(a) a thin layer of vacuum is provided between the two walls of flask, to minimise the heat loss by conduction , because for conduction medium (molecules) is required , but now medium is absent .
.(b) the two walls are silvered to minimise the heat loss by radiation , because a shiny surface is a bad absorber and bad emitter of radiation i.e. good reflector of heat , so prevents the heat exchange between content of flask and surrounding .
(c) the lid of flask is provided with a tight cork stopper to minimise the heat loss by convection , so that convection currents cannot go out .
(d) a plastic (or metal) case is provided with a flask , to protect the flask from physical damage
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a physical quantity is defined as mass per uint volume .what is its si unit.
What is the speed of a person travelling 30 meters in 5 seconds?
Answer:
[tex]6\:\mathrm{m/s}[/tex]
Explanation:
Denote average speed by [tex]S=\frac{d}{t}[/tex] where [tex]d[/tex] is total distance travelled and [tex]t[/tex] is time.
Plugging in given values, we get:
[tex]S=\frac{30}{5}=\fbox{$6\:\mathrm{m/s}$}[/tex].
Answer:
s
Explanation:
aluminum has a density of 270 kg/m3. what volume of aluminum would have a mass of 49.9 kg?
(unit = m^3)
0.184[tex]m^{3}[/tex] is the answer for Acellus students!
A wave that can travel through empty space?
A. electromagnetic wave
B. mechanical wave
C. compressional wave
D. transverse wave
Answer: B. Mechanical Waves
Explanation:
A combination of the skill-related fitness components can determine one's
Please select the best answer from the choices provided.
True or false
A 30 kg dog runs at a speed of 15
What is the dog's kinetic energy?
6th grade science!!!!!!!!!!
Answer:
D. All of the above
Explanation:
Global warming may cause all of the given choices.
Global warming is the rise in surface temperature. This is due to the trapping of heat within the earth surface.
It is as a result of huge amount of greenhouse gases within our atmosphere. They typically permit short wave radiations to escape and they do not allow short wave radiation to pass through. This in turn produces heat.
The heat can melt polar ices and glaciers. This in turn will cause sea levels to rise. Also, the ocean temperature will generally increase due to this.Identify the state of matter.
A)The molecules are a great distance apart, moving
very rapidly, with negligible interaction. The
substance occupies all the space available.
B)The molecules are only able to vibrate rapidly about
fixed positions. The substance does not need a
container to maintain its shape.
C)The molecules move about amongst each other,
with attractive forces between them. The substance
does not necessarily fill its container
Answer:
Gases
Solids
Liquids
Explanation:
A)The molecules are a great distance apart, moving very rapidly, with negligible interaction. The substance occupies all the space available.
Gases
The state of matter described above is for gases. The distances between gases are far apart and they have very weak intermolecular attraction. They have no fixed volume as they occupy any volume of space they are introduced into.
B)The molecules are only able to vibrate rapidly about fixed positions. The substance does not need a container to maintain its shape.
Solids
Solids have fixed shape and volume. They are held together in their fixed lattice and are only able to rapidly vibrate about their fixed positions.
C)The molecules move about amongst each other, with attractive forces between them. The substance does not necessarily fill its container.
Liquids
The state of matter described here are the liquids. Liquids flow amongst each other. The attractive force between them is greater than that of gases but lesser than those of solids.
A wave has frequency of 50 Hz and a wavelength of 10 m. What is the speed of the wave? Group of answer choices
Explanation:
hehshehebdbajahwwdszsjshshs shsbw
If the base runner leaves the base before the ball is caught in the outfield, what should the defence do?
Answer:
Well it depends
Explanation:
If the runner leaves the base before
the ball is caught the defence cannot do anything exept
catch the ball if they catch the ball while he is still running he has to get back to the base before they could tag him or the base if they tag him or the base before he can get back to his base he is out if they did not catch the ball the runner can run as long as he wants just cant get taged the defence has to get the ball in as fast as possible to get the runner out.
In a normal Earth atmosphere, a feather will free fall through the air more slowly than a brick because of what force?
A. Terminal velocity
B. Momentum
C. Weightlessness
D. Air Resistance
Answer:
Air Resistance
Explanation:
Because air gives a much greater resistance to the falling motion of the feather than it does to the brick.
Select ALL of the places you might find DNA evidence.
saliva on gum
blood spatter on the wall
inside a femur bone found in the woods
cells on root of hair found at the scene
Answer:
Inside a femur bone found in the woods,
saliva of gum
The Periodic Table Question 3 of 10 Based on the trend in valence electrons across periods for main-group elements, how many valence electrons does fluorine (F) have? O A. 4 B. 7 O C. 6 D. 5 SUBT
Answer:
B. 7
Explanation:
Fluorine has 7 valence electrons in its orbitals.
The valence electrons are electrons in the outermost shell of an atom. Every element has a certain amount of valence electrons.
Fluorine belongs to the 7 - group on the periodic table. Every element in this group has 7 electrons in their outermost shell. The elements in the group are called halogens. Other elements in this group are fluorine, chlorine, bromine, iodine and astatine.Answer:
7
Explanation:
Which of the following is NOT a criteria for a celestial object to be a planet?
-The object has cleared the neighborhood around its orbit of smaller objects.
-The object is in orbit around the Sun.
-The object has a nearly spherical shape.
-The object must be massive enough have a gravitational pull on the sun.
Answer:
The option which is not a criteria for a celestial object to be a planet is;
The object must be massive enough have a gravitational pull on the Sun
Explanation:
There are three criteria for a celestial object to be classified as a planet including;
1) The object's orbit is around the Sun
2) The shape of the object is nearly round due to its mass which is capable of assuming hydrostatic equilibrium
3) Other smaller objects in the neighborhood around the object has been cleared by the object
Therefore, the option which is not a criteria for a celestial object to be a planet is that it must be massive enough to have a gravitational pull on the Sun as every two objects in the Universe share a common gravitational pull according to Newton's Law of Gravitation.
A 2-kg ball traveling eastward at 5 m/s hits a 5-kg ball moving at 1 m/s eastward. The 2-kg ball bounces west at 3.0 m/s. What is the speed of the 5kg ball?
Answer:
1.8 m/s
Explanation:
Step one:
given data
m1= 2kg
u1= 5m/s
m2= 5kg
u2= 1m/s
v1= 3m/s
From
m1u1+m2u2= m1v1+m2v2
substitute
2*5+5*1 = 2*3+5*v2
10+5= 6+5v2
15-6= 5v2
9= 5v2
divide both side by 5
v2= 9/5
v2= 1.8 m/s
Please help i don't get it.
Which image matches the Topographic Map Shown?
Also, please explain how your answer is the correct answer. Why is your answer correct?
Answer:
the answer is 4
Explanation:
the picture matches eachother that's why I picked 4
Answer:
devils tower
Explanation:
on the topographic map the circular lines stop at at certain point because the moutain doesnt get any pointyer if you know what that means
in other words if the map continued with the circular lines all the way to the centerit would have been that snowny mountain
Find the work done by a man who is pulling a box of 45kg of mass by means of rope which makes angle of 45 degrees.
Answer:
0
Explanation:
Since no distance is given, the force is not doing any work
No work is done by the man since we do not know the distance or displacement.
Work is only said to be done when the force applied on an object moves it through a particular distance.
Work done = Force x distance.
Since no distance is given in this problem, we can as well assume that the force applied is doing no work on the object.
Which idea did Ptolemy's model use to explain why the planets appeared to move backward as they moved in their orbits? The planets spun in epicycles. The planets rotated on their axes. The planets revolved around the Sun. The planets were made of different materials.
Answer:
The planets spun in epicycles.
Explanation:
The planets were not simply attached to a mystical sphere (“deferent”) but they were actually attached to a mini-sphere (“epicycle”) which rotated on the larger one.
Answer:A
Explanation:
An object moving at a constant velocity accelerates at a constant rate of 2.5 m/s2 for a distance of 30 m. At the end of the acceleration the object has a velocity of 90 m/s. What was its velocity before accelerating?
Answer:
The initial velocity is 89.16m/s
Attached is the solution
Explanation:
A box weighs 1300 N. When a horizontal force of 390 N has applied the box accelerates at 1.3 m/s2. What is the magnitude of the frictional force?
Answer:
Ffriction = 217.7[N]
Explanation:
First, we must find the mass of the box, we must remember that the weight is defined as the product of the mass by acceleration.
[tex]w=m*g[/tex]
where:
w = weight [N] (units of Newtons)
m = mass [kg]
g = gravity acceleration = 9.81 [m/s²]
[tex]1300=m*9.81\\m=132.51[kg][/tex]
Now we must use Newton's second law, which tells us that the sum of forces is equal to the product of mass by acceleration.
∑F = m*a
where:
∑F sum of forces
m = mass = 132.51[kg]
a = acceleration = 1.3[m/s²]
We must know that the forces that act are the horizontal force that moves the box and the friction force in the negative direction that acts against the movement.
Now replacing:
[tex]390-f_{friction}=132.51*1.3\\390-172.26=f_{friction}\\f_{friction}=217.7[N][/tex]
Does someone have hamster name recommendation (girl hamster)
Explanation:
Lola
Or Jasmine
Or lucy
Or Nightingale
Or Sugarcane
Or Polly
Or Heather
Some names I like!
1. A person riding a bicycle on level ground reaches a velocity of 13.4 m/s before
stopping. While braking, the internal energy of the brakes, wheels, and road
increase by 5836 J. What is the mass of the cyclist?
A solution is...
A. a mixture of two or more substances of the same state
B. a mixture of two or more substances. It is heterogeneous at the molecular level
C. a mixture of two or more substances. It is homogeneous at the molecular level
D. a mixture of two or more substances, one of which is water.
Answer:
C. a mixture of two or more substances. It is homogeneous at the molecular level
A body with mass 2 kg absorbs heat 418.4J when its temperature raises from 293K to 343K . What is the specific heat of the body?
Answer:
C M (change in T) = heat absorbed thermal equation for heat gained
C = 418.4 J / (2 kg * 50 deg K) = 4.184 J / kg * deg K specific heat
Note: 1 gm =.001 kg
So C = .004184J / gm * deg K
Also, 1 J = .239 cal so in conventional terms
C = .001 cal / gm deg K (very low, water would be 1 cal / gm deg C
From what Tim explains in the movie, what can you infer about the temperature inside a refrigerator?
Answer:
It's closest to 3 degrees celsius
Explanation:
Can anyone prove ADIABATIC PROCESS ???
Answer:
The adiabatic process can be derived from the first law of thermodynamics relating to the change in internal energy dU to the work dW done by the system and the heat dQ added to it. The word done dW for the change in volume V by dV is given as PdV. Hence, the equation is true for an adiabatic process in an ideal gas.
Explanation:
Hope it helps......bro
Janet jumps off a high diving platform with
a horizontal velocity of 2.6 m/s and lands in
the water 1.5 s later.
How far from the base of the platform
does she land? The acceleration of gravity
is 9.8 m/s?
Answer in units of m.
Answer:
11.025m
Explanation:
In this question there is no vertical velocity,
t= 1.5s
Height of platform=h
From Newton equation
s = ut + 1/2gt^2
But there is no vertical velocity,
Hence,
Then u=0
h = 0 + 1/2 x 9.8 x (1.5)^2
h = 11.025m
Temperature
Energy Input
The three states of matter are modeled in the heatind cu
curve seen here. Identify ALL of the changes that must take place for a
substance to change state, from a solid to a gas.
A)
Pressure increases
B)
Temperature increases
19
7
Particles spread apart
D)
Kinetic energy increases
E)
Particle motion increases
Answer:
Particles spread apart, temperatue increases, pressure increases
Explanation:
1) Which of the following is not a type of energy?
A: Thermal
B: Potential
C: Kinetic
D: Frictional
Please help me this is worth allot
