Time t = ?
<span>When wave is moving from
y = 0 to y =12 cm</span>
By using the formula,
y = 15cos [(π/12) t)] =
0,
cos [(π/12) t)] = 0 =
cos (π/2), so,
(π/12)t = π/2,
t = (π/2) (12/π)
t = 12/2
<span>t = 6 sec</span>
<span>so 6 sec is the least amount of time required</span>
Λ = 3*10^8 / 9*10^8 = 1/3 m
no. of wavelengths = 60/(1/3) = 180
Based on the given, this is probably a gravitational potential energy problem (PEgrav). The formula for PEgrav is:
PEgrav = mgh
Where:
m = mass (kg)
g = acceleration due to gravity
h = height (m)
With this formula you can derive the formula for your unknown, which is mass. First put in what you know and then solve for what you do not know.

![30J=m(10)(10[tex] \frac{30}{100} =m](https://tex.z-dn.net/?f=30J%3Dm%2810%29%2810%5Btex%5D%20%5Cfrac%7B30%7D%7B100%7D%20%3Dm)
)[/tex]
Do operations that you can with what is given first.

Transpose the 100 to the other side of the equation. Do not forget that when you transpose, you do the opposite operation.
m = 0.30kg
The three phases of matter differ in properties just because of the proximity of their molecules. The solid phase is the most organized of all. Its atoms are compactly arranged together and has the strongest intermolecular forces to keep them together. This is why they have a definite shape and volume. The liquid phase have molecules that are far away from each other, but not as far as that of the gas phase. The liquid and gas phases can be lumped into one group called fluids because they have the same property - they take the shape and volume of their container.
To make an analogy, see the attached picture for your reference.