<u>Answers
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1) B. longitudinal.
2) B. air is cooler than the ground.
<u>Explanation
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Q1
There are two categories of a wave. That is transverse and longitudinal waves. Transverse waves forms crests and troughs while longitudinal forms compressions and rarefaction as they travel. Rarefactions are regions where the wavelengths are longer than other regions.
Q2
As the ray of light moves from an optically less dense to a more dense region it bends towards the normal.
If the sound is bending away from the earth's surface, then the ground must be warmer than the air. As the sound travels it moves from optically dense medium to a less dense medium. For this reason it bends away from the normal. This can only happen when, B. air is cooler than the ground.
Answer:
Not all of the time, it can also depend on the strength of the magnet.
Explanation:
say you have a small very strong magnet, that might work just as well as a large but week magnet.
Answer:
The frequency of the second wave is half of the frequency of first one.
Explanation:
The wavelength of the second wave is double is the first wave.
As we know that the frequency is inversely proportional to the wavelength of the velocity is same.
velocity = frequency x wavelength
So, the ratio of frequency of second wave to the first wave is

The frequency of the second wave is half of the frequency of first one.
Answer:
It will take 0.0611 sec for nerve signal to travel 1.1 m
Explanation:
We have given the nerve cell connecting the spinal card to feet is 1.1 m long
So length d = 1.1 m
And speed of the nerve impulse v = 18 m/sec
We have to find the time for nerve signal to travel that distance
Speed of the nerve signal is given by 
So 
So it will take 0.0611 sec for nerve signal to travel 1.1 m