if a 5-kg bowling ball is projected upward witha velocity of 2.0 m/s, then what is the recoil velocity of the Earth(mass=6.0×10^
1 answer:
by the concept of momentum conservation we can say
if net force on a system of mass is ZERO then its momentum will remain conserved
Here a ball is projected upwards so if we take Ball + Earth as a system then total momentum of the system will remain conserved
Initially when ball is on the surface of earth the system has zero momentum and hence we can say after throwing the ball momentum of earth + ball must be zero
now using same equation we can say
given that
from above equation velocity of earth will be
so above will be the recoil speed of earth
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Answer:
The number of electrons emitted from the metal per second increases.
Explanation:
The photoelectric effect can be explained by thinking the incident light as made of many photons, each carrying an energy of
where h is the Planck constant and f is the light frequency. A photoelectron is extracted from the metal if the energy of the incoming photon, which hits the electron and gives all its energy, is at least equal to the work function of the metal, . Moreover, each photon of the incident light hits only one electron in the metal.
Given these premises, we can analyze each statement:
The work function of the metal decreases. --> FALSE. The work function is just the energy needed to extract photoelectrons from the metal: so, it depends only on the properties of the metal, and not on the intensity of the incident light.
The number of electrons emitted from the metal per second increases. --> TRUE. The intensity of the incident light is proportional to the number of photons contained in the light: so, the higher the intensity, the larger the number of photons that hit the electrons in the metal, the larger the number of electrons emitted.
The maximum speed of the emitted electrons increases. --> FALSE. The energy of the electrons emitted depends ONLY on the energy of the incoming photon, so it depends only on the frequency of the photon, not on the number of photon (intensity). In fact, only 1 photon at time hits 1 electron, so the intensity of the light does not affect the energy of the electrons (and so, it does not affect their speed)
The stopping potential increases. --> FALSE. The stopping potential is the potential needed to stop the electrons in the metal preventing them to escape the metal: this depends only on the energy of the electron, which does not depend on the intensity of the light, but only on its frequency.