Ask question

Ask question

All categories

3 years ago

13

Why is it easy to remove air from balloon and is difficult to remove air from glass bottle

1 answer:

Lera25 [3.4K]3 years ago

4 0

This is harder because the glass is solid

You might be interested in

Select the correct answer.

wolverine [178]

The answer is C in this question.

5 0

3 years ago

Read 2 more answers

A 0.73-m aluminum bar is held with its length parallel to the east-west direction and dropped from a bridge. Just before the bar

Tasya [4]

Answer:

A) B = 5.4 10⁻⁵ T, B) the positive side of the bar is to the West

Explanation:

A) For this exercise we must use the expression of Faraday's law for a moving body

fem = $- \frac{d \phi }{dt}$

fem = $- \frac{d (B l y}{dt}= - B l v$ - d (B l y) / dt = - B lv

B = $- \frac{fem}{l \ v}$

we calculate

B = - 7.9 10⁻⁴ /(0.73 20)

B = 5.4 10⁻⁵ T

B) to determine which side of the bar is positive, we must use the right hand rule

the thumb points in the direction of the rod movement to the south, the magnetic field points in the horizontal direction and the rod is in the east-west direction.

Therefore the force points in the direction perpendicular to the velocity and the magnetic field is in the east direction; therefore the positive side of the bar is to the West

4 0

3 years ago

The wavelength you entered in the last problem is related to the energy required to eject an electron from sodium metal, the so-

I am Lyosha [343]

Answer:

2.30 eV

Explanation:

Some details of the problem are missing:

"Light of wavelength 540 nm is required to extract electrons from sodium. What is the work function of sodium?"

The equation that describes the photoelectric effect is

$\frac{hc}{\lambda}=\phi +K$

where:

$\frac{hc}{\lambda}$ is the energy of the incoming photon, with

$h=6.63\cdot 10^{-34} Js$ is Planck constant

$c=3.0\cdot 10^8 m/s$ is the speed of light

$\Phi$ is the work function of the material

K is the maximum kinetic energy of the emitted photoelectrons

The minimum energy needed by the photons to extract the photoelectrons is that for which the kinetic energy is zero, so

K = 0

Therefore we have

$\frac{hc}{\lambda}=\phi$

In this problem, we know that the wavelength of the incoming light is

$\lambda=540 nm = 540\cdot 10^{-9}m$

Therefore, we can find the work function of sodium:

$\phi=\frac{hc}{\lambda}=\frac{(6.63\cdot 10^{-34})(3\cdot 10^8)}{540\cdot 10^{-9}}=3.68\cdot 10^{-19}J$

And converting into electronvolts,

$\phi=\frac{3.68\cdot 10^{-19}J}{1.6\cdot 10^{-19}}=2.30 eV$

5 0

3 years ago

If the amplitude of vibration is large sound is feeble true or false

yanalaym [24]

Answer:

False

Explanation:

7 0

4 years ago

An object on the end of a spring is set into oscillation by giving it an initial velocity while it is at its equilibrium positio

Murrr4er [49]

Explanation:

It is given that, in the first trial, the initial velocity is $v_o$ and in the second it is $4v_o$ .

The total energy of the system remains constant. So,

$\dfrac{1}{2}mv^2+\dfrac{1}{2}kx^2=\text{constant}$ ....(1)

x is amplitude

It means that the amplitude is directly proportional to velocity. If velcoity increases to four times, then the amplitude also becomes 4 times.

Differentiating equation (1) we get :

$mv\dfrac{dv}{dt}+kx\dfrac{dx}{dt}=0$

Since,

$\dfrac{dv}{dt}=a,\ \text{acceleration}$ and $\dfrac{dx}{dt}=v,\ \text{velocity}$

So,

$mva+kxv=0$

It means that the acceleration is also proportional to the amplitude. So, acceleration also becomes 4 times.

Hence, the correct option is (B) "both the amplitude and the maximum acceleration are four times as great"

7 0

4 years ago