The first excited state of a particular atom in a gas is 5.8 eV above the ground state. A moving electron collides with one of these atoms, and excites the atom to its first excited state. Immediately after the collision the kinetic energy of the electron is 3.7 eV. What was the kinetic energy of the electron just before the collision? Ki = eV

E₀ = 9.5 eV

Explanation:

In the processes of absorption, excitation and shocks the energy must be conserved therefore the energy before the shock is

         E₀ = E_excitation + E_residual

         E₀ = 5.8 + 3.7

         E₀ = 9.5 eV

this is the energy of the electron before the collision

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

                                              ⇒      

here   k is the proportionality constant whose value is 1.

                                                            [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.