The Electromagnetic spectrum.
Answer:
After 4 s of passing through the intersection, the train travels with 57.6 m/s
Solution:
As per the question:
Suppose the distance to the south of the crossing watching the east bound train be x = 70 m
Also, the east bound travels as a function of time and can be given as:
y(t) = 60t
Now,
To calculate the speed, z(t) of the train as it passes through the intersection:
Since, the road cross at right angles, thus by Pythagoras theorem:
Now, differentiate the above eqn w.r.t 't':
For t = 4 s:
If you have a lump of solid at its melting point ... like ice at 32°F ...
you have to put a certain amount of heat into it just to change it
to water at 32°F. That amount of heat, that's used just to change
a solid lump into liquid without changing its temperature, is called
the heat of fusion for that substance.
The number is different for every substance.
For water, it takes 336 joules of heat to melt 1 gram of ice
into 1 gram of water, all at 32°F (0°C).
That's an enormous latent heat of fusion ... more than almost any
other known substance. That's why ice is such a good choice
when you need something to put in your drink to cool it down.
Ice absorbs a huge amount of heat before it melts and the drink
gets watered down.
The complete sentence is:
A calorimeter directly measures changes in temperature in order to calculate specific heat.
In fact, the amount of energy acquired/released by a substance is directly proportional to its change in temperature due to the equation
where Q is the amount of energy, m is the mass of the substance, Cs is the specific heat of the substance and 
is the change in temperature. Therefore, by knowing Q, m and by measuring the change in temperature, it is possible to calculate Cs, the specific heat capacity of the substance.
<em>The </em><em>nucleus</em><em> has most of the atomic mass in an atom. The </em><em>nucleus</em><em> is made up of protons and neutrons.</em>
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