Answer:
answer A is the correct one
Explanation:
Weber's law states that "the smallest discernible change of a stimulus and proportional to the stimulus".
Applying this law to cases of optical intensity, the ratio must be
k = cte = ΔI / I
where ΔI is the variation of the intensity and I is the value of the intensity
In general, for humans, the constant is 0.15 for the rods and 0.015 for the cones of the retina.
When reviewing the answers, answer A is the correct one, since in order for the previous relationship to be maintained, the magnitudes must rise proportionally
Which change(s) of state require an increase in energy?
Answer: Melting, evaporation and sublimation.
Melting, evaporation and sublimation require an increase in energy.
To determine the changes of state that require an increase in energy, we need to know about changes of state.
What are the changes of state of a substance?Melting, evaporation and sublimation are the changes of state of a substance.
How do melting, evaporation and sublimation require an increase in energy?In melting process, substance goes from solid to liquid state. In evaporation state, it goes from liquid to vapour state and in sublimation, it goes from solid to vapour state.In each of the above case, the bonds between molecules of the substance become weak due to getting of heat energy. And the heat energy is appeared as kinetic energy of the molecules.So the molecules vibrate rapidly which leads to the change of state.Thus, we can conclude that melting, evaporation and sublimation require an increase in energy.
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Which of the the following distance vs time graphs represents an object the is moving at constant non zero velocity
A pendulum can be formed by tying a small object, like a tennis ball, to a string, and then connecting the other end of the string to the ceiling. Suppose the pendulum is pulled to one side and released at t1. At t^2, the pendulum has swung halfway back to a vertical position. At t^3, the pendulum has swung all the way back to a vertical position. Rank the three instants in time by the magnitude of the centripetal acceleration, from greatest to least. Most of the homework activities will be Context-rich Problems.
Answer:
1- t^3
2- t^2
3- t1
Explanation:
The acceleration produced in a body, while travelling in a circular motion, due to change in direction of motion is called centripetal acceleration. The formula of the centripetal acceleration is as follows:
ac = v²/r
where,
ac = centripetal acceleration
v = speed
r = radius
for a constant radius the centripetal acceleration will be directly proportional to the speed of object. The speed of pendulum will be lowest at t1 due to zero speed initially. Then the speed will increase gradually having greater speed at t^2 and the highest speed and centripetal acceleration at t^3. Therefore, the three instants in tie can be written in following order from greatest centripetal acceleration to lowest:
1- t^3
2- t^2
3- t1
I need help with number 7 please.
The SPEED of a car on the highway is 75 mph.
(You're correct on #6.)
A hiker starts at point P and walks 2.0 km due east and then walks at an angle of 30 degrees north of east for 1.4 km.
Use the Pythagorean theorem to determine the resultant of the 2 vectors. This is the magnitude of the hiker’s displacement.
Answer:
The magnitude of the hiker’s displacement is 2.96 km
Explanation:
Let the initial displacement of the hiker, = x = 2km
the final displacement of the hiker, = y = 1.4 km
The resultant of the two vectors, According to Pythagorean theorem is the vector sum of the two vectors.
R' = x' + y'
Check the image uploaded for solution;
Write the equation for newtons third law
Answer:
Explanation:
Newtons third law says an applied force will produce an equal but opposite force.
[tex]F_A_B =-F_B_A[/tex]
An equiconvex lens has power 4D. what will be the radius OF curvature of each
Surface ľf the lens is made of glass of RI 1.5.
Which statement is true about the SI System?
A-Uses different base units than the English measurement system.
B-Is used in scientific
measurement.
C-Includes the meter as its base unit for length.
D-All of the above.
Answer:
maybe the answer is in is D part
3.An object that begins at rest has an acceleration of 2 m/s/s What is its instantaneous speed after 3 seconds?
What is the name of the force that acts between any two objects because of
their masses?
Answer:
Explanation:
The force of attraction between 2 masses.
What do the EM results indicate about what might is causing this disease?
Answer:
In the event of a disease caused by an unknown pathogen, it is hard to know which reagent to pick. ... EM, though it may not be able to identify a virus beyond the family level, at least ... Negative staining of stool specimens from these cattle demonstrated a ... This results in a fuzzy halo around the particles in negative stains.Explanation:
You throw a ball upwards at 22 m/s. How high will it go?
Answer:
24.69 meters
Explanation:
sorry if it's not right.
answer:
[tex]h=24.69m[/tex]
step-by-step explanation:
[tex]eg=mgh \\ek=\frac{1}{2} mv^2[/tex]
eg= gravitational energy
ek= kinetic energy
now, since no mass is given of the ball, both equations on their own do nothing for us, except leave us scratching our heads wondering how to figure out the problem. but, since the question states, “and no air resistance,” we now know, according to the law of conservation of energy, that the energy of the two equations will equal each other because none of the energy has dissipated or left the system.
the amount of energy present during the initial phase of the woman about to throw the ball will be present in the final phase, which will be at its highest point (according to this problem).
so now [tex]eg=ek[/tex]
knowing this, we can now set the equations equal
[tex]eg=ek\\mgh=\frac{1}{2} mv^2[/tex]
the two m’s cancel out, making the mass of the ball insignificant and not influential; next, substitute the values we are given in the problem
[tex](22m/s),(9.8m/s^2)\\m(9.8m/s^2)h=\frac{1}{2} m(22m/s)^2\\(9.8 m/s^2)h=\frac{1}{2} (22m/s)^2\\(9.8m/s^2)h=1/2 (484m^2/s^2)\\(9.8m/s^2)h=1/2 (242m^2/s^2)\\\\h= (242m^2/s^2)/(9.8m/s^2)[/tex]
as you can see, all units that need to be canceled out are indeed canceled, leaving us with just m, meters, which is what height is measured in
therefore, [tex]h=24.69m[/tex]
I will give you branilest
Describe a senario that demonstartes Newtons 3rd law. Include the terms action and reaction.
Answer:
Explanation:
if you bounce a tennis ball, it will come back up as an equal reaction to your action (dropping it). there is an equal but opposite reaction in this scenario, demonstrating newton's third law.
Answer:
when u jump in the air and hit the ground the ground applies the same force back which applies a opposite force which causes u to propel into the air
Explanation:
hope this helped :)
PLEASEEEEE THIS A TIMED TESTTTTTTTTT
Answer:
C
Explanation:
Answer:
that car got obliterated almost like the day my uncle said come with me
Explanation:
the outcome was not good
D.
(S. 15
10. The average velocity of a car is 54km/h. What is
the distance covered if the time taken is 10s
A. 200m B. 150m C. 100m D. 50m E.
Answer:
Option B 150 Metre
Hope this helps youAnswer:
B. 150 m
Explanation:
In order to answer the question, it is important to know the formula for "velocity."
velocity = [tex]\frac{distance}{time}[/tex]
What is being asked? The distance covered if the time taken is 10 sec.
So this means: velocity x time = distance
Step 1: Convert 10 sec. to hour.
10 sec. x [tex]\frac{1 hour}{3,600 sec.}[/tex] = 0.00278 hr.
Step 2: Plug in the values to the formula.
distance = 54 [tex]\frac{km}{hr}[/tex] x 0.00278 hr.
distance = 0.150 km
Step 3: The choices are in meters (m), so let's convert 0.150 km to meter.
0.150 km x [tex]\frac{1,000 m}{1 km}[/tex] = 150 meters
The answer is: 150 m
planets A & B are near each other but there is a large difference in their temperatures using the data in the table explain how the atmosphere of these two planets can influence the average temperature
Answer: Planet A is closer to the Sun and has much greater atmospheric pressure. This suggests that planet A has a thicker atmosphere. Planet A's atmosphere is also mostly made of carbon dioxide, which is a greenhouse gas. This gas retains heat, raising the surface temperature of planet A.
Explanation:
Planet A is closer to the Sun and has much greater atmospheric pressure. This suggests that planet A has a thicker atmosphere. Planet A’s atmosphere is also mostly made of carbon dioxide (CO2), which is a greenhouse gas. This gas retains heat, raising the surface temperature of planet A.
Hope this one help.
What are some examples of magmatism?
At serve, a tennis player aims to hit the ball horizontally, as shown in the figure.
(a) What minimum speed is required for the ball to clear the 0.90-m-high net about 15.0 m
from the server if the ball is “launched” from a height of 2.50 m?
(b) Where will the ball land if it just clears the net (and will it be “good” in the sense that it
lands within 7.0 m of the net)?
(d) How long will it be in the air?
(a) The minimum speed required for the ball to clear the net is 26.3 m/s.
(b) The horizontal distance of the ball when it clears the net is 11.3 m
(c) The total time spent in the air by the ball is 1 s.
Time of motion
The time of motion of the tennis ball is calculated by using the following kinematic equation as shown below;
[tex]h = h_0 + v_0_yt - \frac{1}{2} gt^2\\\\0.9 = 2.5+ 0 - \frac{1}{2} (9.8) t^2\\\\0.9 = 2.5 - 4.9t^2\\\\4.9t^2 = 1.6\\\\t^2 = \frac{1.6}{4.9} \\\\t^2 = 0.327\\\\t = \sqrt{0.327} \\\\t = 0.57 \ s[/tex]
Minimum speedThe minimum speed of the ball is calculated as follows;
[tex]v_x = \frac{X}{t} \\\\v_x = \frac{15}{0.57} \\\\v_x = 26.3 \ m/s[/tex]
Time of motion from top of the high netThe time of motion from top of the high net is calculated as follows;
[tex]t = \sqrt{\frac{2h}{g} } \\\\t = \sqrt{\frac{2\times 0.9}{9.8} } \\\\t = 0.43 \ s[/tex]
Horizontal range = 0.43 x 26.3 = 11.3 m
Total time in air = 0.57 s + 0.43 s = 1.0 s
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Ex 11 ) A salmon jumps vertically out of the water at an initial velocity of 6 m/s. What is
the height it will jump?
Answer:
1.84m
Explanation:
Given parameters:
Initial velocity = 6m/s
Unknown:
height of jump = ?
Solution:
To solve this problem, we have to apply the right motion equation:
V² = U² - 2gH
V is the final velocity
U is the initial velocity
g is the acceleration due to gravity = 9.8m/s²
H is the height
Final velocity is 0
Solve;
0² = 6² - 2x9.8xH
-36 = -19.6H
H = 1.84m
A ball is thrown straight upward with an initial velocity of 16m/s. What is its velocity at its highest point?
Answer:
its going very fast
Explanation:
An intrepid treasure-salvage group has discovered a steel box, containing gold doubloons and other valuables, resting in 80 ft of seawater. They estimate the weight of the box and treasure (in air) at 7000 lbf. Their plan is to attach the box to a sturdy balloon, inflated with air to 3 atm pressure. The empty balloon weighs 250 lbf. The box is 2 ft wide, 5 ft long, and 18 in high. What is the proper diameter of the balloon to ensure an upward lift force on the box that is 20% more than required
Answer: the proper diameter is 6.137 ft
Explanation:
first we find the volume of box using the relation, which is;
V = 2 x 5 x 1.5 = 15 ft³
we find the buoyant force on the box by calculating the weight of water displaced.
FB = V x y
where y is the specific weight of sea water(62.4 lbf/ft³)
so we Substitute
FB = 15 x 62.4 = 936 lbf
now we find the upward force required by the balloon
FR = (W - FB) x 120%
= 1.2 (W - FB)
where W is the weight of the box treasure(7000 lb)
so we Substitute,
FB = 1.2( 7000 - 936 ) = 7276.8 lbf
Because the universal gas constant contains a Rankine in its units, we make use of Rankine for our temperature
so we find the density of air at 3 atm using ideal gas relation,
Pair = p/RT
Here, p is the pressure acting (3 atm), R is the universal gas constant (1716 ft²/S²-R), and T is the temperature (520°R),
Substitute so we substitute
Pair = (3 * 2116.22) / (1516 * 520)
= 0.007114 lbf.ft³
next we find the specific weight of air;
Yair = Pair * g
g is acceleration due to gravity(32.2 ft/s²)
Yair =
0.007114 * 32.2
= 0.23 Ibf /ft³
Now we find diameter of the balloon by balancing the net force required
FR = (y - yair) * V - Wb
= (y - yair) x (π/6)d³ - Wb
d is the diameter of the balloon.
so we Substitute, 7276.8 lbf for FR,
62.4 Ibf/ft³ for y, 0.23 for lbf/ft³ for Yair, 350 lb for Wb
so
7276.8 = (62.4 - 0.23)πd³ - 250
d³ = 231.23 ft³
d = 6.137 ft
Therefore, the proper diameter is 6.137 ft
state and explain the changes in stability of the beaker when the water freezes to ice
Answer:
if the question is referring to what happens when ice freezes you could say that the water molecules have lass energy so they don't move around as much
I don't understand why will only the 12 ohms lamps turn on when the switch is in position 2. shouldn't the current flow like this (like I highlighted in the picture)?
why did Iran experience almost 80 times more deaths in the 20th Century than California, despite having the same seismicity?
Answer: poor construction of houses
Explanation:
Majority of the people that died in Iran were as a result of poor building methods coupled with the fact that there was lack of proper regulation.
California experienced a similar earthquake but due to safer construction methods, about three people died.
Due to population boom in Iran and house shortage, this resulted in builders building cheap houses which were not strong enough.
Two asteroides crashed. The crash caused both asteroids to change speed.Scientist wants to use the change in speed and motion to figure out which asteroide has more mass.Based on the information in the diagram which statement is correct ? In your answer explain ,explain what the forces were like and why the asteroids changed in motion
Astroid one has less asked her to. Able to use enough force to not only change or keep it self go in the same direction.
(a) If the initial speed both asteroids before collision is the same, then the asteroid with greater mass will have more momentum before collision while the asteroid with lesser mass will have greater momentum after collision.
(b) The force of the impact depends of the velocity change and time of collision of the asteroids.
According to the principle of conservation of linear momentum, the sum of the momentum of each asteroid before collision must equal the sum of their momentum after collision.
[tex]m_1 u_1 + m_2 u_2 = m_1v_1 + m_2 v_2[/tex]
where;
m is the mass of the asteroidsu is the initial speed of the asteroidsv is the final speed of the asteroidsIf the initial speed both asteroids before collision is the same, then the asteroid with greater mass will have more momentum before collision while the asteroid with lesser mass will have greater momentum after collision to conserve the momentum.
The force of the impact depends of the velocity change and time of collision of the asteroids.
[tex]F = \frac{m\Delta v}{t}[/tex]
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Proposed Exercise: Work-Energy Theorem
In the situation illustrated in the figure below, a 365 pile hammer is used to bury a beam. The hammer is raised to a height of 3.0 (point 1) above the beam (point 2) and released from rest, sinking the beam of 7.4 (point 3). The rails exert on the hammer a constant friction force equal to 54 . Using the work-energy theorem, calculate (a) the speed of the hammer at the exact instant it reaches point 2 and (b) the mean force exerted by the hammer on the beam when moving it from position 2 to 3.
Tip: the force requested in item (b) is equal to the normal force that the beam exerts on
the hammer.
Answer:
152,000 N
Explanation:
(a) Initial potential energy = final kinetic energy
mgh = ½ mv²
v = √(2gh)
v = √(2 × 10 m/s² × 3.00 m)
v = 7.75 m/s
(b) Work done on pile hammer = change in energy
FΔy = 0 − (mgh + ½ mv²)
F (-0.074 m) = -((365 kg) (10 m/s²) (0.074 m) + ½ (365 kg) (7.75 m/s)²)
F (-0.074 m) = -11220.1 J
F ≈ 152,000 N
9. Juan is 32 years old. What is his maximum target heart rate?
A 186
B. 187
C. 188
D. 189
Answer:
C. 188
Explanation:
Getting the "maximum target heart rate" of a person is very easy. All you have to do is to subtract Juan's age (32) from 220.
So, 220-32 = 188
Therefore, Juan's maximum target heart rate is 188.
When exercising, it is very important not to exceed the maximum heart rate in order to prevent straining yourself. The maximum target heart rate is also being used in order to get your actual "target heart rate." This will depend on the type exercise intensity you want, whether it is moderate or vigorous.
A woman driving a car traveling at 40 m/s slams on the brakes and decelerates at 4 m/s2. How far does the car travel before it stops?
Answer:
The car goes, x = 200 [m]
Explanation:
In order to solve this problem we must use the following kinematic equation.
[tex]v_{f} ^{2} =v_{i} ^{2} - (2*a*x)[/tex]
where:
Vf = final velocity = 0
Vi = initial velocity = 40 [m/s]
a = desacceleration = 4 [m/s^2]
x = distance traveled [m]
Note: The negative sign of the above equation indicates that the vehicle is slowing down
Now replacing:
0 = (40)^2 - (2*4*x)
(0 - 40^2) = - 8*x
x = 200 [m]
The amount of energy necessary to remove an electron from an atom is a quantity called the ionization energy, Ei. This energy can be measured by a technique called photoelectron spectroscopy, in which light of wavelength λ is directed at an atom, causing an electron to be ejected. The kinetic energy of the ejected electron (Ek) is measured by determining its velocity, υ (Ek= mυ2/2), and Ei is then calculated using the conservation of energy principle. That is, the energy of the incident light equals Ei plus Ek. What is the ionization energy of selenium atoms in kJ/mol if light with λ = 48.2 nm produces electrons with a velocity of 2.371x106 m/s? The mass, m, of an electron is 9.109x10-31 kg. (Round to the ones place.)
Answer:
The value is [tex]E_i = 1.5596 *10^{-18} \ J[/tex]
Explanation:
From the question we are told that
The wavelength is [tex]\lambda = 48.2 nm = 48.2 *10^{- 9 }\ m[/tex]
The velocity is [tex]v = 2.371*10^6 \ m/s[/tex]
The mass of electron is [tex]m_e = 9.109*10^{-31} \ kg[/tex]
Generally the energy of the incident light is mathematically represented as
[tex]E = \frac{h * c}{\lambda}[/tex]
Here c is the speed of light with value [tex]c = 3.0 *10^{8} \ m/s[/tex]
h is the Planck constant with value [tex]h = 6.62607015 * 10^{-34 } J\cdot s[/tex]
So
[tex]E = \frac{6.62607015 * 10^{-34 }* 3.0 *10^{8}}{48.2 *10^{- 9 }}[/tex]
=> [tex]E = 4.12 *10^{-18} \ J [/tex]
Generally the kinetic energy is mathematically represented as
[tex]E_k = \frac{1}{2} * m_e * v^2[/tex]
=> [tex]E_k = \frac{1}{2} * 9.109*10^{-31} * (2.371*10^6 )^2[/tex]
=> [tex]E_k = 2.56 *0^{-18} \ J [/tex]
Generally the ionization energy is mathematically represented as
[tex]E_i = 4.12 *10^{-18} - 2.56 *0^{-18}[/tex]
=> [tex]E_i = 1.5596 *10^{-18} \ J[/tex]
Consider a line charge as your source. What is the order of your steps when applying coulomb's law. Below is a sequence of events. Place them in the order they should occur, number 1 being the first item. Select the step number from the drop down next to each item. Items to order: 1. Plug in coulomb's law. 2. Line integrate the expression. 3. Find the position vector of your field point. 4. Find the distance vector between differential source charge and field point. 5. Define your reference. 6. Find the dynamic position vector of these differential charges. 7. Carve the line in differential segments and assign each segment differential charge.
Answer:
the correct order of events is: 5 7 6 3 4 1 2
Explanation:
In this exercise, you order the events to solve the problem of the electric field created by a line of charge a line of charge
the order of events is
a) We define a reference 5
b) cut the line into segments each one is a charge differential 7
c) find the vector of the position of charges 6
d) find the point where field is calculated 3
e) find the distance between each charge point and point of interest 4
f) insert Coulomb's law 1
f) perform the integral of line 2
therefore the correct order of events is: 5 7 6 3 4 1 2