Answer:
D. Friction slow down or stop objects in motion.
Although 0 dB is often referred to as the lower threshold of human hearing, it is important to realize that the human ear is not equally sensitive to all frequencies of sound. In other words, a particular noise may sound louder or softer depending on the frequency of the sound wave being transmitted. Because of this variation, scientists have defined a unit of loudness, called a phon, to represent the intensity of sound waves with a frequency of 1000 Hz. A 60-phon sound is one that is perceived by the human ear to have the same loudness as a sound wave with an intensity of 60 dB and a frequency of 1000 Hz.
Required:
a. At approximately what frequency do most people perceive the least intense sounds? Answer numerically in hertz to two significant figures.
b. Normal conversation has a sound level of about 60 dB. How many times more intense must a 100-Hz sound be compared to a 1000-Hz sound to be perceived as equal to 60 phons of loudness?
Answer:
20 Hz
15.8 times
Explanation:
A
Although the range of frequency for any human's ear is usually said to be between 20 Hz and 20 kHz. And since the question asked for the least intense frequency, that has to be 20 Hz. Essentially the frequency most people perceive the least intense sound is 20 Hz.
B
A 100-Hz sound must be 10^1.2 times or 15.8 times more intense compared to a 1000-Hz sound to be perceived as equal to 60 phons of loudness
An iron block of 12 kg undergoes a process during which there is a heat gain from the block at 2 kJ/kg, an elevation increase of 32 m, and a decrease in velocity from 40 m/s to 7 m/s. During the process, which also involves work transfer, the internal energy of the block increases by 70 kJ. Suppose the total energy of the system remains constant. Determine the work transfer during the process in kJ and indicate whether the work is done on/by the system.
Answer:
Explanation:
Total heat gain by the block ΔQ = 2 x 12 kJ = 24 kJ .
Gain of potential energy = mgh = 12 x 9.8 x 32 = 3.763 kJ
Decrease in kinetic energy KE = 1/2 x 12 ( 40² - 7² )
= 9.306 kJ
increase in internal energy ΔE = 70 kJ
ΔQ = ΔE + PE - KE + W , W is work done by the gas
Putting the values
24 = 70 + 3.763 - 9.306 + W
W = - 40.457 kJ .
Since W is negative that means work is done on the system .
The ancient Egyptians used the stars to _____.
predict annual flooding
make their calendar
harvest their crops
choose their pharaoh
Answer:
predict annual flooding
Answer:
I'm pretty sure it is b make their calander
Galileo
o did not believe friction existed
o believed that friction stopped objects in motion
o believed that friction kept objects in motion
О
assumed that in a frictionless environment objects would never move
Answer:
object would move but it could be difficult to slow down or stop.
Which statement best compares coal and ores?
Both are burned for energy.
Both take millions of years to form.
Both require oxygen to form.
Both are used to make coins.
Answer:
Option 2 both take millions of years to form
Explanation:
Both coal and ores take millions of years to form.
What are ores?Ore is a naturally occurring rock or silt that has precious minerals in it that may be extracted, processed, and sold for a profit. These minerals are usually metals. Mining is the process of removing ore from the soil. The valuable metals or minerals are then removed by treating or refining the ore, frequently through smelting.
The concentration of the desired ingredient in an ore is referred to as its grade. To decide if a rock has a high enough grade to be worth mining and is therefore regarded as an ore, the value of the metals or minerals it contains must be evaluated against the expense of extraction.
Typically, oxides, sulphides, silicates, or native metals like copper or gold are the minerals of interest. To separate the valuable components from the waste rock, ore must be treated. Numerous geological processes collectively known as ore genesis are responsible for the formation of ore deposits.
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The force that is applied to other objects from the electric field *
A. ions
B. electric field
C. electric force
D. static charge
Three joules of work is needed to shift 10 C of charge from one place to another. The potential difference between the places is ______. *
0.3 V
0.5 V
5 V
3 V
Answer:
The potential difference between the places is 0.3 V.
∴ 1st option i.e. 0.3V is the correct option.
Explanation:
Given
Work done W = 3J
Amount of Charge q = 10C
To determine
We need to determine the potential difference V between the places.
The potential difference between the two points can be determined using the formula
Potential Difference (V) = Work Done (W) / Amount of Charge (q)
or
[tex]\:V\:=\:\frac{W}{q}[/tex]
substituting W = 3 and q = 10 in the formula
[tex]V=\frac{3}{10}[/tex]
[tex]V=0.3[/tex] V
Therefore, the potential difference between the places is 0.3 V.
∴ 1st option i.e. 0.3V is the correct option.
4. Kenny Kinematic notes that he is at mile marker 334 on the highway. He travels south to mile marker 181. What is his displacement?
Answer:
153miles
Explanation:
Distance on the highway = +334miles
Distance through south = -181miles (towards the negative direction)
Displacement will be the sum of the distances
Displacement = +334-181
Displacement = 153miles
Hence the displacement is 153miles
This is the build up of substance such as pesticides in an organism and occurs when an organism absorb a substance at a rate faster than that at which the substance is lost
Answer:
which the substance is lost by catabolism and excretion.
Explanation:
If used with godly wisdom, the earth has sufficient resources to sustain its human population.
A woman accidentally drops a flowerpot from a windowsill at a height d above the street towards a man of height h standing below. The woman calls out to the man in just enough time for the man to move out of the way. If the man needs a time interval of Δt to respond to the warning, at what height above the street will the flowerpot be when the woman calls out the warning? (Use the following as necessary: d, h, Δt, v for the speed of sound, and g for gravitational acceleration.)
Answer:
h^2 - ( 2t_o v_s + 2v_s^2 /g) h + v_s^2 \ t_o^2 =0
The correct result is that of a positive height
Explanation:
For this exercise we use the kinematic relations, let's start by finding the time it takes for the sound to reach the man
v_s = y / t
t = [tex]\frac{y}{ v_s}[/tex]
this height is y = h
t = \frac{h}{ v_s}
the man has a response time of t = t₀, therefore
time to move is
t' = t - t₀
the initial height of flower pot is
y = y₀ + v₀ t' - ½ g t'²
when it reaches the floor the height is zero y = 0 and as the pot is dropped its initial velocity is zero v₀ = 0
0 = y₀ +0 - ½ g (t -t₀)²
if the initial height is i = h,
h = ½ g ([tex]\frac{h}{v_s}[/tex] - t₀)²2
[tex]\frac{2}{g} h[/tex] = [tex]\frac{h^2}{v_s^2}[/tex] - [tex]\frac{2t_o }{v_s} h[/tex] + t₀²
[tex]\frac{h^2}{v_s^2} - ( \frac{2t_o}{v_s} + \frac{2}{g} ) h + t_o^2 = 0[/tex]h2 / vs2 - (2nd / vs + 2 / g) h + to2 - = 0
[tex]h^2 - ( 2t_o v_s + 2v_s^2 /g) h + v_s^2 \ t_o^2 =0[/tex]
To know the height, you must solve the second degree equation, it is much easier with numerical values.
The correct result is that of a positive height
The combination of an applied force and a friction force produces a constant torque of 36.0 N⋅m on a wheel rotating on a fixed axis. While the force acts for 6.00 s, the angular velocity of the wheel increases from 0 to 10.0 rad/s. The force is removed and the wheel comes to rest in 60.0 s
a. Find the moment of inertia of the wheel.
b. Find the magnitude of the torque due to friction.
c. Find the total number of rotations during the 66.0 s.
d. Find the Kinetic energy of the wheel at 6.00 s when the force is removed.
Answer:
D. Find the kinetic energy of the wheel at 6.00 z when the force is removed.
Which is an example of positive peer pressure?
O A parent telling her son to wear his seatbelt.
O A student asking others to join the leadership club.
O a teen encouraging a friend to drink alcohol.
O A teacher telling his students to have a safe weekend.
Answer:
B. A student asking others to join the leadership club.
Explanation:
A parent isn't a peer, therefore can't be peer pressure. Drinking is negative for your body, therefore not positive peer pressure. A teacher isn't a peer, therefore the only answer left is B.
Which image represents a transverse mechanical wave?
Answer:
A
Explanation:
It is kinda like a spring.
The image which represents a transverse mechanical wave is A.
What is a mechanical wave?The wave has motion if all points on a wave vibrate at right angles to the direction of the wave propagation.
A transverse wave is a mechanical wave which is much like sinusoidal wave which has particles vibrating about their equilibrium position perpendicular to the direction of the motion of the wave.
Hence, the image which represents a transverse mechanical wave is A.
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EASY WORK! Yes it’s easy for other people but not me for people asking.Also click on the photo.
Answer: Force and Direction
Explanation:
Your bike is too big if your can't touch the ground A.Knees B.Hands C.Feet
Answer: C: Feet
Explanation: Why...
Matter is made of small particles to small to be seen. Which of these best describe evidence of this statement? 1. Tara’s crayons melted when she left them under the sun. 2. Kerris glass of water overflowed when she added ice. 3. Sams basketball expands as he pumps air into it. 4. Stephanie dropped a vase and it broke into pieces.
Answer:
Explanation:
I think the answer is statement no 3.
Hope it helps.
Answer:
1 Tara's crayons melted when she left them under the sun
Which describes increasing the efficiency of an energy resource?
switching from coal to solar
making cars that get better gas mileage
using biomass instead of coal
turning off the lights when leaving a room
Answer:
making cars that get better gas mileage
Answer: Making cars that get better gas
Explanation: Gradpoint
HELPPPPP
What can you infer about the strength and direction of forces experienced by the pod and space station when they collided? What evidence from today’s activities supports your inference?
Answer:
In the collision, the strength of the force exerted on the pod is greater than the strength of the force exerted on the space station, but those forces are exerted in opposite directions.
Explanation:
something that orbiys other things in space
Answer: well we all orbit the sun all the planets do so the
SuN
Explanation: two words common sense
A proud new Jaguar owner drives her car at a speed of 35 m/s into a corner. The coefficients of friction between the road and the tires are 0.70 (static) and 0.40 (kinetic). What is the minimum radius of curvature for the corner in order for the car not to skid
Answer:
178.6 m
Explanation:
Since the car moves in a circular path, it experiences a centripetal force, F = mv²/r where m = mass of car, v = speed of car = 35 m/s and r = radius of curvature of path.
Now, for the car not to skid, this centripetal force must be equal to the frictional force, F' acting in the opposite direction.
So, F' = μN where μ = coefficient of static friction(since the car does not move in this direction) and N = normal force = mg where m = mass of car and g = acceleration due to gravity = 9.8m/s²
F' = μmg
Since F = F'
mv²/r = μmg
dividing both sides by m, we have
v²/r = μg
multiplying both sides by r, we have
v² = μgr
dividing both sides by μg, we have
r = v²/μg
Here we use μ = coefficient of static friction(since the car does not move in this direction) = 0.70. Substituting the other variables into the equation, we have
r = v²/μg
r = (35 m/s)²/(0.70 × 9.8m/s²)
r = 1225 m²/s²/6.86m/s²)
r = 178.6 m
So, the minimum radius of curvature of the corner is 178.6 m
Help plz with both I’ll mark brainliest
energy in a stretched spring
Answer:
Elastic potential energy is the potential energy stored by stretching or compressing an elastic object by an external force such as the stretching of a spring. It is equal to the work done to stretch the spring which depends on the spring constant k and the distance stretched.
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A cyclist cover 6km in 20minutes. His speed is
Answer:
The speed of a cyclist is 0.3 km/min.
Explanation:
Given
The distance d = 6km Time t = 20 minutesTo determine
We need to determine the speed of a cyclist.
In order to determine the speed of a cyclist, all we need to do is to divide the distance covered by a cyclist by the time taken to cover the distance.
We know the formula involving speed, time, and distance
[tex]s=\frac{d}{t}[/tex]
where
s = speedd = distance coveredt = time takensubstitute d = 6, and t = 20 in the formula
[tex]s=\frac{d}{t}[/tex]
[tex]s=\frac{6}{20}[/tex]
Cancel the common factor 2
[tex]s=\frac{3}{10}[/tex]
[tex]s=0.3[/tex] km/min
Thus, the speed of a cyclist is 0.3 km/min.
Which of the following diagrams would be a good, strong magnet?
what is the mystery Greene discussion and why does he say it is something we should all care about
Answer:
The mystery that Greene discusses is that dark energy is causing the expansion of the universe to accelerate. However, this cannot be explained by the laws of Physics.
Explanation:
I majored in Physics
Canon launch is a 4.0 kg bowling ball with 50 J of kinetic energy what is the bowling ball speed
Answer:
5 m/s
Explanation:
50=1/2*4v^2
4*1/2=2
25*2=50
so...
square rood of 25 is 5
answer 5 m/s
sorry if that didn't make since
1
What kind of adaptation is a long neck on a tortoise? *
(10 Points)
O
A. Structural
B. Behavioral
a
C. Functional
a
D. Physiological
Answer:
The answer is ......... structural adaptation
Explanation:
because structural adaptations is a physical thinng in their body so its A please give me brainliest
Plzz answer correctly
Answer:
B.
Explanation:
Use Newton's laws of motion to explain why it is important that baseballs and softballs each have a small acceptable range of masses.
Explanation:
new non law neutron means neutral then it's important that baseball and softball features small respectable range of masses soft it means that when a ball hits anything hard it comes back by the Newton Law if the baseball is big and the small boy small and then if the contract with each other they ignore triple so when a ball hits the wall if the comeback because of the Mutants and when a big ball if we throw it to the wall it doesn't come that it comes back but in a very low way because it contains less neutrons in it if it is helpful please share with me