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
lara [203]
4 years ago
9

A solid cube of edge length r, a solid sphere of radius r, and a solid hemisphere of radius r, all made of the same material, ar

e maintained at temperature 300 K in an environment at temperature 350 K. Rank the objects according to the net rate at which thermal radiation is exchanged with the environment, greatest first.
Physics
1 answer:
juin [17]4 years ago
8 0

Answer:

Explanation:

The rate at which heat will be radiated is given by the expression

E = e Aσ ( T⁴ - T₀⁴ )

E is heat radiated , e is emissivity , A is area of surface , σ  is stephan's constant T is temperature of the object and T₀ is temperature of the surrounding .

For all the objects given , e , σ T and T₀ are same so E will solely dependent on area of the surface

surface area of cube= 6 r² ,

surface area of sphere = 4 π r²

= 12.56 r²

hemisphere = 2 π r²

= 6.28 r²

12.56 r² >6.28 r² > 6 r²

heat radiated by sphere > heat radiated by hemisphere > heat radiated by cube .

You might be interested in
Use the graph to determine the velocity of the object.
alina1380 [7]

Use the graph to determine the velocity of the object.


What is the instantaneous velocity of the object at 3 seconds?

⇒ 3 m/s


What is the average velocity of the object?


⇒ 0 m/s

6 0
3 years ago
Read 2 more answers
What wind turbines to hydroelectric dams and ethanol plants have in common?
Brut [27]

All three are forms of renewable energy.

Wind turbines utilize the wind to generate power, hydroelectric dams also do the same (although most states have stopped using them since they're bad for the environment)

Ethanol, a substitute for gasoline, comes from corn, which can be grown in farms throughout America.

8 0
3 years ago
In the dangerous "sport" of bungee-jumping, a daring student jumps from a balloon with a specially designed elastic cord attache
EastWind [94]

Answer:

k = 1755 N/m

Explanation:

Given:

- The length of the cord L = 23.4 m

- Weight of the student W = 818 N

- The elevation of balloon H = 31.3 m

Find:

Calculate the required force constant of the cord if the student is to stop safely 2.74 m above the river.

Solution:

- We know the potential energy of the student changes by  

                      ΔP.E = m*g*( H - 2.74 )

                      mg*(31.3 - 2.74) = 818*28.56 = 23362.08 J

- When he stops at 2.74 m above ground his KE = 0 so ALL his lost potential energy must be stored in the extended or stretched bungee cord.

- He falls 23.4 m before the bungee cord starts to stretch. That means it doesn't start stretching until he is 31.3 - 23.4 = 7.9 m above the ground.  

- It has to stop  stretching at 2.74 m above the ground so the

                                total stretch = 7.9 - 2.74 = 5.16 m

- Therefore his PE from 31.3 m to 2.74 m is stored in a 5.16 m stretch of the bungee cord.                      

                                ½kx² =  ΔP.E

                                k = 2*ΔP.E / x^2

                                k = 2*23362.08 / 5.16^2

                                k = 1755 N/m

3 0
3 years ago
A 3kg box is pulled along the floor with a force of P=20 N at an angle of 30 degrees. If the box is moving at a constant velocit
Deffense [45]

If force is applied at 30 degree with the horizontal

then first we will find the components of force in two directions

F_x = 20 cos20

F_y = 20 sin30

now we can find normal force by balancing the forces in Y direction

F_n + Fy = mg

F_n + 20 sin30 = 3*10

F_n + 10 = 30

F_n = 20 N

now since block is moving with constant speed

so here forces along horizontal plane will be balanced also

F_x = F_f

F_f = 20 cos30

F_f = 17.3 N

Now the weight of the box is defined as

W = mg

now plug in all values

W = 3*10 = 30 N

7 0
3 years ago
When you are driving on a rural road, if your right wheels run off the pavement, you should hold the steering wheel firmly and
julia-pushkina [17]

Answer:

C). Take your foot off the gas pedal. Then brake lightly until you are moving at low speed.                    

Explanation:

While driving on roads of rural areas, if our right wheel moves off the pavement, we should always hold the steering wheel firmly and then take our foot off the gas pedal, then apply brake lightly until we are moving at a low speed.

      When our wheels drift off the pavement area, we should not panic and yank. And instead of turning the wheel back in the left direction towards the road, it is always safer to take off our foot from the gas pedal and then apply brakes slowly. When our vehicle slows down check the incoming traffic behind us and then we should slowly move back on to the pavement.

7 0
4 years ago
Other questions:
  • Which resistors in the circuit must have the same amount of energy per unit charge across them?
    12·2 answers
  • All atoms of the same element must have the same number of
    11·2 answers
  • Maria designs a test to see if lemon trees that receive more water produce larger lemons.
    15·1 answer
  • 7. What type of mineral can scratch glass, but cannot scratch steel?
    12·1 answer
  • A typical tire for a compact car is 22 inches in diameter. If the car is traveling at a speed of 60 mi/hr, find the number of re
    12·1 answer
  • A star that is several thousand times brighter than the sun with a temperature lower than 4,000 K would be classified as — A a m
    6·1 answer
  • Why did scientists agree to use one system of measurement
    11·2 answers
  • In 1600, Dr. William Gilbert coined the term “electrica,” a word that gave rise to our word electricity.
    6·1 answer
  • How fast is a 950 kg car traveling if it has 3,800 Joules of energy
    11·1 answer
  • Give 5 examples of inherited variation
    8·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!