The pendulum bob is dropped from point a and swings to point c. the pendulum bob swings back and forth but eventually it stops. why?
a) all the potential energy is converted to kinetic energy.
b) the external energy source is less than the friction force.
c) there cannot be continued motion without an external energy source.
d) all the kinetic energy is converted to potential energy or energy of position.

Glass is transparent to visibile light under normal conditions; however, at extremely high intensities, glass will absorb most of the light incident upon it. this works through a process known as multiphoton absorption. in this process, several photons are absorbed at the same time. if very intense light whose photons carry 2ev of energy is shined onto a material with a band gap of 4ev, that light can be absorbed through two-photon absorption, because two photons have the right amount of energy to bridge the band gap. what is the minimum number of photons of 800-nm light that are needed to equal or exceed the band gap of fused silica glass

What is the most useful equation for electric power?

If 2 moles of co_2 at 2l and 500k are expanded reversibly to 20l, more work can be obtained from an adiabatic process than from an isothermal process. is the above statement true or false?