Answer:
Sound and light are similar in that both are forms of energy that travel in waves. They both have properties of wavelength, freqency and amplitude. Here are some differences: Sound can only travel through a medium (substance) while light can travel through empty space.
Answer:
1.785 m/s
Explanation:
The momentum can be calculated using the expression below
M1 *V1 + M2 * V2 = (M1+M2) V3
M1= mass of van=9000 kg
M2= mass of car= 850kg
V3= velocity of entangled car
V1= Velocity of the van= 0
V2= velocity of the car= 5 m/ s
Substitute the values
(900×0) + (500×5)=( 900+500)× V3
2500=1400 V3
V3=2500/1400
V3= 1.785 m/s
Hence, velocity of the entangled cars after collision is 1.785 m/s
Since energy cannot be created nor destroyed, the change in energy of the electron must be equal to the energy of the emitted photon.
The energy of the emitted photon is given by:

where
h is the Planck constant
f is the photon frequency
Substituting

, we find

This is the energy given to the emitted photon; it means this is also equal to the energy lost by the electron in the transition, so the variation of energy of the electron will have a negative sign (because the electron is losing energy by decaying from an excited state, with higher energy, to the ground state, with lower energy)