Answer:
a) t = 20 s, b) x = 1000 m, As the runway is only 800 m long, the plane cannot land at this distance
Explanation:
This is a kinematics exercise
a) in minimum time to stop,
v = vo + at
v = 0
t = -v0 / a
we calculate
t = -100 / (5.00)
t = 20 s
b) Let's find the length you need to stop
v² = vo² + 2 a x
x = -v0 ^ 2 / 2a
x = - 100² / 2 (-5.00)
x = 1000 m
As the runway is only 800 m long, the plane cannot land at this distance.
Indoor pollution experts conducted an analysis of the paint used in many office buildings which revealed that the paint contains traces of lead. The lead seems to rise to the surface of the paint and escape into the building's air supply. Tests show that because of the chemical drying process, the lead is not discernible on the surface until the paint has been on the walls for at least six months. To meet safety standards, owners should repaint walls at least every six months, or cover the walls with a different material.Which of the following, if true, would most weaken the conclusion above?A) The indoor pollution experts had no clear understanding of why it took six months for the lead to become discernible on the paint's surface.B) The indoor pollution experts neglected to examine the paint for traces of other toxic substances such as cadmium and mercury.C) The amount of lead found on the surface of the paint after six months remained constant for the next two years.D) The indoor pollution experts found that even in those offices painted with a different brand of paint, traces of lead were still found in the air workers breathed.E) The indoor pollution experts' research shows that the amounts of lead that come into contact with the air people breathe, even in the office buildings that used the greatest amount of paint, are too low to affect workers.
Answer:
E) The indoor pollution experts' research shows that the amounts of lead that come into contact with the air people breathe, even in the office buildings that used the greatest amount of paint, are too low to affect workers
Explanation:
The conclusion that would weaken the above statement if true was that the amount of lead found in air was not hazardous for the people living in building and the effects of such paint was quite low o affect workers.How can you say gravitational force is a field force
Answer:
because gravity pulled us in the land if there is no gravitational force there will not be field force too
Explanation:
hope it's will help you
a sphere of diameter 6.0
cm is moulded into a thin wire of diameter 0.2 mm calculate the length of the wire in metres
Answer:
V1 = 4/3 pi R^3 = pi D^3 / 6 D = 2 R volume of sphere
V2 = pi r^2 L = pi d^2 L / 4 volume of wire
V2 / V1 = 1 = 3/2 d^2 L / D^3 since volumes are equal
L = 2/3 D^3 / d^2 = 2/3 * 6^3 / .02^2 = 360,00 cm = 3600 m
you now barbecue is hot, but have you ever thought about the methods of heat transfer related to barbecue?
a) at your barbecue party, what would be an example of heat by conduction?
b) at your barbecue party where would heat be transferred b convection?
c) there is also radiation from the barbecue. where would you best feel this?
d) in some grill oven you put your meat under the heating element your meat is grilled by the heat coming from above. it will take longer to cook this meat than a similar piece on the barbecue can you explain this?
Answer:
Explanation:
There are three modes of heat transfer.
1. Conduction: It is the mode of heat transfer when the object is in contact with hot body and gradually the heat transfer from the hot end to the cold end.
2. Convection: It is the mode of heat transfer in which the molecules gets heated and moves up and the cold molecules comes down and the process continues till the entire liquid or gas is at same temperature.
3. Radiation: It is the process of heat transfer in which the heat is transferred in the form of heat waves.
(a) When the cook pot is placed on flame, it is the example of conduction.
(b) When the liquid is placed on the flame in a container, the liquid gets heated by the mode of convection.
(c) We feel heat as we stand near the flame so it is the example of radiation.
(d) because the heat is trapped so it becomes hot in lesser time.
Cho hai điện trở R1 = 12Ω và R2 = 18Ω được mắc nối tiếp nhau. Điện trở tương R12 của đoạn mạch có thể nhận giá trị nào trong các giá trị
Answer:
For two resistors R1 = 12Ω and R2 = 18Ω are connected in series. The equivalent resistance R12 of the circuit can take any of the values
(1) A string of constant thickness and length I cm is stretched by a force of T Newton. A
tuning fork stamped 256 Hz sets the string vibrating at its fundamental frequency.
Find the frequency of the string when:
(i) Its length is doubled and the tension constant;
(ii) the tension is doubled and the length constant.
2) State the effect of increase in the tension on a wire on its frequency.
Answer:
Explanation:
i) frequency is the square root of the quotient of Tension over linear density/ all divided by two times the length.
linear density and tension are constant, so the numerator remains constant
The length is doubled, so the frequency is halved.
f = 128 Hz
ii) Doubling the tension increases the frequency by √2
f = 256√2 = 362 Hz
2) If other factors remain constant, increasing tension increases frequency.
How does a fuse work?
A. A material burns out when current is excessive
B. A material burns out when resistance is excessive
C. A material burns out when voltage is excessive
D. A material acts as a switch to prevent electricity from flowing when voltage is excessive
Answer:
A. a material burns out when current is excessive
Why does a small piece of steel rod sinks while a large steel oil tanker floats?
Plss help thanks! pls include EXPLANATION and EXAMPLES that I can proof to people that has no knowledge
Answer:
Too what i know its because of the air
Explanation:
The steel rod is more dense and doesnt have air whil'st the oil tanker is less dense with lots of air
Please round 1045.2 to three significant digits
Answer:
1040
Explanation:
The rules for significant digits is that non-zero digits are significant figures. The zero in between 1 and 4 is significant because any zeroes between two significant digits are significant. Trailing zeroes if there is no decimal point are insignificant.
The number 1045.2 rounded to three significant digits would be 1040 because the rightmost zero is not a significant digit.
What are significant figures?In positional notation, significant figures refer to the digits in a number that is trustworthy and required to denote the amount of something, also known as the significant digits, precision, or resolution.
The definition of a significant digit according to the criteria is a non-zero digit. Any zeroes between two significant digits, such as the one between 1 and 4, are noteworthy. In the absence of a decimal point, trailing zeroes are not relevant.
According to the criteria for significant digits, non-zero digits are important numbers. The zero between 1 and 4 is crucial, as is any zero between two significant digits. The trailing zeroes are irrelevant if there is no decimal point.
Thus, the number 1045.2 rounded to three significant digits would be 1040.
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Hess's law states that:
A. Energy cannot be created nor destroyed, it can only change form.
B. The enthalpy change when 1 mole of a substance undergoes complete combustion under standard conditions is equal to molar masses of the compounds.
C. When the enthalpy changes under standard conditions, 1 mole of a substance is formed from its elements.
D. The overall enthalpy change for a reaction is independent of the route the reaction takes.
Answer:
D. The overall enthalpy change for a reaction is independent of the route the reaction takes.
Answer: Hess's law states that the overall enthalpy change for a reaction is independent of the route the reaction takes. Option D is correct.
It is given Hess's law.
It is required to state the Hess's law.
What is Hess's law ?Thermochemical equations can be manipulated to give the data chemical reactions. We find exactly how much energy will be absorbed or released by the reaction because we may face various explosions.
There are mainly two ways to calculate ΔH of any reaction. First If the reaction has ΔH then the reverse of the reaction will have opposite ΔH and the second is if double the ΔH of the substances, double the ΔH.
Therefore Hess's law states that the overall enthalpy change for a reaction is independent of the route the reaction takes.
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A 111 kg linebacker running at 1.9 m/s and a 82 kg quarterback running at 3 m/s have a head-on collision in midair. The linebacker grabs and holds onto the quarterback. (a) What is their combined speed immediately after the collision
Answer:
Explanation:
mass of linebacker, m = 111 kg
initial velocity, u = 1.9 m/s
mass of quarterback, m' = 82 kg
initial velocity, u' = 3 m/s
(a) Let they are moving in the same direction, the velocity is v after collision.
Use conservation of momentum
m u + m' u' = (m + m') v
111 x 1.9 + 82 x 3 = (111 + 82) v
v = 2.4 m/s
Let they are moving in opposite direction, the velocity is v after collision.
Use conservation of momentum
m u - m' u' = (m + m') v
111 x 1.9 - 82 x 3 = (111 + 82) v
v = - 0.18 m/s
A 4000 N force acts on an object that initially has a momentum of 400 kg-m/s for 0.9 seconds. What is the final momentum of the system?
Answer:
4360 Kgm/s
Explanation:
Applying,
Ft = M-M'................. Equation 1
Where F = force, t = time, M = Final momentum, M' = Initial momentum.
make M the subject of the equation
M = Ft+M'............ Equation 2
From the question,
Given: F = 4000 N, t = 0.9 seconds, M' = 400 kg-m/s
Substitute these values into equation 2
M = 4000+(0.9×400)
M = 4000+360
M = 4360 kgm/s
Hence the final momentum is 4360 kgm/s
What is conserved in a thermodynamically closed system?
A. Both energy nor matter
B. Energy
C. Both energy and matter
D. Matter
Explanation:
C. Both energy and matter
What is Anatomy & Physiology in 5 words?
Answer:
Anatomy is the study of the structure and relationship between body parts.
Physiology is the study of the function of body parts and the body as a whole.
Explanation:
can ya pls answer dis!
Answer:
Here Is An OverView of What I Know About Science:
To understand what science is, just look around you. What do you see? Perhaps, your hand on the mouse, a computer screen, papers, ballpoint pens, the family cat, the sun shining through the window …. Science is, in one sense, our knowledge of all that — all the stuff that is in the universe: from the tiniest subatomic particles in a single atom of the metal in your computer's circuits, to the nuclear reactions that formed the immense ball of gas that is our sun, to the complex chemical interactions and electrical fluctuations within your own body that allow you to read and understand these words. But just as importantly, science is also a reliable process by which we learn about all that stuff in the universe. However, science is different from many other ways of learning because of the way it is done. Science relies on testing ideas with evidence gathered from the natural world. This website will help you learn more about science as a process of learning about the natural world and access the parts of science that affect your life.
Explanation:
Science helps satisfy the natural curiosity with which we are all born: why is the sky blue, how did the leopard get its spots, what is a solar eclipse? With science, we can answer such questions without resorting to magical explanations. And science can lead to technological advances, as well as helping us learn about enormously important and useful topics, such as our health, the environment, and natural hazards. Without science, the modern world would not be modern at all, and we still have much to learn. Millions of scientists all over the world are working to solve different parts of the puzzle of how the universe works, peering into its nooks and crannies, deploying their microscopes, telescopes, and other tools to unravel its secrets. I Hope This Helps.
what will be the effect on the acceleration due to gravity of the earth if it is compressed to a the size the moon?
Answer:
it gravitional pull on earth will increased becauste it is compress to a form of moon which is comperatively smaller so the gravitonal pull on per cm of earth will incrased so we can say that there will be change in acceleration due to gravity
please ans both urgent
Answer:
d I guess not sure
b if down I guess
Explanation:
if worng then plz dont say anything as I am not sure about the ans
A city bus travels along its route from Jackson Street 8 km to Aurora Avenue, where it turns and continues 13 km.
What is the total distance that the bus has traveled? km
The total displacement of the bus is approximately 15 km northeast northwest southeast southwest.
im a bit confused on what the question is:(
if its just asking for the total number of km traveled it would be 21 km
The Doppler effect a. can be applied only to sound waves. b. is the basic explanation for the blue shift of light in our Universe. c. occurs when the frequency of sound waves received is lower if the wave source is moving toward you than if it's moving away. d. occurs when the pitch of a sound gets lower if the source is receding.
Answer:
a. can be applied only to sound waves.
c. occurs when the frequency of sound waves received is lower if the wave source is moving toward you than if it's moving away
d. occurs when the pitch of a sound gets lower if the source is receding.
Explanation:
[tex].[/tex]
A group of students are designing a field study to investigate the length of time a traffic light remains yellow.
Answer:
3 to 7 seconds.
Explanation:
According to the traffic engineers the length or the duration of the signal to turn form yellow or amber to green is more than 5 seconds. A time interval is needed to easy out the traffic flow."Measurement is essential in our life. Justify the statement.
Explanation:
Measurement plays an important role in our daily lives because they are useful to do basic tasks, such as taking the temperature of a child with the help of a thermometer,making time estimations,measure out medicines and find out weights, areas and volumes of different substances
Derived quantities depend on...........physical quantity
Derived quantities depend on.( fundamental)..........physical quantity
Are you from Nepal?
Answer:
Derived quantities depend on two or more physical quantity.
whats the beginning of life called
Answer:
Abiogenesis in evolutionary science, not sure about creation science
Explanation:
1.What is laser?
2.List the uses of laser in everyday life
Laser means Light Amplication by Stimulated Emission of Radiation.
Uses of laser
DNA sequencing instrument
Cutting and welding materials
Semiconducting chip manufacturing
Military devices
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A skier is standing still on a flat area of snow.
The weight of the skier is 550 N. The total area of his skis in contact with the ground is 0.015
m2.
What is the pressure exerted on the ground by the skier?
3700 N / m2
37 000 N/m2
8.3 N/m2
0.83 N/m2
We know
[tex]\boxed{\sf Pressure=\dfrac{Force}{Area}}[/tex]
[tex]\\ \sf\longmapsto Pressure=\dfrac{550}{0.015}[/tex]
[tex]\\ \sf\longmapsto Pressure=36666Pa[/tex]
[tex]\\ \sf\longmapsto Pressure=36666N/m^2[/tex]
Most nearest value is 37000N/m^2
Hence option b is correct
A ball that has a mechanical energy of 65 J has 12 J of kinetic energy. The ball has
J of potential energy
Answer:
The ball has a potential energy of 53 J.
Explanation:
Mechanical energy, E = Kinetic energy + Potential energy
E = K.E + P.E
65 = 12 + P.E
P.E = 65 – 12
P.E = 53 J
Therefore the potential energy of the ball is 53 J
Answer:
53
Explanation:
on e2021
the slope of a line on a position vs time graph is the
a. velocity
b. time
c. distance
d. displacement
It's the velocity, but only the magnitude. It can't show the direction of the velocity. So it's better to call it speed.
Is velocity ratio of a machine affected by applying oil on it?Explain with reason.
Answer:
It depends upon SAE No. of oil. (SAE means Society of Automotive Engineers). However, it usually does protect against friction.
Explanation:
If we use very viscous oil, it does not reach all the parts. Very thin oil will flows away easily and gets wasted. Grease is used in such cases. It is generally used around ball-bearing. Normal grease or oil is never used where there is high pressure, high temperature and high speed. Special lubricants are used in such cases. In cold season the oil becomes thick and in hot season it becomes thin. Therefore selection of lubrication also depends on the season. It is always advisable to refer operating manual of the equipment before selecting the lubricant.
The intensity of friction depends on following factors:
i) The area involved in friction.
ii) The pressure applied on the surfaces.
Force = Pressure ´ Area Frictional force will increase, if the area of contact will increase or if pressure applied on the surface increased.
Which of these factors make hydrogen fuel cells a better option than burning fossil fuels?
-Hydrogen fuel cells have a higher energy efficiency.
-Hydrogen fuel cells create less pollution.
-Burning fossil fuels relies on outdated devices and technology.
-Hydrogen is the most abundant element in the universe.
-Hydrogen fuel cells are more expensive than fossil fuels.
Answer:
it the second answer
Explanation:
because burning fossils pollute the environment
a teacher drives from school to the mall. then she goes to the doctors office for a physical examination. what is the magnitude of her displacement
The magnitude of the teachers displacement is the difference between
the location of the school and the location of the doctors office
The reason behind the above expression are explained as follows
The known locations of the teacher;
Initial location; The school
Second location; The mall
The eventual location; The doctors office
The required information;
The magnitude of the teachers displacement
The method of obtaining the displacement of the teacher;
Qualitatively, the displacement of the teacher can be obtained by applying the definition of displacement as follows;
The definition of displacement is an object's change in position, given by the difference between its start and finish locations
According to the definition of displacement, therefore, the magnitude of
the teachers displacement is the distance between the school and the
doctors office which is given by the difference between the coordinates of
the location of the school and the location of the doctors office
The magnitude of the displacement of the teacher = The coordinate of the location of the doctors office - The coordinate of the location of the school
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