1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
ivolga24 [154]
3 years ago
8

A cylindrical resistor element on a circuit board dissipates 1.2 W of power. The resistor is 2 cm long, and has a diameter of 0.

4 cm. Assuming heat to be transferred uniformly from all surfaces, determine (a) the amount of heat this resistor dissipates during a 24-hour period, (b) the heat flux, and (c) the fraction of heat dissipated from the top and bottom surfaces.
Physics
1 answer:
34kurt3 years ago
7 0

Answer:

(a) The resistor disspates 103680 joules during a 24-hour period.

(b) The heat flux of the resistor is approximately 4340.589 watts per square meter.

(c) The fraction of heat dissipated from the top and bottom surfaces is 0.045.

Explanation:

(a) The amount of heat dissipated (Q), measured in joules, by the cylindrical resistor is the power multiplied by operation time (\Delta t), measured in hours. That is:

Q = \dot Q \cdot \Delta t (1)

If we know that \dot Q = 1.2\,W and \Delta t = 86400\,s, then the amount of heat dissipated by the resistor is:

Q = (1.2\,W)\cdot (86400\,s)

Q = 103680\,J

The resistor disspates 103680 joules during a 24-hour period.

(b) The heat flux (Q'), measured in watts per square meter, is the heat transfer rate divided by the area of the cylinder (A), measured in square meters:

Q' = \frac{\dot Q}{A} (2)

Q' = \frac{\dot Q}{\frac{\pi}{2}\cdot D^{2}+\pi\cdot D \cdot h } (3)

Where:

D - Diameter, measured in meters.

h - Length, measured in meters.

If we know that \dot Q = 1.2\,W, D = 4\times 10^{-3}\,m and h = 2\times 10^{-2}\,m, the heat flux of the resistor is:

Q' = \frac{1.2\,W}{\frac{\pi}{2}\cdot (4\times 10^{-3}\,m)^{2}+\pi\cdot (4\times 10^{-3}\,m)\cdot (2\times 10^{-2}\,m) }

Q' \approx 4340.589\,\frac{W}{m^{2}}

The heat flux of the resistor is approximately 4340.589 watts per square meter.

(c) Since heat is uniformly transfered, then the fraction of heat dissipated from the top and bottom surfaces (r), no unit, is the ratio of the top and bottom surfaces to total surface:

r = \frac{\frac{\pi}{2}\cdot D^{2}}{A} (3)

If we know that A \approx 2.765\times 10^{-4}\,m^{2} and D = 4\times 10^{-3}\,m, then the fraction is:

r = \frac{\frac{\pi}{2}\cdot (4\times 10^{-3}\,m)^{2} }{2.765\times 10^{-4}\,m^{2}}

r = 0.045

The fraction of heat dissipated from the top and bottom surfaces is 0.045.

You might be interested in
A chunk of ice with a mass of 1.2 kg melts and absorbs 3.33 x 10³J of energy. Which best describes what has happened in this sys
Maurinko [17]

Answer:

- Its entropy increases.

Explanation:

Entropy is defined as a 'measure of the amount of energy in a physical system that cannot be used to do work.' It is also employed to denote randomness, disorder, or uncertainty of the arrangement/system. In the given system, the melting of ice denotes the 'increase in entropy' as the amount of energy unavailable to do work increases('absorbs 3.33 x 10³J of energy'). Thus, <u>this signifies that the entropy increases with a rise in temperature as it allows the substance to have greater kinetic energy</u>.

3 0
3 years ago
In an atomic clock there are approximately 9.193 × 109oscillations of the specified light emitted by cesium-133 atoms. The text
Aleks [24]

Explanation:

6000 years = 6000 x 365 x 24 x 60 x 60

= 1.892 x 10¹¹ second

 gain is 1 second

1 second is equivalent to 9.193 × 10⁹ oscillations .

In 1.892 x 10¹¹ second ,  change in oscillation is 9.193 × 10⁹ oscillation

in one second change in oscillation = (9.193 / 1.892 ) x 10⁹⁻¹¹

=  4.859 x 10⁻² oscillations .

5 0
3 years ago
Christina drives his moped 7 kilometers North. She stops for lunch and then drives 5 kilometers East. What distance did she cove
Mashutka [201]

Answer:

She covers the distance is 12 km.

The magnitude of displacement is 8.6 km.

The direction of her displacement is north east.

Explanation:

Given that,

Christina drives his moped 7 kilometers North and stop for lunch and then drive 5 km east.

We need to calculate the total distance

Using formula of distance

d=d_{1}+d_{2}

Put the value into the formula

d=7+5

d=12\ km

We need to calculate the magnitude of displacement

Using formula of displacement

D=xi+yj

D=5i+7j

D=\sqrt{5^2+7^2}

D= 8.6\ km

The direction of her displacement is north east.

Hence, She covers the distance is 12 km.

The magnitude of displacement is 8.6 km.

The direction of her displacement is north east.

6 0
3 years ago
1. Boyle's law relates the pressure of a gas to its
KIM [24]

Answer:

volume is the correct answer

Explanation:

7 0
2 years ago
If you are in an elevator that speed up then the apparent weight is
Sholpan [36]

Answer:

Fnet - Fg

Explanation:

When an object is in an elevator, its weight varies with respect to the direction of movement of the elevator and the elevators acceleration.

The weight, W, of an object can be expressed as;

W = mg

where m is the object's mass, and g is the acceleration due gravity.

If the object is in an elevator that speed up, an apparent weight would be felt since both mass and elevator are moving against gravitational pull of the earth.

So that,

W_{net} = mg + ma

where: mg is the weight of the object, and ma is the apparent weight.

Apparent weight (ma) = W_{net} - mg

3 0
3 years ago
Other questions:
  • Susan works 8 hours a day and makes $7.00 per hour. How much money does Susan earn in one week if she
    7·2 answers
  • Explain how kinetic energy transforms into potential energy. Give at least 2 examples.
    7·1 answer
  • My questions are in the picture: <br>Please help.
    7·1 answer
  • How many coulombs pass through a wire that carries a current of 3.2 A for 5.0 h?
    9·1 answer
  • List the number of atoms for each element in this compound: \( NH_{3} \)
    12·1 answer
  • A bowling bowl is thrown off the top of a building. Determine distance the ball has fallen after falling for 3.0 s. Remember, th
    6·1 answer
  • What is the formula for average velocity?
    12·1 answer
  • Acceleration is a change in speed or direction over time. In what two ways does the sled accelerate as it descends?
    10·1 answer
  • Help me for a physics project please
    5·1 answer
  • Exercises
    9·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!