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3 years ago

Which statement describes a controlled experiment?

Physics

1 answer:

olga_2 [115]3 years ago

7 0

Answer:

In a controlled experiment, an independent variable (the cause) is systematically manipulated and the dependent variable (the effect) is measured; any extraneous variables are controlled. The researcher can operationalize (i.e. define) the variables being studied so they can be objectivity measured.

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A massless rod of length L has a small mass m fastened at its center and another mass m fastened at one end. On the opposite end

konstantin123 [22]

Answer:

onservation of energy

U top = K bottom

(m + m)*g*L = 1/2*I*?^2 where I = m*(L/2)^2 + m*L^2 = 1.25*m*L^2

So 2m*g*L = 1/2*1.25*m*L^2*?^2

So ? = sqrt(3*g*/(1.25*L) ) = sqrt(12g/5L)

3 0

2 years ago

Red light of wavelength 651 nm produces photoelectrons from a certain photoemissive material. Green light of wavelength 521 nm p

Mnenie [13.5K]

Answer:

material work function is 0.956 eV

Explanation:

given data

red wavelength 651 nm

green wavelength 521 nm

photo electrons = 1.50 × maximum kinetic energy

to find out

material work function

solution

we know by Einstein photo electric equation that is

for red light

h ( c / λr ) = Ф + kinetic energy

for green light

h ( c / λg ) = Ф + 1.50 × kinetic energy

now from both equation put kinetic energy from red to green

h ( c / λg ) = Ф + 1.50 × (h ( c / λr ) - Ф)

Ф =( hc / 0.50) × ( 1.50/ λr - 1/ λg)

put all value

Ф =( 6.63 × $10^{-34}$ (3 × $10^{8}$ ) / 0.50) × ( 1.50/ λr - 1/ λg)

Ф =( 6.63 × $10^{-34}$ (3 × $10^{8}$ ) / 0.50 ) × ( 1.50/ 651× $10^{-9}$ - 1/ 521 × $10^{-9}$ )

Ф = 1.5305 × $10^{-19}$ J × ( 1ev / 1.6 × $10^{-19}$ J )

Ф = 0.956 eV

material work function is 0.956 eV

4 0

2 years ago

Read 2 more answers

Which atomic model proposed that electrons move in specific orbits around the nucleus of an atom

BabaBlast [244]

Bohr's atomic model

8 0

3 years ago

Which type of electromagnetic radiation may damage central nervous system

Furkat [3]

Answer:

microwaves

Explanation:

microwaves do emit radiation, technically speaking, but it's not the DNA-damaging radiation we're used to hearing about. Microwaves, along with radio waves from (you guessed it) radio and cell phone towers, are types of non-ionizing radiation.

5 0

3 years ago

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The vapor pressure of benzene, C6H6, is 40.1 mmHg at 7.6°C. What is its vapor pressure at 60.6°C? The molar heat of vaporization

ANEK [815]

Answer:

The vapor pressure at 60.6°C is 330.89 mmHg

Explanation:

Applying Clausius Clapeyron Equation

$ln(\frac{P_2}{P_1}) = \frac{\delta H}{R}[\frac{1}{T_1}- \frac{1}{T_2}]$

Where;

P₂ is the final vapor pressure of benzene = ?

P₁ is the initial vapor pressure of benzene = 40.1 mmHg

T₂ is the final temperature of benzene = 60.6°C = 333.6 K

T₁ is the initial temperature of benzene = 7.6°C = 280.6 K

ΔH is the molar heat of vaporization of benzene = 31.0 kJ/mol

R is gas rate = 8.314 J/mol.k

$ln(\frac{P_2}{40.1}) = \frac{31,000}{8.314}[\frac{1}{280.6}- \frac{1}{333.6}]\\\\ln(\frac{P_2}{40.1}) = 3728.65 (0.003564 - 0.002998)\\\\ln(\frac{P_2}{40.1}) = 3728.65 (0.000566)\\\\ln(\frac{P_2}{40.1}) = 2.1104\\\\\frac{P_2}{40.1} = e^{2.1104}\\\\\frac{P_2}{40.1} = 8.2515\\\\P_2 = (40.1*8.2515)mmHg = 330.89 mmHg$

Therefore, the vapor pressure at 60.6°C is 330.89 mmHg

6 0

3 years ago

Read 2 more answers