Answer:
I Think its ABC
Explanation:
No air is the lightest
Helium is lighter than regular air that's why it goes up so then the regular air would be heaviest.
Anything that has mass has weight and anything that has weight has mass simple.
Explanation:
d) Magnetic force is the power that pulls materials together (magnet e. g iron)
an example :how magnet can pick up a coin.
e) frictional force produces when two surfaces are in contact with each other.
effects of friction : I) it produces heat
II) it causes loss in power.
Answer:
Explanation: I think...
Thermal Energy formula Q = mcΔT
Q = Thermal Energy(J)
m = Mass(kg)
c = Specific Heat(J/kg°C)
ΔT = Change in Temperature(°C)
you have to write the equation based on what you are working on
Answer:

Explanation:
From the question we are told that:
Frequency of 3rd harmonics 
Frequency of 5th harmonics 
Generally the equation for Wavelength at 3rd Harmonics is mathematically given by

Therefore

Generally the equation for Wavelength at 1st Harmonics is mathematically given by

Therefore

Generally the equation for the frequency of the first harmonic is mathematically given by


