Answer:
A -500J
Explanation:
because W=Fs
100 × 5 = 500
The work done by friction is 500 J.
What is friction?
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other.There are several types of friction:
Dry friction is a force that opposes the relative lateral motion of two solid surfaces in contact. Dry friction is subdivided into static friction ("stiction") between non-moving surfaces, and kinetic friction between moving surfaces. With the exception of atomic or molecular friction, dry friction generally arises from the interaction of surface features, known as asperities
Fluid friction describes the friction between layers of a viscous fluid that are moving relative to each other.
Lubricated friction is a case of fluid friction where a lubricant fluid separates two solid surfaces.Skin friction is a component of drag, the force resisting the motion of a fluid across the surface of a body.
Internal friction is the force resisting motion between the elements making up a solid material while it undergoes deformation.
When surfaces in contact move relative to each other, the friction between the two surfaces converts kinetic energy into thermal energy (that is, it converts work to heat).
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the ratio of the energy per second radiated by the filament of a lamp at 250k to that radiated at 2000k, assuming the filament is a blackbody radiator? The filament of a particular electric lamp can be considered as a 90%blackbody radiator. calculate the energy per second radiated when its temperature is 2000k if its surface area is 10∧-6 m²
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
"" damped force equation ""
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.
pls someone should help me answer question 3. Thank you
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
M^3 is a derived unit why?
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
A HIGH SPEED TRAIN IS 180M LONG AND IT IS TRAVELLING AT 50M/S.HOW LONG WILL IT TAKE TO PASS A PERSON STANDING AT A LEVEL CROSSING?
B-HOW LONG WILL IT TAKE TO PASS COMPLETELY THROUGH A STATION WHOSE PLATFORMS ARE 220M IN LENGTH?
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
A car travels first 30 km at a uniform speed of 20 km
/hr and went 30 km at a uniform speed of 40 km/hr
Find its average speed in km/hr
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
Find the emitted power per square meter and wavelength of peak intensity for a 3000 K object that emits thermal radiation.
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
calculate the voltage applied to 2.00
Answer:
Here is your answer
Explanation:
1.55 V is the answer
hope u like it
a student drops a ball off the top of building and records that the ball takes 3.32s to reach the ground (g=9.8 m/s^2). what is the ball's speed just before hitting the ground?
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).
b) A stone floor feels very cold to bare feet in winter, but a carpet in
the same room feels comfortably warm. Why is this?
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.
skater with a mass of 50.0 kg slides across an icy
pond with negligible friction. As he approaches a
friend, both he and his friend hold out their hands,
and the friend exerts a force in the direction oppo-
site to the skater's movement, which slows the skat-
er's speed from 2.0 m/s to 1.0 m/s. What is the
change in the skater's kinetic energy?
A. –25 J
C. – 100J
B. -75J
D. -150J
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.
IV. The table below shows how the speed of a car changes with time. 1 What is the acceleration of the car? please help! :(
The circuit diagram below shows the locations of four switches. Which
switch configuration creates a short circuit?
fo
W
WT
Answer:
C option
Explanation:
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The density of oil is 0.8 g/cm^3. What is the mass of 36 cm^3 of oil? + (1 Point) O 0.29 N O 28.09 28.8 g O 36.89
Answer:
density = mass/volume
density=0.8
volume=36
mass=?
0.8=mass/36
mass = 36x0.8=28.8g
A small bar magnet is placed in the magnetic field of a larger
bar magnet, at the position marked Zin the diagram below.
Assuming the small bar magnet is free to rotate, how would it
be positioned?
X
no
N
S
O A.
N.
B.
N
s
O c.
S
O D.
S
x for a smaller magnet at the position marked zin
Señalar la importancia de las capacidades fisico-motiz que se desarrollan en el futbol de salon y dar un ejemplo para cada uno
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.
1. The electromagnetic spectrum is the range of all types of radiation.
a. index of refraction
b. EM
c. laser
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
Accelaration is a derived quantity .Give reason
Answer:
The accerlation is a derived from the other quantities like change in velocity/time take etc.
A 4 mm object is observed by a magnifying lens as 1.25 cm. Calculate the ratio do/di.
Answer:
dₒ/dᵢ = 0.32
Explanation:
From the question given above, the following data were obtained:
Object height (Hₒ) = 4 mm
Image height (Hᵢ) = 1.25 cm
Ratio of object distance (dₒ) to image distance (dᵢ) [dₒ/dᵢ] =?
Next, we shall convert 4 mm to cm. This can be obtained as follow:
10 mm = 1 cm
Therefore,
4 mm = 4 mm × 1 cm / 10 mm
4 mm = 0.4 cm
Next, we shall determine the magnification of the lens. This can be obtained as follow:
Object height (Hₒ) = 4 mm
Image height (Hᵢ) = 1.25 cm
Magnification (M ) =?
M = Hᵢ/Hₒ
M = 1.25 / 0.4
M = 3.125
Finally, we shall determine the ratio of object distance (dₒ) to image distance (dᵢ). This can be obtained as follow:
Magnification (M) = 3.125
Ratio of object distance (dₒ) to image distance (dᵢ) [dₒ/dᵢ] =?
Magnification (M) = image distance (dᵢ) / object distance (dₒ)
M = dᵢ/dₒ
Invert
1/M = dₒ/dᵢ
1/3.125 = dₒ/dᵢ
dₒ/dᵢ = 0.32
Therefore, the ratio of object distance (dₒ) to image distance (dᵢ) [dₒ/dᵢ] is 0.32
Um comentarista de futebol certa vez comentou:"A bola bateu na trave e voltou duas vezes mais forte". Sabendo que quando a bola atinge a trave ela acerta com uma força chamada de ação e a outra trave acerta com outra força chamada de reação explique porque a frase documentalista soa errada.
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:
A bus travels with a constant speed of 48km/h. How long will it take to travel 60km?
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
what is meant by fundamental unit? write any two difference between mass and weight.
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
Differentiate between a derived quantity and a derived unit.
Explanation:
Derived quantities are quantities dependent on fundamental quantities while derived units are the units of these quantities
A car travelling at 30 ms' decelerates
to 10 m sin a distance of 20 m. What
is the deceleration of the motion, in m
s?
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.
What is resistance? Difference between resistance and resistivity.
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.
A car starts from rest. if rhe final velocity becomes 50m /s after 10 second calculate the acceleration of the car.
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
Which statement about momentum is false? a. Momentum is a force b. Momentum may be transferred c. Momentum is always conserved d. Momentum is a property only of moving objects
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.
A cheetah runs at a speed of 27.6 m/s. If the
cheetah runs for 9.30 s, what is the distance the
cheetah runs? Show all your work.
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
What is speed?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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Which instrument changes kinetic energy into electrical energy?
electric motor
hair drier
electric bell
dynamo
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.
An airplane with constant speed 696 mph than another 40 minutes constant speed 804 mph what is distance it go?
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
