Answer:
A. Looking at stick shadows on the equinox.
Explanation:
He measures the circumference by placing a pole when the sun is overhead on the days of solstice. He determined the circumference by measuring the difference between Alexandria to Syene and the angle of the pole's shadow.
The equation used for the calculation of circumference is as follow
[tex]\frac{360 degrew}{7.2 degree} = \frac{Circumference of earth}{Distance from Alexandria to Syene}[/tex]
Please refer to the following link for more details
https://www.khanacademy.org/humanities/big-history-project/solar-system-and-earth/knowing-solar-system-earth/a/eratosthenes-of-cyrene
Select the correct answer.
Which quantity is a vector quantity?
ОА. .
acceleration
OB.
mass
OC.
speed
O D.
volume
Reset
Next
Answer:
acceleration is the vector quantity because it depends on particular direction and has magnitude
A constant unbalanced force is applied to an object for a period of time. What will happen to the objects acceleration?
a. It will accelerate in the direction of the net force.
b. It will accelerate opposite the direction net force.
c. There is no acceleration.
d. Not enough information to answer
Answer:
A
Explanation:
The moving object will accelerate as long as a net force is applied. If a net force is not applied, the object will continue to move at a constant speed along the same path in curved spacetime (due to gravity). If the net force continues the velocity of the object will continue to increase until nearly reaching the limit (speed of light).
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
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
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:
The drone can fly for 25 minutes before the battery needs recharging.
The power output of the battery is 65.0 W
Calculate the maximum energy stored by the battery.
Answer:
105.6 KJ
Answer
3.7/5
4
hope this will help you friend.
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).
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
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
Learn more about speed from here
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Which has greater kinetic energy, a car traveling at 40 mph or a half-as-massive car traveling at 80 mph?
a
-The 40 mph car
-The 80 mph car
-Both have the same kinetic energy
-Neither has kinetic energy
Answer:
The 80 mph car
Because the formula says 1/2 mass but for the velocity it is squared
The circuit diagram below shows the locations of four switches. Which
switch configuration creates a short circuit?
fo
W
WT
Answer:
C option
Explanation:
Hope this helps... pls vote as brainliest
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
when is the acceleration of body is positive negative and zero?
Answer:
【 In vector form , if angle between velocity vector and acceleration vector is less than 90° and greater than 0° then it is positive acceleration and if it is less than 180° and greater than 90° then it is negative acceleration. If there is no acceleration vector then it is called zero acceleration. 】
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.
IV. The table below shows how the speed of a car changes with time. 1 What is the acceleration of the car? please help! :(
Accelaration is a derived quantity .Give reason
Answer:
The accerlation is a derived from the other quantities like change in velocity/time take etc.
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
In what way is Height related to Potential Energy?
Explanation:
Lets say you have a ball in your hand, you raise your hand to just above your head. Now, when you did that you created potential energy that is ready to be released. you drop the ball and the ball bounces a few times off the ground. Now lets say you got a ladder and doubled the ball's height doubling the energy now stored in the ball, when you drop it the ball should bounce much higher after hitting the ground as a result of more energy being released.
Hope this helped.
Two tuning forks, 492 Hz and 498 Hz, are struck simultaneously. How many beats will be heard?
none
2.00 beats
4.00 beats
6.00 beats
Answer:
6 beats
If one fork beats once and another twice in the same time period
you would hear 1 beat. (Same for 2 and 3 beats).
Object A has twice the mass of object B. Both objects are moving at the same speed. Which accurately describes how inertia relates to Newton’s second law of motion in this example? Object A has twice the mass of object B. Both objects are moving at the same speed.
A. Object A requires twice the force to stop as Object B.
B. Object A requires one-and-a-half times the force to stop as Object B.
C. Object A requires four times the force to stop as Object B.
Answer:
A. Object A requires twice the force to stop as Object B.
Explanation:
Inertia can be defined as the tendency of an object or a body to continue in its state of motion or remain at rest unless acted upon by an external force.
Newton's Second Law of Motion states that the acceleration of a physical object is directly proportional to the net force acting on the physical object and inversely proportional to its mass.
Mathematically, it is given by the formula;
[tex] Acceleration = \frac {Net \; force}{mass} [/tex]
Let's assume the following values;
Mass of object B = 10 kg
Mass of object A = 2 * B = 2 * 10 = 20 kg
Acceleration = 5 m/s²
I. To find the force for B;
[tex] Force = mass * acceleration [/tex]
[tex] Force = 10 * 5 [/tex]
Force B = 50 Newton
II. To find the force for A;
[tex] Force = mass * acceleration [/tex]
[tex] Force = 20 * 5 [/tex]
Force A = 100 Newton
From the calculation, we can deduce that Force A (100 N) is twice or double the value of Force B (50 N).
In conclusion, since object A has twice the mass of object B and both objects are moving at the same speed, object A would require twice the force to stop as Object B.
"" 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.
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.
Claire rides her scooter to school, traveling 25 km/h. How much time in minutes does it take her to travel to her school, which is 4 km away ?
Answer:
9.6 minutes
Explanation:
We have that it takes Claire [tex]t=0.16h[/tex] amount of time to get to school
[tex]t=0.16h[/tex]
From the Question we are told that
Velocity[tex]v= 25 km/h.[/tex]
Distance [tex]d=4km[/tex]
Generally the equation for Time is mathematically given as
[tex]v=\frac{d}{t}\\\\t=\frac{4}{25}\\\\t=0.16h[/tex]
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calculate the voltage applied to 2.00
Answer:
Here is your answer
Explanation:
1.55 V is the answer
hope u like it
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
A train starts from rest and leaves Greenburg station with an acceleration of 1.20 meters per second2. How long does it take the train to travel a distance of 500 meters?
Answer:
Time, t = 28.87 seconds
Explanation:
Given the following data;
Acceleration = 1.20 m/s²
Distance = 500 meters
Initial velocity = 0 m/s
To find the time to cover the distance, we would use the second equation of motion;
[tex] S = ut + \frac {1}{2}at^{2}[/tex]
Where;
S represents the displacement or height measured in meters.
u represents the initial velocity measured in meters per seconds.
t represents the time measured in seconds.
a represents acceleration measured in meters per seconds square.
Substituting into the equation, we have;
[tex] 500 = 0*t + \frac {1}{2}*(1.2)*t^{2}[/tex]
[tex] 500 = 0 + 0.6*t^{2} [/tex]
[tex] 500 = 0.6t^{2} [/tex]
[tex] t^{2} = \frac {500}{0.6} [/tex]
[tex] t^{2} = 833.33 [/tex]
Taking the square root of both sides, we have;
[tex] t = \sqrt{833.33} [/tex]
Time, t = 28.87 seconds
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.
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
pleaase help me i don't know this !!!
Answer:
coefficient=1.09N/m×g
coefficient=1.09N/0.413g×10m/s square
coefficient=1.09N/4.13N
coefficent=0.263
f= uK
here f is force, u is cofficient of friction , k is normal force
k = mg
f = umg
1.09 = u × 0.41 × 10
u = 1.09 ÷ 4.1
u = 0.26
I need help answer these questions please
Answer:
1. 25 J
2. 250 J
3. 900,000 J
4. 7,500 J
Explanation:
1. The distance the wheelbarrow is tilted, d = 0.5 m
The force used to tilt the wheelbarrow, F = 50 N
The work done, W = F × d
∴ W = 50 N × 0.5 m = 25 J
2. Work done, W = Force × Distance
The applied force, F = 50 N
The distance the sand is moved, d = 5 m
∴ W = 50 N × 5 m = 250 J
3. The work done, W = The load lifted × The height to which the load is lifted
∴ W = 90,000 N × 10 m = 900,000 J
The work done, W = 900,000 J
4. The work output of the skateboard = The work input × Efficiency
Given that the skateboard is an ideal machine, we have;
The work output of the skateboard = The work input = W
W = F × d
F = 15 N, d = 500 m
∴ W = 15 N × 500 m = 7,500 J
The work output of the skateboard = W = 7,500 J.
