Explanation:
Red, green, and blue are therefore called additive primaries of light. ... When you block two lights, you see a shadow of the third color—for example, block the red and green lights and you get a blue shadow. If you block only one of the lights, you get a shadow whose color is a mixture of the other two.
First, your definition of a shadow is incorrect. A shadow is an area that receives less light than its surroundings because a specific source of light is blocked by whatever is "casting" the shadow. Your example of being outside reveals this. The sky and everything around you in the environment (unless you are surrounded by pitch black buildings) is sending more than enough light into your shadow, to reveal the pen to your eyes. The sky itself diffuses the sunlight everywhere, and the clouds reflect plenty of light when they are not directly in front of the Sun.
If you are indoors and have two light bulbs, you can throw two shadows at the same time, possibly of different darknesses, depending on the brightness of the light bulbs.
It can take a lot of work to get a room pitch black. One little hole or crack in some heavy window curtains can be enough to illuminate the room. There are very few perfectly dark shadows.
Para fabricar la bicicleta de un niño pequeño se tiene en cuenta que la fuerza que puede desarrollar es menor que la de un adulto y que no sabe cambiar de desarrollo. Por ello, se fabrica con un solo plato y un solo piñón de desarrollo muy pequeño. El plato es de 28 dientes y el radio de la rueda mide 20 cm. Si queremos que el desarrollo sea de 1,4 calcula: - El número de dientes que debe tener el piñón de la bicicleta. - Cuántos metros avanza la bicicleta por cada pedalada completa.
Answer:
a) El piñón debe tener 20 dientes.
b) La bicicleta avanza aproximadamente 1,759 metros por cada pedaleada completa.
Explanation:
a) El plato es el engranaje más grande que forma parte del sistema de transmisión, acompañando a la cadena y el piñón integrado a la rueda trasera. Asumiendo que no existen pérdidas por fricción seca y que las condiciones de lubricación del sistema de transmisión son óptimas tal que las pérdidas de potencia son despreciables. Además, supongamos que la bicicleta viaja a velocidad constante, entonces tenemos la siguiente identidad mediante las definiciones de trabajo y potencia:
[tex]T_{P}\cdot \omega_{P} = T_{p}\cdot \omega_{p}[/tex] (1)
Donde:
[tex]T_{P}[/tex] - Torque del plato, en newton-metros.
[tex]T_{p}[/tex] - Torque del piñón, en newton-metros.
[tex]\omega_{p}[/tex] - Rapidez angular del piñón, en radianes por segundo.
[tex]\omega_{P}[/tex] - Rapidez angular del plato, en radianes por segundo.
Sabiendo el hecho que tanto el plato y el piñón experimenta la misma velocidad tangencial, podemos simplificar (1) como sigue:
[tex]\frac{T_{P}}{R_{P}} = \frac{T_{p}}{R_{p}}[/tex] (1b)
Puesto que el radio de cada elemento y el número de dientes son, por separado, directamente proporcionales al número de dientes, modificamos (1b) así y tenemos la siguiente identidad, la cual equivale a su vez a la razón de desarrollo:
[tex]\frac{T_{P}}{T_{p}} = \frac{N_{P}}{N_{p}} = \frac{R_{P}}{R_{p}} = \frac{\omega_{p}}{\omega_{P}}[/tex] (1c)
Donde:
[tex]N_{p}[/tex] - Número de dientes del piñón, sin unidad.
[tex]N_{P}[/tex] - Número de dientes del plato, sin unidad.
Si tenemos que [tex]r = 1,4[/tex] y [tex]N_{P} = 28[/tex], entonces tenemos que el número de dientes del piñón es:
[tex]r = \frac{N_{P}}{N_{p}}[/tex]
[tex]N_{p} = \frac{N_{P}}{r}[/tex]
[tex]N_{p} = \frac{28}{1,4}[/tex]
[tex]N_{p} = 20[/tex]
El piñón debe tener 20 dientes.
b) De acuerdo con la relación de desarrollo, por cada revolución realizada por el plato, el piñón realiza 1,4 revoluciones. Entonces, el avance realizado por la rueda trasera ([tex]s[/tex]), en metros, es igual al productor de la relación de desarrollo y la circunferencia de la rueda, es decir:
[tex]s = r\cdot 2\pi\cdot R[/tex] (1)
Donde [tex]R[/tex] es el radio de la rueda trasera, en metros.
Si conocemos que [tex]r = 1,4[/tex] y [tex]R = 0,2\,m[/tex], entonces el avance realizado por la rueda trasera es:
[tex]s = r\cdot 2\pi\cdot R[/tex]
[tex]s = (1,4)\cdot (2\pi)\cdot (0,2\,m)[/tex]
[tex]s \approx 1,759 \,m[/tex]
La bicicleta avanza aproximadamente 1,759 metros por cada pedaleada completa.
relative density of a solid is 2.5 if its volume is 7.5 m³and then find its mass
hope it is helpful to you
As global population ______
a.) increases b.) decreases
food production must _____
a.) increase b.) decrease
Answer:
As global population a.) increases food production must a.) increase.
Example:
More people means more food must be produced.
Which material is colder in a room where all the objects are in for a long time?
A. all objects are the same temperature
B. wooden desk
C. a metal chair
D. a smart board
Which of the following is an example of uniform circular motion?
A. Swinging on a swing
B. Spinning on a merry-go-round
C. Sliding down a slide
D. Bouncing on a trampoline
Answer:
B
Explanation:
First narrow answers to CIRCULAR motion.
Only A and B have circular motion.
Second look at the keyword UNIFORM. A swing does not have uniform motion because it will accelerate due to gravity and have the most velocity at the bottom of the swing.
Therefore, it must be B.
The image shows street lights powered by solar panels. Which sequence shows the energy transformations taking place in these lights?
A.
gravitational potential energy → vibrational energy → chemical potential energy
B.
radiant energy → chemical potential energy → motion energy
C.
radiant energy → electric energy → radiant energy
D.
sound energy → chemical potential energy → radiant energy
E.
gravitational potential energy → motion energy → radiant energy
Answer:
the answer is c
Explanation:
i did the test
What is the power of a hair dryer with a current of 4 A and a resistance of 60 ohms?
Answer:
960W
Explanation:
v=R×I
v=60ohm.4A=240v
p=VI
p=240v.4A
p=960W
The power of a hair dryer with a current of 4 A and a resistance of 60 ohms is 960 W.
What is power?
The amount of work completed in a given amount of time. Watt (W), which is derived from joules per second (J/s), is the SI unit of power. Horsepower (hp), which is roughly equivalent to 745.7 watts, is a unit of measurement sometimes used to describe the power of motor vehicles and other devices.
Given in the question a hair dryer with a current of 4 A and a resistance of 60 ohms power, p
Voltage, v=R×I
v=60 ohm.4 A=240 v
power, p=VI
p=240 v.4 A
p=960 W
The power of a hair dryer with a current of 4 A and a resistance of 60 ohms is 960 W.
To learn more about power refer to the link:
brainly.com/question/2289248
#SPJ2
Amos runs up a flight of stairs with a. total change in energy E. Vanessa exerts double the amount of energy in twice the time. How does Amos power output, Pa compare with Vanessa's power output, Pv?
Answer: Pa=Pv
Explanation:
Khan academy
Amos runs up a flight of stairs with a total change in energy ΔEA. Vanessa exerts double the amount of energy in twice the time.
How does Amos’s power output, PA, compare with Vanessa’s power output, Pv?
Answer: Pa=Pv
Uranium-235 decays to thorium-231 with a half-life of 700 million years. When a rock was formed, it contained 6400 million uranium-235 nuclei and no thorium-231 nuclei. Show that after 2100 million years there are seven times more thorium nuclei than uranium nuclei in the rock.
Answer:
proof in explanation
Explanation:
First, we will calculate the number of half-lives:
[tex]n = \frac{t}{t_{1/2}}[/tex]
where,
n = no. of half-lives = ?
t = total time passed = 2100 million years
[tex]t_{1/2}[/tex] = half-life = 700 million years
Therefore,
[tex]n = \frac{2100\ million\ years}{700\ million\ years}\\\\n = 3[/tex]
Now, we will calculate the number of uranium nuclei left ([tex]n_u[/tex]):
[tex]n_u = \frac{1}{2^{n} }(total\ nuclei)\\\\n_u = \frac{1}{2^{3} }(6400\ million)\\\\n_u = \frac{1}{8}(6400\ million)\\\\n_u = 800\ million[/tex]
and the rest of the uranium nuclei will become thorium nuclei ([tex]u_{th}[/tex])
[tex]n_{th} = total\ nuclei - n_u\\n_{th} = 6400\ million-800\ million\\n_{th} = 5600\ million[/tex]
dividing both:
[tex]\frac{n_{th}}{n_u}=\frac{5600\ million}{800\ million} \\\\n_{th} = 7n_u[/tex]
Hence, it is proven that after 2100 million years there are seven times more thorium nuclei than uranium nuclei in the rock.
LAST ONE NEED HELP.A car accelerates from rest to 20 m/s, in 5 seconds. The car exerts a force of 6000 N. What is the mass of the car?Single choice.
(2 Points)
1800 kg
1500 kg
1000 kg
900 kg
Answer:
1500kg
Explanation:
Initial velocity(u)=0m/s
Final velocity(v)=20m/s
Time taken=5s
Acceleration=v-u/t
Acceleration=20-0/5=4m/s^2
Force=6000N
Mass=?
Mass=Force/acceleration
= 6000/4
=1500kg
A ladybug crawls vertically on a leaf. Its motion is shown on the following graph of vertical position y vs. time t. What is the average speed of the ladybug between the times t=4s and t=7s?
0.67 m/s
0 m/s
-0.67 m/s
1.5 m/s
wait how does this work hehe this is kinda fun lol yay
An object is dropped without initial speed
from a height of 20 m above ground and falls
with a constant acceleration of 10 m.s-2.
a. How long does it take the object to
reach the ground?
b. What is its speed upon reaching
ground?
Answer:
a. t = 2 s
b. vf = 20 m/s
Explanation:
a.
We can the second equation of motion to find out the time to reach the ground:
[tex]h = v_it + \frac{1}{2}at^2[/tex]
where,
h = height = 20 m
vi = initial velocity = 0 m/s
t = time taken to reach the ground = ?
a = acceleration = 10 m/s²
Therefore,
[tex]20\ m = (0\ m/s)t+\frac{1}{2} (10\ m/s^2)t^2\\\\t^2 = \frac{20\ m}{5\ m/s^2}\\\\t = \sqrt{4\ s^2}[/tex]
t = 2 s
b.
Here, we will use the first equation of motion to find the final speed:
[tex]v_f = v_i + at\\v_f = 0\ m/s + (10\ m/s^2)(2\ s)[/tex]
vf = 20 m/s
Starting circuit One battery. 2 light bulbs in parallel; switch What is the voltage across the battery? What is the voltage across light bulb 1? What is the voltage across light bulb 2?
Answer:
The voltage across light bulb 1 and light bulb 2 is the the same i.e V
Explanation:
In a parallel circuit, the Voltage is same across all the components of the circuit and the current flowing through each component is added to get the total current across the circuit.
Let us say, the voltage across the circuit is V. The voltage across light bulb 1 and light bulb 2 is the the same i.e V
Which geologic events occur most often at this mid-oceanic ridge plate
boundary? *
2 points
Mid-oceanic ridge
plate boundary
Shelf
Sea level
Patella
Plate 2
Continental
crust
Rigid mantle
Asthenosphere
magnetic pole reversals and cooling of ocean water
hydrospheric pollution and adiabatic heating
earthquakes and volcanic eruptions
Answer: Earthquakes and Volcanic eruptions
Explanation:
You did not attach a picture however, this should be the correct answer.
Mid-oceanic ridge plate boundaries such as the Mid-Atlantic Ridge form as a result of plate separating at the boundary. This leads to earthquakes due to the forces of tension acting on the plates.
When this happens, the mantle is exposed and therefore there will be volcanic eruptions as the lava comes to the surface as magma. When this magma cools it creates new seafloors and underwater mountains.
A teacher performing a demonstration finds that a piece of cork displaces 23.5 cm3 of water. The piece of cork has a mass of 5.7 g. What is the density of the cork
Answer:
Density = 0.243 g/cm³
Explanation:
Volume of cork = 23.5 cm³
Mass = 5.7 g
To find the density of the cork;
Density can be defined as mass all over the volume of an object.
Simply stated, density is mass per unit volume of an object.
Mathematically, density is given by the formula;
[tex]Density = \frac{mass}{volume}[/tex]
Substituting into the formula, we have;
Density = 5.7/23.5
Density = 0.243 g/cm³
An nfl wide reciver can reach a top speed of 10 m/s in only 2.4 seconds. What is the nfl players acceleration
Answer:
The acceleration of the nfl players is 4.167 m/s²
Explanation:
Given;
velocity of the nfl players, v = 10 m/s
time of motion of the nfl players = 2.4 s
Acceleration is the change in velocity with time.
The acceleration of the nfl players is calculated as follows;
a = v/t
where;
a is the acceleration of the nfl players
a = 10 / 2.4
a = 4.167 m/s²
Therefore, the acceleration of the nfl players is 4.167 m/s²
3. Which of the following statements about a scientific theory is wrong?
What are the following statements?
what does the slope of a velocity-time graph reveal about an objects motion
Answer:
The slope of a velocity graph represents the acceleration of the object. So, the value of the slope at a particular time represents the acceleration of the object at that instant.
Answer:
The slope of a velocity graph represents the acceleration of the object.
Explanation:
So, the value of the slope at a particular time represents the acceleration of the object at that instant.
An electric circuit consists of light bulb with resistance of 10.0 ohm is connected to a
voltage source. The source provides a current of 2.00 mA in the bulb. What is the power
of the light bulb?
Answer:
P=I²R
Explanation:
P=2*10^-3 square times 10
4 times ten raise to power minus 5
NEED HELP A 400 Ω resistor is connected across 200 V. What current will flow?Single choice.
(2 Points)
0.25 A
0.5 A
2.0 A
4.0 A
Answer: 0.5A
Explanation:
According to Ohm's law, the Voltage(V) when a current flows through a resistor can be calculated by using the formula:
V = IR
where,
V = Voltage = 200V
I = current in amps (A)
R = resistance in ohms (Ω) = 400Ω
Current = Voltage / Resistance
I = V/R
I = 200/400
I = 0.5A
Therefore, the current is 0.5 Ampere
When a +0.00235 C charge
moves from point A to point B, its
electric potential energy increases
by 0.418 J. What is the potential
difference between A and B?
Include the correct sign, + or - .
(Unit = V)
Answer:177.87
Explanation:
Sound waves are blank waves
A) Longitudinal
B) mechanical
C) compression
D) all if the above
If the impulse applied to an object is 34 Ns when a force Facts on it
for 3 s, then the force acting on it is which of the following?
Answer:
Force = 11.33 Newton
Explanation:
Given the following data;
Impulse = 34 Ns
Time = 3 seconds
To find the force acting on the object;
Impulse = force * time
Substituting into the formula, we have;
34 = force * 3
Force = 34/3
Force = 11.33 Newton
Note: the impulse of an object is equal to the change in momentum experienced by the object.
Which is NOT a way to stay safe from static electricity?
a lightning rod on a building
a metal spike in an airport runway
a run through an open field during a lightning storm
an anti-static chain on a large truck
Answer: C is correct :)
Explanation:
After going through the hoop, a basketball falls to the floor 3 meters below the hoop. The ball
has a kinetic energy of 17.6 Joules as it strikes the ground. What is the potential energy at the hoop?
Answer:
immma send you the link friend me on hereExplanation:
Which of the following is TRUE about thermal equilibrium?
Answer:
option one
Explanation:
equilibrium is used to describe the point in which something meets in this case the temperature of an object
which instrument determine the purity of milk
Answer:
Milk Lactometer
Milk Lactometer: A lactometer is an instrument that is used to check for the purity of milk by measuring its density.
lactometer is used to determine the purity of milk
hope it is helpful to you
Why does it take more force to move a heavy box up a ramp than to move the same box down the ramp?
A.There is more friction on the bottom of the box when going up a ramp.
B.Gravity is pushing the box up the ramp at the same time you are pushing the box up the ramp.
C.When you push an object up a ramp, you are working against atmospheric pressure, which is pushing down.
D.When you push an object up a ramp, you are working against gravity, which pulls the box downward.
Science Check: Light Waves and Their Behavior 4 of 104 of 10 Items Question POSSIBLE POINTS: 1 Why is a light wave not considered a matter wave? A light wave is visible to humans. A light wave is visible to humans. A light wave moves faster than most waves. A light wave moves faster than most waves. A light wave does not have a wave length. A light wave does not have a wave length. A light wave travels through the vacuum of space. A light wave travels through the vacuum of space.
Answer:
A light wave travels through the vacuum of space
Explanation:
A light wave cannot be a matter wave because a matter wave is made up of
atoms while light wave is a form of radiation (electromagnetic). A matter wave requires a medium to travel while a light wave do not require medium to travel. Since light wave is a form of radiation, light can travel in vacuum.
Hence, the correct answer is A light wave travels through the vacuum of space