The molecules of a solid vibrate faster so that they start spreading out to become a liquid. This energy makes them vibrate faster so the bonds between molecules can't interact all that well anymore creating more distance. The stronger the bonds between the molecules the higher the energy (temperature) has to be to get them away from each other. Hope I didn't confuse you too much!
Answer:
Explanation:
according to snell's law
refractive index of water n_w is 1.33
refractive index of glass n_g is 1.5
now applying snell's law between air and glass, so we have
![\beta = sin^{-1} [\frac{n_g}{n_a}*sin\alpha]](https://tex.z-dn.net/?f=%5Cbeta%20%3D%20sin%5E%7B-1%7D%20%5B%5Cfrac%7Bn_g%7D%7Bn_a%7D%2Asin%5Calpha%5D)
we know that
Since force is mass*acceleration,
F = 70kg * 9.8 m/s
The equation of motion of a pendulum is:
where 
it its length and 
is the gravitational acceleration. Notice that the mass is absent from the equation! This is quite hard to solve, but for <em>small</em> angles (
), we can use:
Additionally, let us define:
We can now write:
The solution to this differential equation is:
where 
and 
are constants to be determined using the initial conditions. Notice that they will not have any influence on the period, since it is given simply by:
This justifies that the period depends only on the pendulum's length.
