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3 years ago

Which statement correctly describes the motion on which an Earth time interval is based?

1 answer:

4 0

The smswer is b because if there is no day there will be no month so mo year too as it takes the earth to spin 24 hours around so 24 hours is a day.

You might be interested in

What is the SI unit of pressure? A. g/cm3 B. the pascal C. the newton D. m/s2

sesenic [268]

The basic definition of pressure is force/area and the scientific community defined that as the Pascal (Pa).

6 0

3 years ago

Read 2 more answers

The statement “Heavy objects fall faster than light objects” is an example of a(n) _______.

vazorg [7]

D. Theory is the answer

7 0

3 years ago

The following table lists the work functions of a few common metals, measured in electron volts. Metal Φ(eV) Cesium 1.9 Potassiu

Citrus2011 [14]

A. Lithium

The equation for the photoelectric effect is:

$E=\phi + K$

where

$E=\frac{hc}{\lambda}$ is the energy of the incident light, with h being the Planck constant, c being the speed of light, and $\lambda$ being the wavelength

$\phi$ is the work function of the metal (the minimum energy needed to extract one photoelectron from the surface of the metal)

K is the maximum kinetic energy of the photoelectron

In this problem, we have

$\lambda=190 nm=1.9\cdot 10^{-7}m$ , so the energy of the incident light is

$E=\frac{hc}{\lambda}=\frac{(6.63\cdot 10^{-34}Js)(3\cdot 10^8 m/s)}{1.9\cdot 10^{-7} m}=1.05\cdot 10^{-18}J$

Converting in electronvolts,

$E=\frac{1.05\cdot 10^{-18}J}{1.6\cdot 10^{-19} J/eV}=6.5 eV$

Since the electrons are emitted from the surface with a maximum kinetic energy of

K = 4.0 eV

The work function of this metal is

$\phi = E-K=6.5 eV-4.0 eV=2.5 eV$

So, the metal is Lithium.

B. cesium, potassium, sodium

The wavelength of green light is

$\lambda=510 nm=5.1\cdot 10^{-7} m$

So its energy is

$E=\frac{hc}{\lambda}=\frac{(6.63\cdot 10^{-34}Js)(3\cdot 10^8 m/s)}{5.1\cdot 10^{-7} m}=3.9\cdot 10^{-19}J$

Converting in electronvolts,

$E=\frac{3.9\cdot 10^{-19}J}{1.6\cdot 10^{-19} J/eV}=2.4 eV$

So, all the metals that have work function smaller than this value will be able to emit photoelectrons, so:

Cesium

Potassium

Sodium

C. 4.9 eV

In this case, we have

- Copper work function: $\phi = 4.5 eV$

- Maximum kinetic energy of the emitted electrons: K = 2.7 eV

So, the energy of the incident light is

$E=\phi+K=4.5 eV+2.7 eV=7.2 eV$

Then the copper is replaced with sodium, which has work function of

$\phi = 2.3 eV$

So, if the same light shine on sodium, then the maximum kinetic energy of the emitted electrons will be

$K=E-\phi = 7.2 eV-2.3 eV=4.9 eV$

7 0

4 years ago

What type of light is a glow stick

Otrada [13]

Answer:

self-contained, short-term light-source

Explanation:

7 0

3 years ago

A tank of water has a length 10.0 m, width 5.00 m, and depth 2.50 m. What the absolute pressure at the bottom of the tank?

Damm [24]

Answer:

1.28 x 10^5 Pa

Explanation:

The absolute pressure at the bottom of the tank of water is given by:

$p= p_0 + \rho g h$

where

$p_0 = 1.03 \cdot 10^5 Pa$ is the atmospheric pressure

$\rho = 1000 kg/m^3$ is the water density

g = 9.8 m/s^2 is the acceleration of gravity

h = 2.50 m is the heigth of the column of water

Substituting into the formula, we find

$p=1.03\cdot 10^5 +(1000)(9.8)(2.50)=1.28\cdot 10^5 Pa$

6 0

3 years ago