s
(1) Perfectly destructive interference occurs when the path difference is half integral multiple of wavelength i.e.
........(1)
Velocity of sound wave is given by :
Hence, when the speakers are in phase the smallest distance between the speakers for which the interference of the sound waves is perfectly destructive is 0.25 m.
(2) For constructive interference, the path difference is integral multiple of wavelengths i.e.
( n = integers )
Let n = 1
So, 
Hence, the smallest distance between the speakers for which the interference of the sound waves is maximum constructive is 0.5 m.
Answer:
176 min
Explanation:
456 g = .456 kg
Specific heat of ice s = 2093 J kg⁻¹
Heat required to raise the temperature by 25 degree
= mass x specific heat x rise in temperature.
= .456 x 2093 x 25
=23860 J
Heat required to melt the ice to make water at zero degree
= mass x latent heat
= .456 x 334 x 10³
=152304 J
Total heat required = 152304 + 23860 = 176164 J .
Time Required = Heat required / rate of supply of heat
= 176164 / 1000
176.16 min
Answer:
it is option 3
Explanation:
because as red shift occurs when object in a space is far from us, so many of the stars we know will be seen in red shift because they are far from us by 20 years the most of the starts we see will be in red shift
