Questions

We know that,

The equivalent K =  L1 + L2L1K1+L2K2

where L1 & L2 are plate1 & Plate2 thicknesses, K1 & K2 are coefficient thermal conductivity of plate1 & Plate2 respectively.

But here L1 = L2 = L (say)

Then K = L+L/(L/K1 + L/K2)  =  2K1K2K1+K2

It is connected to the sea by a channel cut through solid rock and sand. 

The given letter equation implies that, 

7 C in the R = 7 Colours in a Rainbow.

The elements in the same column will have similar properties. Beryllium is the group II element. Group II elements are magnesium, calcium, strontium, barium and radium. Hence, these show the similar prperties.

An object at rest may have Potential energy.

The hertz (Hz) is defined as one cycle per second and is a SI unit of frequency. Here kilohertz is also a unit of frequency of waves and is defined as 1000 cycles per second. Radio waves are measured in kilohertz (KHz).

In the given puzzle the logic is

2 x 1 + 1 = 2 + 1 = 3

3 x 2 + 2 = 6 + 2 = 8

4 x 3 + 3 = 12 + 3 = 15

5 x 4 + 4 = 20 + 4 = 24

6 x 5 + 5 = 30 + 5 = 35

Similarly,

7 x 6 + 6 = 42 + 6 = 48

7 = 48.