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
Setler [38]
3 years ago
7

A painter on a ladder, painting the ceiling of a room comments. “It is hotter up here by the ceiling than it is down on the floo

r”. Explain why his observation is correct.
Physics
1 answer:
ira [324]3 years ago
4 0

Answer:

1. Hot air is less dense and has moved upward allowing cool air to move downward which is less dens

(Convection current)

2. The ceiling has transferred heat to him by radiation.

Explanation:

During the day when air is heated as a result of the ceiling transferring heat to it, it becomes less dens and it gains energy, which make it lighter in weight than cooler air, this hot air moves upward allowing cooler air to move downward.

You might be interested in
A cat dozes on a stationary merry-go-round, at a radius of 4.4 m from the center of the ride. The operator turns on the ride and
monitta

Answer:

The coefficient of static friction is 0.29

Explanation:

Given that,

Radius of the merry-go-round, r = 4.4 m

The operator turns on the ride and brings it up to its proper turning rate of one complete rotation every 7.7 s.

We need to find the least coefficient of static friction between the cat and the merry-go-round that will allow the cat to stay in place, without sliding. For this the centripetal force is balanced by the frictional force.

\mu mg=\dfrac{mv^2}{r}

v is the speed of cat, v=\dfrac{2\pi r}{t}

\mu=\dfrac{4\pi^2r}{gt^2}\\\\\mu=\dfrac{4\pi^2\times 4.4}{9.8\times (7.7)^2}\\\\\mu=0.29

So, the least coefficient of static friction between the cat and the merry-go-round is 0.29.

4 0
3 years ago
A 75 kg Spider Man running at 3.0 m/s jumps onto a trash can lid that has a mass of 10kg and that is already moving in the same
QveST [7]
In order to find the final velocity of the skier and the trash can lid, we may apply the principle of conservation of momentum, which states that the total momentum of a system remains constant. Mathematically, in this case:
m₁v₁ + m₂v₂ = m₃v₃
Where m₃ and v₃ are the combined mass and velocity.

75*3 + 10*2 = (75 + 10)*v₃
v₃ = 2.88 m/s

The final velocity is 2.88 m/s
6 0
3 years ago
Read 2 more answers
How much energy or stopping power is needed to bring a car to a stop from 100 mph?
Fed [463]
I think 100 mph pushing the car the opposite direction
3 0
3 years ago
A train whistle is heard at 300 Hz as the train approaches town. The train cuts its speed in half as it nears the station, and t
spin [16.1K]

Answer:

The speed of the train before and after slowing down is 22.12 m/s and 11.06 m/s, respectively.

Explanation:

We can calculate the speed of the train using the Doppler equation:

f = f_{0}\frac{v + v_{o}}{v - v_{s}}        

Where:

f₀: is the emitted frequency

f: is the frequency heard by the observer  

v: is the speed of the sound = 343 m/s

v_{o}: is the speed of the observer = 0 (it is heard in the town)

v_{s}: is the speed of the source =?

The frequency of the train before slowing down is given by:

f_{b} = f_{0}\frac{v}{v - v_{s_{b}}}  (1)                  

Now, the frequency of the train after slowing down is:

f_{a} = f_{0}\frac{v}{v - v_{s_{a}}}   (2)  

Dividing equation (1) by (2) we have:

\frac{f_{b}}{f_{a}} = \frac{f_{0}\frac{v}{v - v_{s_{b}}}}{f_{0}\frac{v}{v - v_{s_{a}}}}

\frac{f_{b}}{f_{a}} = \frac{v - v_{s_{a}}}{v - v_{s_{b}}}   (3)  

Also, we know that the speed of the train when it is slowing down is half the initial speed so:

v_{s_{b}} = 2v_{s_{a}}     (4)

Now, by entering equation (4) into (3) we have:

\frac{f_{b}}{f_{a}} = \frac{v - v_{s_{a}}}{v - 2v_{s_{a}}}  

\frac{300 Hz}{290 Hz} = \frac{343 m/s - v_{s_{a}}}{343 m/s - 2v_{s_{a}}}

By solving the above equation for v_{s_{a}} we can find the speed of the train after slowing down:

v_{s_{a}} = 11.06 m/s

Finally, the speed of the train before slowing down is:

v_{s_{b}} = 11.06 m/s*2 = 22.12 m/s

Therefore, the speed of the train before and after slowing down is 22.12 m/s and 11.06 m/s, respectively.                        

I hope it helps you!                                                        

7 0
2 years ago
Cake batter, which is made of things such as sugar, eggs, and flour, is usually smooth and creamy.
Minchanka [31]
Heterogeneous mixture
5 0
3 years ago
Read 2 more answers
Other questions:
  • When you jump upwards, why don't you notice the Earth moving<br> downwards?
    15·1 answer
  • What is the displacement for a driver who travels 10 km to get to a point that is 4 km from his starting point?
    5·1 answer
  • A 180 cm length of string has a mass of 5.0 g. it is stretched with a tension of 8.6 n between fixed supports. (a) what is the w
    13·1 answer
  • In an experiment different wavelengths of light, all able to eject photoelectrons, shine on a freshly prepared (oxide-free) zinc
    5·1 answer
  • Suppose you are driving a car around in a circle of radius 212 ft, at a velocity which has the constant magnitude of 43 ft/s. A
    9·1 answer
  • When a person stands on a rotating merry-go-round the frictional force?
    15·1 answer
  • A gas has a volume of 1.5 L at 375 kPa.
    14·1 answer
  • A small difference between means may not be statistically significant, but it could reach statistical significance with a large
    5·1 answer
  • Pedro is planning to model how changes in weather affect evaporation from lakes for his first experiment he wants to test how hu
    5·1 answer
  • Meme on newtons law of motion (should me made ur self not from any searh engine)
    10·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!