Please help me find the answers!

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

Answer:

B

Explanation:

Calculate the kinetic energy before and after they hold hands. Then, to find the change in kinetic energy simply subtract the final KE by initial KE.

Answer:

256.68m

Explanation:

that is the procedure above

A cheetah runs at a speed of 27.6 m/s. If the cheetah runs for 9.30 s, then the distance covered by the cheetah would be 256.68 metes

The total distance covered by any object per unit of time is known as speed. It depends only on the magnitude of the moving object. The unit of speed is meter/second. The generally considered unit for speed is a meter per second.

The mathematical expression for speed is given by

speed = distance /Total time

As given in the problem A cheetah runs at a speed of 27.6 m/s. If the cheetah runs for 9.30 s, we have to calculate the distance covered by the cheetah

Distance=?

speed=27.6 m/s

time= 9.30 s

speed = distance /Total time

27.6 m/s = Distance /9.30 s

Distance = 27.6×9.30

               =256.68 metes

Thus, the distance covered by the cheetah would be 256.68 metes

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Answer:

20 = 30 / t1

t1 = 3/2

40 = 30 / t2

t2 = 3/4

average speed = total distance / total time taken

= 30 + 30 / 3/2 + 3/4

= 60 /9/4

= 60 × 4/9

= 26.667

Answer:

Dynamo

Explanation:

As we all know, there are dynamos in bicycles. When we paddle the cycle, the wheels of the cycle rotates by generating kinetic energy. When the wheels rotate, the dynamo starts to rotate. This makes the motor inside the dynamo rotates and generate electrical energy.

Answer:

Here is your answer

Explanation:

1.55 V is the answer

hope u like it

Answer:

A stone floor feels very cold to bare feet in winter, but a carpet in the same room feels comfortably warm.This is because both the floor and the carpet have the same temperature as both are exposed to the same atmosphere. But the former conducts away the heat from the feet better than the carpet as the latter is a non-conductor. So the feet losing more heat, the floor appears cooler to the feet

Explanation:

Hope it may help you!!

Both actually have same temperature. Our feet are warm. Floor is conductor of heat while carpet is not. When we walk on floor, then floor takes away or conducts the heat from our feet, so we feel cold. While carpet doesn't do that, so we feel warm.

Answer:

V²=U² + 2as

Where V=Final Velocity

U=Initial Velocity

a=acceleration ( Deceleration in this case)

s=distance covered

10² = 30² + 2(a)(20)

100 = 900 + 40a

100 - 900 = 40a

-800=40a

a= -800/40

a= -20ms-².

Its negative because the car Decelerated.

Answer:

536 miles

Explanation:

If the airplane is running at a speed of 804 miles per hour, and covers a distance, x in a particular number of mile. The distance in mile can be gotten they the application of direct formula. Multiplying the speed by the time it took, and thus

804 mph * 40

Remember the time is in minutes and not hours, so, you convert it to hours.

804 * 40/60 hours =

536 miles

Answer:

Fundamental unit is any unit that is not dependent on other units and other units can be derived from them

Explanation:

Units such as Kilogram, Mass and Time are said to be fundamental units because they are independent.

Differences between Mass and weight;

1. Mass is the measure of the amount of matter in a body while weight is a measure of how the force of gravity acts upon that mass.

2. Mass is a scalar quantity while weight is a vector quantity

La respuesta correcta para esta pregunta abierta es la siguiente.

A pesar de que no anexas opciones o incisos para responder, podemos comentar lo siguiente.

La importancia de las capacidades físico-motriz que se desarrollan en el futbol de salón son determinantes para desarrollar o maximizar las actividades propias de este deporte con objeto de rendir al máximo y aspirar al mejor de los resultados.

Estas capacidades físico-motrices son las que le permiten a un jugador realizar su máximo esfuerzo, mejorar su desempeño físico y conseguir resultados positivos.

Estamos hablando de la fuerza, la velocidad y la resistencia.

La velocidad es la aceleración que el jugador de futbol necesita para aumentar su velocidad de un punto A, a un punto B, en el menor tiempo posible.

La resistencia es la capacidad del jugador de futbol para mantener ese nivel de aceleración y desempeño, sin bajar su rendimiento. Su capacidad física debe ser resistente para ser constante en su rendimiento físico.

La fuerza es la potencia con la que desempeña los movimiento físicos dentro de la cancha.

Answer:

the thin steel wall because that wall is so very to fast broke

Answer:

From the base unit of length, we can define volume, and from the base units of length, mass, and time, we can define energy. ... Volume. Since volume is length cubed, its SI derived unit is m3

Explanation:

Hope it helps

Answer:

(a) 12 m/s

(b) At t = 0, x'(t) = 0

At t = 5.0 s, x'(t) = 15 m/s

At t = 10.0 s, x'(t) = 12 m/s

(c) i. The initial velocity = 2.0 cm/s

The initial position = 50 cm

The initial acceleration = 0.125 cm/s²

ii. 16 seconds

2. (a) Approximately 0.85 m/s

(b) 2.094 J

(c) i. Approximately 49.74 m/s

ii. Approximately 86.38°

3. (i) 4·i + 5·j

(ii) -2·i - j - 2·k

(iii) 5·i + 4·j - 3·z

(iv) 8

(v) (a) The magnitude is 2.8 cm, the direction is East

(b) The magnitude is ((14·√3)/5) cm, the direction is North

(c)  The magnitude is ((14·√3)/5), the direction is South

Explanation:

x(t) is given as follows;

x(t) = b·t² - c·t³

Where;

b = 2.4 m/s(²) (we note that the unit of b for the term to be distance in m/s²)

c = 0.120 m/s³

(a) At t = 0, we have;

x(0) = b × 0² - c × 0³ = 0

At t = 10.0 s, we have;

x(10.0) = 2.4 m/s² × (10.0 s)² - 0.120 m/s³ × (10.0 s)³ = 120 m

The average velocity = (Total distance)/(Total time)

∴ The average velocity of the car for the time interval t = 0 to t = 10.0 s, [tex]v_{ave}[/tex], is given as follows;

[tex]v_{ave}[/tex] = (120 m - 0 m)/(10.0 s - 0 s) = 12 m/s

The average velocity of the car for the time interval t = 0 to t = 10.0 s, [tex]v_{ave}[/tex]  = 12 m/s

(b) The instantaneous velocity, [tex]v_{inst}[/tex], is given as follows;

[tex]v_{inst} = \lim \limits_{t \to 0} \left( v_{ave}\right) = \lim \limits_{t \to 0} \left( \dfrac{\Delta x}{\Delta t} \right) = \dfrac{dx}{dt} = x'(t)[/tex]

[tex]x'(t) = \dfrac{d\left (b \cdot t^2 - c \cdot t^3\right)}{dt}[/tex]

x'(t) = 2·b·t - 3·c·t²

At t = 0, x'(t) = 2 × b × 0 - 3 × c × 0² = 0

At t = 5.0 s, x'(t) = 2 × 2.4 m/s² × 5.0 s - 3 × 0.120 m/s³ × (5.0 s)² = 15 m/s

At t = 10.0 s, x'(t) = 2 × 2.4 m/s² × 10.0 s - 3 × 0.120 m/s³ × (10.0 s)² = 12 m/s

(c) x(t) = 50 cm + (2.0 cm/s)·t - (0.0625 cm/s²)·t²

i. The initial velocity is the instantaneous velocity, x'(t), at time, t = 0

x'(t) = 2.0 cm/s - 2 × 0.0625 cm/s² × t

At t = 0, x'(0) = 2.0 cm/s - 2 × 0.0625 cm/s² × 0 = 2.0 cm/s

The initial velocity, x'(0) = 2.0 cm/s

The initial position = The position at time t = 0 = x(0)

x(0) = 50 cm + (2.0 cm/s) × 0 - (0.0625 cm/s²) × 0² = 50 cm

The initial position, x(0) = 50 cm

The initial acceleration, x''(0) = 2 × 0.0625 cm/s² = 0.125 cm/s²

ii. x'(t) = 2.0 cm/s - 2 × 0.0625 cm/s² × t

When the velocity of the turtle, x'(t) = 0 we have;

0 = 2.0 cm/s - 2 × 0.0625 cm/s² × t

∴ t = (2.0 cm/s)/(2 × 0.0625 cm/s²) = 16 seconds

The velocity of the turtle is zero after 16 seconds

2. The mass of the large fish, m₁ = 15.0-kg

The speed of the large fish, v₁ = 1.1 m/s

The mass of the smaller fish, m₂ = 4.50 kg

The speed of the small (stationary) fish, v₂ = 0

The initial momentum = 15.0 kg × 1.1 m/s + 4.50 kg × 0 = 16.5 kg·m/s

The initial momentum = 16.5 kg·m/s

The final momentum = (15.0 kg + 4.50 kg) × v₃ = 19.50 kg × v₃

The final momentum = 19.50 kg × v₃

Where;

The total initial momentum = The total final momentum

We get;

16.5 kg·m/s = 19.50 kg × v₃

∴ v₃ = (16.5 kg·m/s)/(19.50 kg)

v₃ = (16.5/19.50) m/s = (11/13) m/s ≈ 0.85 m/s

∴ The speed of the large fish just after it eats the small, v₃ ≈ 0.85 m/s

(b) The initial kinetic energy, K.E.₁ = (1/2) × 15 kg × (1.1 m/s)² = 9.075 J

The final kinetic energy, K.E.₂ = (1/2) × 19.5 kg × (11/13 m/s)² = 363/52 J

The mechanical energy dissipated, ΔE = K.E.₁ - K.E.₂

ΔE = (9.075 - 363/42) J = 1089/520 J ≈ 2.094 J

The mechanical energy dissipated, ΔE = 2.094 J

(c) i. We have the total momentum = 110 × 8.8· j + 85 × 7.2· i = 9.680·i + 612·i

The velocity after collision, v = (9.680·i + 612·i)/(110 + 85) = 49.64·j + 3.14·i

The magnitude of the velocity, v = √(49.64² + 3.14²) ≈ 49.74 m/s

ii. The direction, θ = arctan(49.64/3.14) ≈ 86.38°

3. (i) [tex]\underset{A}{\rightarrow} + \underset{B}{\rightarrow}[/tex] = (i + 2·j - k) + 3·i + 3·j + k = 4·i + 5·j

(ii) [tex]\underset{A}{\rightarrow} - \underset{B}{\rightarrow}[/tex] = (i + 2·j - k) - (3·i + 3·j + k) = -2·i - j - 2·k

(iii) [tex]\underset{A}{\rightarrow} \times \underset{B}{\rightarrow}[/tex] = (2 + 3)·i - (1 + 3)·j + (3 - 6)·z = 5·i + 4·j - 3·z

(iv) [tex]\underset{A}{\rightarrow} \cdot \underset{B}{\rightarrow}[/tex] = 1×3 + 2 × 3 + (-1)×1 = 8

(v) (a) [tex]\underset{A}{\rightarrow} + \underset{B}{\rightarrow}[/tex] = 2.8·cos(60°)·i + 2.8·sin(60°)·j + (2.8·cos(60°)·i - 2.8·sin(60°)·j

[tex]\underset{A}{\rightarrow} + \underset{B}{\rightarrow}[/tex] = 5.6·cos 60°·i = 2.8·i

The magnitude = 2.8, the direction is east

(b) [tex]\underset{A}{\rightarrow} - \underset{B}{\rightarrow}[/tex] = 2.8·cos(60°)·i + 2.8·sin(60°)·j - (2.8·cos(60°)·i - 2.8·sin(60°)·j

[tex]\underset{A}{\rightarrow} - \underset{B}{\rightarrow}[/tex] = 5.6·sin(60°)·j= ((14·√3)/5)·j

The magnitude = ((14·√3)/5), the direction is North

(c)  [tex]\underset{B}{\rightarrow} - \underset{A}{\rightarrow}[/tex] = (2.8·cos(60°)·i - 2.8·sin(60°)·j - (2.8·cos(60°)·i + 2.8·sin(60°)·j)

[tex]\underset{B}{\rightarrow} - \underset{A}{\rightarrow}[/tex] = -5.6·sin(60°)·j= (-(14·√3)/5)·j

The magnitude = ((14·√3)/5), the direction is South

Answer:

In many vibrating systems the frictional force Ff can be modeled as being proportional to the velocity v of the object: Ff = −cv, where c is called the viscous damping coefficient.

Answer:

power per square meter = 4.593 × 10^(6) W/m²

Wavelength of peak intensity = 9.67 × 10^(-7) m

Explanation:

From Stefan-Boltzmann law, total emitted power per square meter is given as;

P/A = eσT⁴

where;

P is power

A is surface area

σ = Stefan-Boltzmann constant = 5.67 × 10^(-8) W/m².k⁴

T = temperature of the body = 3000 K

e = emissivity of the substance (for ideal radiation, it has a value = 1)

Thus, Plugging in the relevant values we have;

P/A = 1 × 5.67 × 10^(-8) × (3000)^(4)

P/A = 4.593 × 10^(6) W/m²

Let's find the wavelength of peak intensity.

From wiens displacement law, we know that;

λ_m × T = b

where;

λ_m = maximum wavelength

T = Temperature

b is Wien's displacement constant = 2.9 × 10^(−3) m/K

thus;

λ_m = b/T = (2.9 × 10^(−3))/3000 = 9.67 × 10^(-7) m

Answer:

Explanation:

Use the one-dimensional equation for motion

v = v₀ + at and filling in,

v = 0 + (-9.8)(3.32) so

v = -33 m/s (negative because it is going downwards and upwards is positive).

x for a smaller magnet at the position marked zin

Answer:

Por ela ter batido na trave, não tem como voltar 2x mais forte, por que toda ação correspondente a uma reação de igual intensidade, mas que atua no sentido oposto

Explanation:

Answer:

C option

Explanation:

Hope this helps... pls vote as brainliest

Answer:

It will take 1 hr and 15 mins.

Explanation:

Let's look at the speed equation:

s=d/t

We want to find the time, and we have the speed and the distance, so we rearrange the equation. t will be on one side and s and d will be on the other side.

t=d/s

t=60km/(48km/h)

t=1.25h

Answer:

So, option(a).

Explanation:

Momentum is the measure of motion of the object.

Momentum is given by the product of mass and the velocity of the object.

(a) It is false.

(b) It is true, momentum is transferred.

(c) It is true, As the momentum of the system is conserved when no external force is applied on the system.

(d) It is true, as the momentum is associated with the velocity of the object.

Answer:5m/s² well I am not pretty sure but hope it's help

Explanation:

u=0m

final velocity ,v=50m/s

t=10s

(v-u)/t=(50-0)/10=50/10=5m/s²

Answer:

The accerlation is a derived from the other quantities like change in velocity/time take etc.

Answer:

EM

Explanation:

The index of refraction is a special property that shows how light travels through different medias. It does not concern itself with the spectrum, only what it will do to that spectrum under laboratory conditions.

Laser light is a very narrow concentrated light form. It is not the entire spectrum, but only a very small part of it.

The answer you want is EM Electromagnetic Radiation

Answer:

a. Time = 3.6 seconds

b. Time = 4.4 seconds

Explanation:

Given the following data;

Distance = 180 m

Speed = 50 m/s

a. To find the time;

Speed can be defined as distance covered per unit time. Speed is a scalar quantity and as such it has magnitude but no direction.

Mathematically, speed is given by the formula;

[tex]Speed = \frac{distance}{time}[/tex]

Making time the subject of formula, we have;

[tex]Time = \frac{distance}{speed}[/tex]

Substituting into the equation, we have;

[tex]Time = \frac{180}{50}[/tex]

Time = 3.6 seconds

b. Distance = 220 meters

Speed = 50 m/s

To find the time;

[tex]Time = \frac{distance}{speed}[/tex]

Substituting into the equation, we have;

[tex]Time = \frac{220}{50}[/tex]

Time = 4.4 seconds

Answer:

density = mass/volume

density=0.8

volume=36

mass=?

0.8=mass/36

mass = 36x0.8=28.8g

Explanation:

Derived quantities are quantities dependent on fundamental quantities while derived units are the units of these quantities

Answer:

Resistance is a measure of the opposition to current flow in an electrical circuit.All materials resist current flow to some degree. They fall into one of two broad categories: Conductors: Materials that offer very little resistance where electrons can move easily.