How hot or cold something is
How much heat is absent (measuring the absence if heat)
(Fun fact- there is no cold just absence of heat
Answer:
From lowest to highest acceleration:
3rd train
2nd train
1st train
Explanation:
The acceleration of an object can be found by using Newton's second law:

where
a is the acceleration
F is the net force on the object
m is the mass of the object
We notice that for equal values of the forces F, the acceleration a is inversely proportional to the mass, m. Therefore, greater mass means lower acceleration, and viceversa.
So, the train with lowest acceleration is the one with largest mass, i.e. the 3rd train consisting of 50 equally loaded freight cars. Then, the 2nd train has larger acceleration, since it consists of 50 empty freight cars (so its mass is smaller). Finally, the 1st train (a single empty car) is the one with largest acceleration, since it is the train with smallest mass.
Answer:

Explanation:
P = Power Output = 1000 W
r = Radius = 35000000 m
= Permittivity of free space = 
c = Speed of light = 
Intensity of Electric radiation is given by

Intensity of Electric radiation is given by

The amplitude of the electric field vector is 
Answer:
5s
Explanation:
-A period is the time it takes to make one full back-and-forth swing.
-A period is calculated as the time taken for a complete swing divided by one cycle:

Hence, the period of the pendulum is 5s