Answer:
B
Explanation:
hair can be a safety hazard
Explanation :
Absorption coefficient of a material determines how much sound is absorbed by the material.
To build a soundproof room, Heavy curtains and carpet can be used. They reduce reverberation.
Reverberation means an echoing sound which persists for some time. For example, when we bang on a huge piece of metal, we hear the reverberation even after we stop banging.
Hence, option (A) and (D) are correct.
<span>Which of the following substance are not formed by chemical bonds? </span>A MIXTURE
Answer:
time = 6.67secs
Explanation:
power = workdone( energy) / time
therefore :
Time = workdone / power
time = 500 / 75
time = 6.67secs
