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Aleks [24]
3 years ago
8

If two objects are the same size but one object is 3 times hotter than the other object, the hotter object emits If two objects

are the same size but one object is 3 times hotter than the other object, the hotter object emits 3 times more energy per time per area. 9 times more energy per time per area. 12 times more energy per time per area 81 times more energy per time per area. none of the above
Physics
1 answer:
Illusion [34]3 years ago
8 0

Answer:

81 times the first body

Explanation:

Let the temperature of the first object is T.

The temperature of the second object is 3T.

According to the Stefan's law, the energy radiated per unit area per unit time is given by

E \alpha T^{4}

So, for the first body

E_{1} \alpha T^{4}      .... (1)

for the second body

E_{2} \alpha (3T)^{4}    ..... (2)

By equation (1) and (2),

E2 = 81 times E1

So, the second body gives 81 times more energy per unit area per unit time

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A student calculates the density of a copper cube to be 4.15 g/cm . If the accepted value is 8.64 g/cm the percentage error in h
Helen [10]

 The percentage error in his experimental value is -51.97%.

<h3>What is percentage error?</h3>

This is the ratio of the error to the actual measurement, expressed in percentage.

To calculate the percentage error of the student, we use the formula below.

Formula:

  • Error(%) = (calculated value-accepted value)100/(accepted............. Equation 1

From the question,

Given:

  • Calculated value = 4.15 g/cm
  • accepted value = 8.64 g/cm

Substitute these values into equation 1

  • Error(%) = (4.15-8.64)100/8.64
  • Error(%) = -4.49(100)/8.64
  • Error(%) = -449/8.64
  • Error(%) = -51.97 %

 

Hence, The percentage error in his experimental value is -51.97%.

Learn more percentage error here: brainly.com/question/5493941

8 0
2 years ago
A merry-go-round spins freely when Diego moves quickly to the center along a radius of the merry-go-round. As he does this, it i
lianna [129]

Answer:

<em>A) the moment of inertia of the system decreases and the angular speed increases. </em>

Explanation:

The complete question is

A merry-go-round spins freely when Diego moves quickly to the center along a radius of the  merry-go-round. As he does this, It is true to say that

A) the moment of inertia of the system decreases and the angular speed increases.

B) the moment of inertia of the system decreases and the angular speed decreases.

C) the moment of inertia of the system decreases and the angular speed remains the same.

D) the moment of inertia of the system increases and the angular speed increases.

E) the moment of inertia of the system increases and the angular speed decreases

In angular momentum conservation, the initial angular momentum of the system is conserved, and is equal to the final angular momentum of the system. The equation of this angular momentum conservation is given as

I_{1} w_{1} = I_{2} w_{2}    ....1

where I_{1} and I_{2} are the initial and final moment of inertia respectively.

and w_{1} and w_{2} are the initial and final angular speed respectively.

Also, we know that the moment of inertia of a rotating body is given as

I = mr^{2}    ....2

where m is the mass of the rotating body,

and r is the radius of the rotating body from its center.

We can see from equation 2 that decreasing the radius of rotation of the body will decrease the moment of inertia of the body.

From equation 1, we see that in order for the angular momentum to be conserved, the decrease from I_{1} to I_{2} will cause the angular speed of the system to increase from w_{1} to w_{2} .

From this we can clearly see that reducing the radius of rotation will decrease the moment of inertia, and increase the angular speed.

7 0
3 years ago
Plain electromagnetic wave (in air) has a frequency of 1 MHz and its B-field amplitude is 9 nT a. What is the wavelength in air?
Norma-Jean [14]

Answer:

Part a)

\lambda = 300 m

Part b)

E = 2.7 N/C

Part c)

I = 9.68 \times 10^{-3} W/m^2

P = 3.22 \times 10^{-11} N/m^2

Explanation:

Part a)

As we know that frequency = 1 MHz

speed of electromagnetic wave is same as speed of light

So the wavelength is given as

\lambda = \frac{c}{f}

\lambda = \frac{3\times 10^8}{1\times 10^6}

\lambda = 300 m

Part b)

As we know the relation between electric field and magnetic field

E = Bc

E = (9 \times 10^{-9})(3\times 10^8)

E = 2.7 N/C

Part c)

Intensity of wave is given as

I = \frac{1}{2}\epsilon_0E^2c

I = \frac{1}{2}(8.85 \times 10^{-12})(2.7)^2(3\times 10^8)

I = 9.68 \times 10^{-3} W/m^2

Pressure is defined as ratio of intensity and speed

P = \frac{I}{c} = \frac{9.68\times 10^{-3}}{3\times 10^8}

P = 3.22 \times 10^{-11} N/m^2

6 0
3 years ago
What is called gravity ​
Harrizon [31]
Gravity is also called gravitation
3 0
3 years ago
Natalie accelerate her skateboard along a straight path from 0 m/s to 4.0 m/s in 2.5 s. find her average acceleration
Vikentia [17]
Acceleration=(speed end - speed start)/ time
Data:
speed end=4 m/s
speed start=0 m/s
time=2.5 s

acceleration=(4 m/s - 0 m/s)/2.5 s=1.6 m/s²

Answer: the acceleration would be 1.6 m/s²
8 0
3 years ago
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