Which statement best describes longitudinal waves?

A uniform horizontal beam of weight 481 N and length 3.32 m has two weights hanging from it. One weight of 381 N is located 0.87

Andre45 [30]

Answer:

1143 N at 1.59 m from the left end

Explanation:

For the system to produce equilibrium, the total force and moment must be 0. Since the total weight downward is

481 + 381 + 281 = 1143 N

Therefore the magnitude of the force acting upward to balance this system must be the same of 1143 N

That alone is not enough, we also need the position of the force for the total moment to be 0.

Let x be the length from the this upward force to the left side. And let the left point be the point of reference for moment arm:

481 * 3.32/2 + 381 * 0.8798 + 281*(3.32 - 0.8798) - 1143*x = 0

x = (481*1.66 + 381 * 0.8798 + 281*2.4402)/1143 = 1.59m

5 0

4 years ago

In a particular experiment to study the photoelectric effect, the frequency of the incident light and the temperature of the met

Molodets [167]

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

$E=hf$

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, $\phi$ . 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.

4 0

3 years ago

how is momentum conserved when a cue ball moving with a velocity of 1.5 m/s strikes another billiard ball white playing pool? Sh

mote1985 [20]

according to conservation of momentum , total sum of momentum of the objects taking part in a collision is same before and after the collision.

Total momentum before collision = Total momentum after the collision

when a cue ball moving at velocity 1.5 m/s hits a billiard ball , transfer of momentum takes place between the balls such that total sum of momentum of cue ball and billiard ball remain same before and after the collision.

hence we say that the momentum is conserved.

8 0

3 years ago

The gravitational force exerted by a proton on an electron is 2x1039 times weaker than the electric force that the proton exerts

pickupchik [31]

To solve this problem we will rely on the theorems announced by Newton and Coulomb about the Gravitational Force and the Electrostatic Force respectively.

In the case of the Force of gravity we have to,

$F_g = G\frac{m_pm_e}{d^2}$