Answer:
False
Explanation:
The given statement "Two objects must be in contact for them to exert a force on each other" is not true as there are many types of forces that doesn't require being in contact for exerting a force.
One such example is the gravitational force acting between two bodies. Gravitational force is the force of pull with which a body pulls another body without being in contact.
For two bodies of masses 'M' and 'm' separated at a distance of 'R', the gravitational force is given as:

The gravitational force acts always act between bodies that have mass. The bodies are not in contact yet experience force.
Therefore, the given statement is false.
power received will always remain same and does not depends on the distance
it will be same as the power of source

now the energy released by one photon is given as



now let say N photons per second released


Answer:
v = K √(E / ρ)
Explanation:
Modulus of elasticity has units of N/m², or kg/m/s².
Density has units of kg/m³.
Velocity has units of m/s.
If we divide modulus of elasticity by density, we can eliminate kg:
E / ρ = [kg/m/s²] / [kg/m³]
E / ρ = [m²/s²]
Taking the square root gets us units of velocity:
√(E / ρ) = [m/s]
Multiply by the constant K:
v = K √(E / ρ)