A firecracker before been lit has potential energy in it. It is chemical potential energy which is due to the explosives in it.When it is lit, it gets converted into heat,light and kinetic energy.
The beats are actually two new sounds.
Their frequencies are (the sum of the original two frequencies) and (the difference of the original two frequencies).
The existence of the beats is the result of the difference in the frequencies of the original two sounds. <em> (b)</em>
Answer:B 20 newtons opposite to the direction of the applied force
Explanation: