It slowly cools an hardens,eventually turning into igneous rock<span />
Explanation:
avg spd = total distance/total time
=80/8=10m/s
data which is expressed in form of following way

here in above expression
= true value
= uncertainty in the value
now the relative uncertainty is given as

now by above formula we can say
a) 2.70 ± 0.05cm
here
True value = 2.70
uncertainty = 0.05
Relative uncertainty =
= 0.0185
b) 12.02 ± 0.08cm
here
True value = 12.02
uncertainty = 0.08
Relative uncertainty =
= 0.00665
Answer: A crest is the highest point the medium rises to and a trough is the lowest point the medium sinks to. It is also a point on the wave where the displacement of the medium is at a maximum.