Answer:
(a) [tex]\frac{P_{250k}}{P_{2000k}}=2.4\ x\ 10^{-4}[/tex]
(b) P = 0.816 Watt
Explanation:
(a)
The power radiated from a black body is given by Stefan Boltzman Law:
[tex]P = \sigma AT^4[/tex]
where,
P = Energy Radiated per Second = ?
σ = stefan boltzman constant = 5.67 x 10⁻⁸ W/m².K⁴
T = Absolute Temperature
So the ratio of power at 250 K to the power at 2000 K is given as:
[tex]\frac{P_{250k}}{P_{2000k}}=\frac{\sigma A(250)^4}{\sigma A(2000)^4}\\\\\frac{P_{250k}}{P_{2000k}}=2.4\ x\ 10^{-4}[/tex]
(b)
Now, for 90% radiator blackbody at 2000 K:
[tex]P = (0.9)(5.67\ x\ 10^{-8}\ W/m^2.K^4)(1\ x\ 10^{-6}\ m^2)(2000\ K)^4[/tex]
P = 0.816 Watt
calculate:An elcetric lamp is rated 240V and 40W. What is the cost of running the lamp for 62 hours if the elctricity authorities charges #2.50k per KWH
Explanation:
The voltage of the lamp, V = 240 V
Power of the lamp, P = 40 W
It is running for 62 hours.
The cost of running is $2.50k per KWH
Electric power is,
P = 40×62 Wh
= 2480 Wh
P = 2.48 kWh
At the rate of $2.5 per kWh
P = $6.2
So, the cost of running is $6.2 per kWh.
A exerted by an object on another is a force
hope this helps
Answer:
If a person is pushing a desk across the room, then there is an applied force acting upon the object. The applied force is the force exerted on the desk by the person.
Find the acceleration a body whose velocity increases from 11m/s to 33m/s in 10 seconds
Answer:
I am not sure if this is the answer
acceleration: 2.2m/s
Explanation:
here
initial velocity(u): 11m/s
Final velocity(v): 33m/s
time taken(t): 10 s
now
a:v-u/t
or
acceleration:final velocity-initial velocity/time taken
or
a: 33-11/10
or
a:22/10, divide it
: a=2.2m/s#
The initial momentum of a system is measured at 300 kg•m/s. Afterwards, the
momentum is measured to be 280 kg•m/s. What is the impulse of the system?
A woman pushes a car with a force of 400 N for a distance of 15m. How much work has she done?
Answer:
the work done by the woman is 6,000 J
Explanation:
Given;
force applied by the woman, F = 400 N
distance moved by the woman, d = 15 m
The work done by the woman is calculated as follows;
W = F x d
W = 400 N x 15 m
W = 6000 Nm = 6,000 J
Therefore, the work done by the woman is 6,000 J
1o4 Fahrenheit is equal to
Answer:
40 degrees Celsius
Explanation:
Have a great summer :)
A force of 20000N acts on the raft in the direction down
State the name given to the force shown by arrow in Fig.
Calculate the mass of the raft.
Answer:
Figure is not there
Explanation:
WILL MARK BRAINLIEST
Answer:
152,155 J
Explanation:
115,333 + 36,822 = 152,155J
True or false please help I’ll give brainliest
Answer:
1 is false 2 is true 3 is false
Temperature of substance changes from -20 celsius to 20 celsius. What is temperature change in kelvin scale
Answer:
313kelvin
Explanation:
40 degree celcius plus 273=313K
If the car falls down the side of the cliff, what is happening to the gravitational potential energy of the falling car (Assume the bottom of the cliff is zero)
Group of answer choices
the gravitational potential energy is decreasing
the gravitational potential energy has not changed
the gravitational potential energy is increasing
Explanation:
Gravitational potential energy is energy an object possesses because of its position in a gravitational field. ... The gravitational potential energy is equal to its weight times the height to which it is lifted. PE = kg x 9.8 m/s2 x m = joules. The 9.8 us the gravitational acceleration constant.
so the answer is "the gravitational potential energy is decreasing"
B
oc
OD
A metal has a specific heat capacity of 360J/(kg°C).
An object made of this metal has a mass of 2.0kg.
What is the thermal capacity (heat capacity) of the object?
Answer:
Thermal capacity of the object = 720 j/°C
Explanation:
Given:
Specific heat capacity of metal = 360J/(kg°C)
Mass of given object = 2 kg
Find:
Thermal capacity of the object
Computation:
Thermal capacity = Specific heat x Mass
Thermal capacity of the object = Specific heat capacity of metal x Mass of given object
Thermal capacity of the object = 360 x 2
Thermal capacity of the object = 720 j/°C
when a metal ball is heated through 30°c,it volume becomes 1.0018cm^3 if the linear expansivity of the material of the ball is 2.0×10^-5k^-1, calculate its original volume
Mr. Tolman believes that our universe is expanding, but with all of the gravitational force from the celestial bodies of space, the universe will begin to contract. He believes in the _____.
A) oscillating universe theory
B) inflation theory
C) steady state theory
D) big bang theory
Which two forms of electromagnetic energy are used to produce the
most spectacular fluorescence when placed in darkness?
1. microwaves and x rays
2. microwaves and infrared
3. ultraviolet and x rays
4. ultraviolet and infrared
Answer:
3. ultraviolet and x rays
The two forms of electromagnetic energy are used to produce the most spectacular fluorescence when placed in darkness are ultraviolet and x rays.
What is electromagnetic energy?Electromagnetic radiation is waves of the electromagnetic field, propagating through space, carrying electromagnetic radiant energy. It includes radio waves, microwaves, infrared, light, ultraviolet, X-rays, and gamma rays.
What is fluorescence?
Fluorescence is the process in which a substance absorbs light at a high energy, short wavelength and emits light at a lower energy, usually visible wavelength.
What is ultraviolet rays?Ultraviolet rays is a type of electromagnetic waves in which the wavelength is shorter than visible rays. It is responsible for 10% of sunlight and causes sun tan. It is used to purify water in water purifiers. It kill germs.
What is x rays?X rays lies beyond ultraviolet rays. It is used to diagnose in medical field. It can destroy living tissues so excessive exposure should be limited to reduce harmful effect.
The color change of fluorescent minerals is most spectacular when the minerals are placed in darkness and exposed to electromagnetic energy shorter than visible light.
Ultraviolet and x rays are shorter than visible light so they exhibit fluorescent property.
To learn more about Electromagnetic radiation here
https://brainly.com/question/10759891
#SPJ2
.If a vehicle covers 3 km in 5 minutes, calculate the speed of the vehicle? (With process )
Answer:
Speed = 1.6 m/s
Explanation:
Formula,
Speed = Distance ÷ Time
Two friends are working out together using weights:
-James lifts 20kg weights up at a velocity of 1.9m/s
-Kayla lifts 15kg weights up at a velocity of 2.6m/s
0
Which friend is creating more momentum?
Answer:
Kayla. You can calculate it using the formula for momentum: momentum=mass×velocity and find the bigger number between the two momentums
A fixed mass of gas has a volume of gas of 25cm3. the pressure of the gas is 100kPA. the volume of the gas is slowly decreased by 15cm3 at a constant temperature. what is the change in the pressure of the gas?
a) 67kPA
b) 150kPA
c) 170kPA
d) 250kPA
give reasons
A fixed mass of gas has a volume of 25 [tex]cm^3[/tex], the pressure of the gas is 100 kPa, the volume of the gas is slowly decreased by 15 [tex]cm^3[/tex] at a constant temperature, and the change in pressure of the gas is 150 kPa, which is option b.
What is the calculation of the change in pressure?PV = nRT (P= pressure of the gas, V =volume, n = number of moles of gas, R = gas constant, and T =temperature of the gas in kelvin)
Suppose the gas is an ideal gas and that the temperature is constant,
P1V1 = P2V2
Here P1 = 100 kPa, V1 = 25 [tex]cm^3[/tex], V2 = 10 [tex]cm^3[/tex],
100 kPa x 25 [tex]cm^3[/tex] = P2 x 10 [tex]cm^3[/tex]
P2 = (100 kPa x 25 [tex]cm^3[/tex]) / 10 [tex]cm^3[/tex]
P2 = 250 kPa
the change in pressure of the gas is,
ΔP = P2 - P1 = 250 kPa - 100 kPa = 150 kPa
The reason is that when the volume of a fixed mass of gas is decreased, the pressure of the gas increases proportionally, so here assuming that the temperature is constant it is calculated.
Hence, the volume of the gas is slowly decreased by 15 [tex]cm^3[/tex] at a constant temperature, and the change in pressure of the gas is 150 kPa, which is option b.
Learn more about the calculation of the change in pressure here.
https://brainly.com/question/15938504
#SPJ1
What are the poles of a bar magnet.is it North West South or east.
Answer:
One end of any bar magnet will always want to point north if it is freely suspended. This is called the north-seeking pole of the magnet, or simply the north pole. The opposite end is called the south pole.
Explanation:
Answer:
North Pole and South Poles
Explanation:
There is no east or west in a magnetic field of a magnet. The magnetic field lines comes from North pole to south pole.
VI. A student attaches four drawing pins to a copper rod using candle wax as shown in the diagram
The rod is then heated continuously at one end and the pins fall off in the order 4, 3, 2, 1
Explanation:
[tex]C.) \: Conduction \: \\ \\ = > it \: is \: a \: process \: of \: transferring \: \\ \\ of \: heat \: from \: one \: object \: to \: another \\ \\ when \: they \: are \: in \: contact \: [/tex]
By the conduction process the heat reaches the pin.Option C is correct.
What is heat transfer?The term "heat transfer" refers to the movement of heat. The flow of heat across a system's boundary is due to a temperature differential between the system and its surroundings.
Conduction is the type of heat transfer occurs mainly in solid or by contact.In the given condition the rod is then heated continuously at one end and the pins fall off in the order 4, 3, 2, 1.
By the conduction process the heat reaches the pin.
Hence option C is correct.
To learn more about the heat transfer refer to the link;
https://brainly.com/question/13433948
#SPJ2
A 1500 kg truck travelling north at 60 km/hr collides with a 1200 kg car moving east at 15km/hr. If the two cars remain locked together after impact, with what velocity do they move immediately after the collision.
Answer:
33.33j+6.67i km/hr
Explanation:
From the law of conservation of momentum,
Applying,
mu+m'u' = V(m+m')............... Equation 1
Where m = mass of the truck, m' = mass of the car, u = initial velocity of the truck, u' = initial velocity of the car, V = Final velocity.
Note: let j represent the north, and i represent the east
From the question,
Given: m = 1500 kg, u = 60j, m' = 1200 kg, u' = 15i
Substitute these values into equation 1
1500*60j+1200*15i = V(1500+1200)
90000j+18000i = 2700V
V = (90000j+18000i)/2700
V = 33.33j+6.67i km/hr
10.
You are standing on a sheet of ice that covers the football stadium parking lot in Buffalo; there is
negligible friction between your feet and the ice. A friend throws you a 0.4 kg ball that is traveling
horizontally at 10 m/s. Your mass is 70 kg. If you catch the ball, with what speed do you and the ball
move afterwards?
1.02 m/s
0.06 m/s
0.02 m/s
0.12 m/s
Answer:
Explanation:
This is a classic Law of Momentum Conservation problem. For us the equation will look like this:
[tex][(m_yv_y+m_bv_b)]_b=[(m_y+m_b)v_{both}]_a[/tex] Filling in with our given info:
[tex][(70.0)(0)+(.40)(10.0)]_b=[(70.0+.40)v_{both}]_a[/tex] and
4.0 = 70.4v and
v = .06 m/s
what is fundamental
Fundamental
forming a necessary base or core; of central importance.
"the protection of fundamental human rights"
A 500-kg crate sits on a 10-degree ramp. If friction between the ramp and the crate is 800 N, what is the acceleration of the crate?
By Newton's second law, the net force acting on the crate parallel to the surface is
∑ F = mg sin(10°) - 800 N = ma
where m = 500 kg is the mass of the crate and a is the acceleration.
Solve for a :
a = ((500 kg) (9.80 m/s^2) sin(10°) - 800 N) / (500 kg)
a ≈ 0.102 m/s^2
the acceleration of a moving vehicles is 10 metre per second square what does it means
Answer:
Acceleration is the rate of change of velocity. What is commonly said as ‘ten meter per second squared’ can bee broken down into ‘ten meter per second per second.’ This gives us the true meaning of the term acceleration.
Just like ‘ten meter per second’ means increasing the displacement by ten meters every second, ‘ten meter per second per second’ means increasing the velocity by ten meters per second every second.
So, basically if you consider the case of a free fall motion, where ‘t’ stands for time and ‘v’ stand for velocity at that instant:
At,
t=0, v=0 m/s
t=1, v=0+10 m/s;
t=2, v=0+10+10 m/s;
t=3, v=0+10+10+10 m/s;
This can also be thought as a Arithmetic Progression where common difference ‘D’ is the acceleration(a), since it adds a 10 m/s to velocity every second and the first term ‘A’ stands for the initial velocity (u). Using this approach we can derive to the first equation of motion:
v = u + at
Hope this Answer Helps!!
Explanation:
plz mark me as a brainlest and thank my answer
It means that the vehicle's speed increases at the rate of 10m/s every second.
At any time, it's speed is 10 m/s faster than it was 1 second earlier.
The switch is released and the door locks. Explain in detail how this happens.
Answer:
The iron bolt is attracted to the electromagnet. The force of attraction between the electromagnet's core and the iron bolt is greater than the force of the spring, so the iron bolt is pulled out of its housing in the door
Explanation:
which type of material is the best sound absorber?
a. glass
b. wood
c. concrete
d. carpet
Explanation:
Glass is the best sound absorber material.
Complete the equation to show the radioactive decay of carbon-14 to nitrogen-14
Answer:
The beta decay takes place.
Explanation:
The reaction of radioactivity of carbon 14 to nitrogen 14 is
There is a beta decay.
The reaction is
[tex]C_{6}^{14}\rightarrow N_{7}^{14}+\beta _{-1}^{0}+ energy[/tex]
Here some energy is released in form of neutrino.
In which of these media will mechanical waves travel the slowest in?
a Plastic
b Butter
C Ice
d Air
e Steel
Answer:
E
Explanation:
it has more mass
The medium in which mechanical waves will travel the slowest in is air which is gaseous medium.
What is mechanical wave?A mechanical wave is a type of wave that requires material medium for its propagation.
An example of mechanical wave is sound wave because sound wave requires material medium for its propagation.
Sound waves travel fastest in solid, followed by liquid, then least in gasous medium.
Thus, the medium in which mechanical waves will travel the slowest in is air which is gaseous medium.
Learn more about mechanical waves here: https://brainly.com/question/9242091
You throw a water balloon straight up with a velocity of 13 m/s. What is its
maximum height?
O A. 4.4 m
B. 6.3 m
C. 10.7 m
D. 8.6 m
Answer:
Explanation:
[tex]h=-v^2 /2g[/tex]
[tex]with\\g = 9,8 m/s^2 or 10 m/s^2[/tex]
[tex]h= (-13)^2 / 2 * 9,8 = 8,6[/tex]