Answer:
a. 960 W b. One 1 kW room heater
Explanation:
a. The rate of heat conduction P = kA(T₂ - T₁)/d where k = 2 × 0.040 W/m-K = 0.080 W/m-K since the thermal conductivity of glass wool is 0.040 W/m-K and that of the material is twice the thermal conductivity of glass wool, A = area of walls = 120 m², T₁ = outside surface temperature = 5.0 °C, T₂ = inside surface temperature = 18.0 °C and d = thickness of wall = 13.0 cm = 0.13 m
P = kA(T₂ - T₁)/d
= 0.080 W/m-K × 120 m²(18.0 °C - 5.0 °C)/0.13 m
= 9.6 Wm/K × 13 K/0.13 m
= 124.8 Wm/0.13 m
= 960 W
b. The number of 1 kW room heater required will be
n = rate of heat conduction/power of one room heater = 960 W/ 1 kW = 960 W/1000 W = 0.96 ≅ 1
So we need only one 1 kW room heater.
whats suface tension
Answer: "Surface tension is a film of a liquid caused by the attraction of the particles in the surface layer by the bulk of the liquid, which tends to minimize surface area."
Hope this helps!
Answer:
Explanation:
Surface tension is the property of a liquid surface. It is an effect where the surface of the liquid is strong.
example - small insects can walk on water as they do not have enough weight to penetrate it.
This image might help you
Hope it helps
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An object is moving along a circular track of radius 7 m with constant speed 11 m/s. Its average velocity after 8 second of the start is
Answer:
0 m/s
Explanation:
Average velocity is displacement over time.
v_avg = Δx / Δt
Displacement is the distance between the start and the finish.
The circumference of the track is:
C = 2πr
C = 2π (7 m)
C ≈ 44 m
The distance covered by the object is:
d = vt
d = (11 m/s) (8 s)
d = 88 m
So the object travels 2 circumferences, meaning it ends back where it started. Therefore, the displacement is 0 m, and the average velocity is 0 m/s.
It is 5.00 km from your home to the physics lab. As part of your physical fitness program, you could run that distance at 10.0 km/hr (which uses up energy at the rate of 700 W ), or you could walk it leisurely at 3.00 km/hr (which uses energy at 290 W ).A. Which choice would burn up more energy? 1. running.2. walking.B. How much energy (in joules) would it burn?C. Why is it that the more intense exercise actually burns up less energy than the less intense one?
Answer:
a. Walking burns up more energy.
b. 1740 kJ
c. This is because more intense exercise releases a lot of energy in a short period of time, whereas, less intense energy releases it energy gradually over a long period of time.
Explanation:
a. We know energy W = Pt where P = power and t = time.
Now for walking, t = d/v where d = distance = 5.00 km and v = speed = 3.00 km/hr and P = 290 W
So, t = d/v = 5.00 km/3.00 km/hr = 5/3 hr = 5/3 × 3600 s = 6000 s
W = Pt = 290 W × 6000 s = 1740000 = 1740 kJ
Now for running, t = d/v where d = distance = 5.00 km and v = speed = 10.00 km/hr
So, t = d/v = 5.00 km/10.00 km/hr = 0.5 hr = 0.5 × 3600 s = 1800 s and P = 700 W
W = Pt = 700 W × 1800 s = 1260000 = 1260 kJ
Since walking burns up 1740 kJ and running burns up 1260 kJ, walking burns up more energy.
b. It burns up 1740 kJ
c. This is because more intense exercise releases a lot of energy in a short period of time, whereas, less intense energy releases it energy gradually over a long period of time.
A driver of a car stopped at a gas station to fill up his gas tank. He looked at his watch, and the time read exactly 4 : 45 4:45 p.m. At this time, he started pumping gas into the tank. At exactly 4 : 50 4:50, the tank was full and he noticed that he had pumped 12.5 12.5 gallons. What is the average rate of flow of the gasoline into the gas tank
Answer:
Explanation:
Average rate = gallons / minutes
If 12.5gallons in 5mins
Xgallons in 1mins
12.5/5 = 2.5gallons per minute
Brandon buys a new seadoo he goes 12 km north from the beach he jumps wakes for 6 km to the east the chases a boat 10 km north what distance did he cover what was his displacement
Answer:
Distance covered 28 km
displacement is 22.8 km North-East
Explanation:
Distance shows how far apart objects or points are from each other. The distance he covered is the sum of all the distance travelled. Therefore:
Distance covered = 12 km + 6 km + 10 km = 28 km
Displacement is a vector quantity (has direction). It is the overall change in position.
The total distance traveled north = 12 km + 10 km = 22 km
The distance traveled east = 6 km
The displacement (d) is:
d² = 22² + 6² = 484 + 36
d² = 520
d = √520 = 22.8 km
Therefore the displacement is 22.8 km North-East
Distance covered 28 km
displacement is 22.8 km North-East
The calculation is as follows:
Distance covered
= 12 km + 6 km + 10 km
= 28 km
Now
The total distance traveled north = 12 km + 10 km = 22 km
And,
The distance traveled east = 6 km
So,
The displacement (d) is:
[tex]d^2 = 22^2 + 6^2\\\\ d^2 = 520\\\\d = \sqrt520[/tex]
= 22.8 km
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Marco is conducting an experiment. He knows the wave that he is working with has a wavelength of 32.4 cm. If he measures the frequency as 3 hertz, which statement about the wave is accurate?
This question is incomplete; here is the complete question:
Marco is conducting an experiment. He knows the wave that he is working with has a wavelength of 32.4 cm. If he measures the frequency as 3 hertz, which statement about the wave is accurate?
A. The wave has traveled 32.4 cm in 3 seconds.
B. The wave has traveled 32.4 cm in 9 seconds.
C. The wave has traveled 97.2 cm in 3 seconds.
D. The wave has traveled 97.2 cm in 1 second.
The answer to this question is D. The wave has traveled 97.2 cm in 1 second.
Explanation:
The frequency of a wave, which is in this case 3 hertz, represents the number of waves that go through a point during 1 second. According to this, if the frequency of the wave is 3 hertz this means in 1 second there were 3 waves. Moreover, if you multiply the wavelength (32.4cm) by the frequency (3) you will know the distance the wave traveled in 1 second: 32.4 x 3 = 97.2 cm. This makes option D the correct one as the distance in 1 second was 97.2 cm.
Answer:Is D!
Explanation:TEAT(Sorry) -_-*
identify properties of a human body system
Answer:
integumentary, skeletal, muscular, nervous, endocrine, cardiovascular, lymphatic, respiratory, digestive, urinary, and reproductive
Explanation:
and this is biology not physics
Q1 b name the three tiny particles which make up atoms ? a write the charge alongside each one ?
Answer:
Protons
Neutrons
Electrons.
Protons + charge(positively charged)
Neurons no charge.
Electrons - ( negatively charged).
Explanation:
Atom is the smallest unit of a matter that constitutes chemical elements.
It is composed of three particles which are protons,neutrons and electrons.
Protons is positively charged,neuron has no charge and electrons is negatively charged.
Proton and neuron are found in the nucleus while electron is found outside the neuron.
What is The distance traveled by a vehicle in 12 minutes,if it’s speed is 35km/h
Answer: 7 km
Explanation: 12 minutes is 1/5 of an hour. 35/5=7
At a camp site there are tents of 2 shades. 1 made with black fabric and the other with white fabric. Which one will you prefer for resting on a hot summer afternoon. Give reason for your choice
Answer:
Explanation:
On a hot summer afternoon the tent made up of white fabric will be preferred because white colour is a bad absorber and good reflector of heat. Hence, it will be more convenient to stay under fabric tent made of white during this season because heat will be reflected which makes shade provided by such tent to be cool and enjoyable.
While the black fabric tent will be preferred during winter because black materials are good absorber of heat and are poor reflector.
In the vertical columns of the periodic table:
Atomic weight increases from top to bottom.
Outer shell electrons increases from top to bottom.
The number of shells increases from top to bottom.
All the physical properties are identical.
Answer:
C. The number of shells increases from top to bottom
Explanation:
There are some trends about the periodic table, one of them is that in the vertical columns of periodic table, the number of shells increases from top to bottom.
From top to bottom in a periodic table, the number of electrons increases, thus more number of shells are needed to fill these electrons and the number of shells increases or we can say the atomic radius increases from top to bottom.
Hence, the correct option is "C".
i)Distinguish between different methods of charging. ii) You are provided with a positively charged gold leaf electroscope. State and explain what happens when a. a glass rod rubbed with silk is brought near the disc of electroscope. b. an ebonite rod rubbed with fur is brought near the disc of electroscope. c. an uncharged metal rod is brought near the disc of electroscope d. a glass rod rubbed with silk is rolled on the disc of electroscope.
Answer:
Explanation:
On rubbing a glass rod with silk, the electrons from the glass rod get transferred to the silk. The silk now has an excess of electrons and so is negatively-charged. On the other hand, the glass rod is deficient in electrons and hence is positively-charged.
In the above case, the silk undergoes negative electrification.
Now, when the positively charged glass rod is touched on the disc of a negatively charged gold leaf electroscope, the electrons shifts towards rod, hence amount of charge on gold leaves decreases and the divergence between the gold leaves decreases as unlike charges attract each other.
Hence, the divergence decreases when a glass rod rubbed with silk is brought near the disc of negatively charged electroscope.
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1 point
40 The diagram below shows an electrical circuit made up of a cell and three loads. The
voltage established by the cell and the resistance of each load is marked on the
diagram. Select the current flowing through the 3-ohm load.
www
1 ohm
12V
2 ohms
WWW
3 ohms
www
A. 4 amps
B. 2 amps
C. 5 amps
D. 0.25 amps
SPS106 DOK 3
Answer:
Option B. 2 A.
Explanation:
The following data were obtained from the question:
Resistance 1 (R1) = 1 Ω
Resistance 2 (R2) = 2 Ω
Resistance 3 (R3) = 3 Ω
Potential difference (V) = 12 V.
Current through the 3 Ω (I3) =?
Next, we shall determine the total resistance of the circuit.
This can be obtained as follow:
Resistance 1 (R1) = 1 Ω
Resistance 2 (R2) = 2 Ω
Resistance 3 (R3) = 3 Ω
Total resistance (R) =.?
R = R1 + R2 + R3
R = 1 + 2 + 3
R = 6 Ω
Next, we shall determine the current flowing in the circuit.
This can be obtained as follow:
From ohm's law,
Voltage (V) = current (I) x resistance (R)
V = IR
Potential difference (V) = 12 V.
Resistance (R) = 6 Ω
Current (I) =?
V = IR
12 = I x 6
Divide both side by 6
I = 12/6
I = 2 A.
Since the circuit is in series connection, therefore, the same current will flow through each resistor.
Therefore, the current through the the 3 Ω load is 2 A.
Which term describes the ability to process many things simultaneously?
O Effortful processing
O Parallel processing
O Mood congruent memory
O Flashbulb memory
O Working memory
Answer:
Parallel processing
Explanation:
It is a parallel processing because it involves the brain processing many part of problem simultaneously.
The brain natural mode of information involves performing many task .
It is also ability of the brain to simultaneously process incoming stimuli or signals of different quality. It is a part of brain's vision and divide what is seen into four major parts which are color, motion, shape, and depth.
Answer: B) Parallel processing
How much heat does 25 g of aluminum lose when cooled from 100 ° C to 20 ° C? Express your result in BTU
Answer:
1.7 BTU
Explanation:
q = mCΔT
q = (25 g) (0.9 J/g/°C) (100°C − 20°C)
q = 1800 J
q = 1800 J × (1 BTU / 1055 J)
q = 1.7 BTU
what is physics and important of physics
Answer:
Confusion
question:
is it multiple choice? or you have to write it
What is the difference between virtual images produced by concave, plane, and convex mirrors?
What does the negative sign in the value of magnification produced by a mirror indicate about
an image?
Answer:
Explanation:
A concave mirror is a curved mirror that is coated outwards. The outer part of the mirror is always coated. The nature of image formed by an object placed in front of a concave mirror can be real or virtual depending on the distance of the object on the axis from the mirror. The only time the object produces a virtual image is when it is placed between the focus and the pole of the mirror. The virtual image formed is a "MAGNIFIED and upright image"
For a convex mirror, the inner part is always coated and the nature of the image formed by the object doesn't depend on the distance between the image and the mirror. No matter where the object is placed, the image formed will always be virtual, upright and DIMINISHED. This means that magnification is always less than 1.
For a plane mirror, the nature of the image produced by a plane mirror also virtual because it is always formed behind the mirror. The size of the image formed is always THE SAME as that of the object. This means that the magnification is always equal to 1.
a) In summary, the difference between virtual images produced by concave, plane, and convex mirrors is that virtual images produced by concave mirror are MAGNIFIED, virtual images produced by plane mirror are THE SAME SIZE as that of the object and virtual images produced by convex mirrors are always DIMINISHED.
b) Magnification is defined as the ratio of the image distance to the object distance. Mag = v/u
Note that object distances are always positive, hence it is only the image distance that can either be positive or negative which in turn affects the magnification causing it to be positive or negative.
Negative image distance shows that the image is virtual while positive image distance shows that the image is real.
A negative magnification therefore shows that the nature of the image is a virtual image.
A golfer misjudges a putt and leaves her ball way short, the ball going only half of the way to the hole. If the speed of the ball leaving the putter in the first case was vo and the force of resistance due to the grass remains the same, what speed should she have given to the ball to make the original putt?
Answer:
Using
1/2mv^2 = work done by friction
work done = force x distance
lets call the force 3 N
lets call v = 3 m/s
lets call mass = 2 kg
0.5 x 2 x 3^2 = 9 J
9/3N = 3 m/s
now times 3 m/s by square root of 2 of which is 1.4142
3 x 1.4142= 4.2426 m/s
0.5 x 2 x 4.2426^2 = 18
18/2N = 9 m
A type of cuckoo clock keeps time by having a mass bouncing on a spring, usually something cute like a cherub in a chair. What force constant is needed to produce a period of 0.500 s for a 0.0150-kg mass
Answer:
the force constant k = 2.369 N/m
Explanation:
Given that:
A type of cuckoo clock keeps time by having a mass bouncing on a spring, usually something cute like a cherub in a chair.
with period T = 0.500 s and a mass of 0.0150 kg, Then the force constant can be calculated by using the formula:
[tex]\mathtt{T = 2 \pi \ \sqrt{\dfrac{m}{k} }}[/tex]
where;
T = time period
m = mass
k = force constant.
By making k the subject of the formula; we have:
[tex]\mathtt{T^2 = 4 \pi^2 (\dfrac{m}{k})}[/tex]
[tex]\mathtt{k =\dfrac{4 \pi ^2 \ m}{T^2}}[/tex]
replacing our given values , we have:
[tex]\mathtt{k =\dfrac{4 (3.142) ^2 \ \times 0.0150 }{0.5^2}}[/tex]
[tex]\mathtt{k =\dfrac{39.49 \ \times 0.0150 }{0.25}}[/tex]
[tex]\mathtt{k =\dfrac{0.59235 }{0.25}}[/tex]
k = 2.369 N/m
According to the information available in the question, the force constant is 2.37N/m.
Using the relation;
T = 2π√m/k
T = period = 0.500 s
m = mass in kilograms = 0.0150-kg
k = spring constant = ?
Making k the subject of the formula;
k = 4π^2m/T^2
k = 4 × (3.142)^2 × 0.0150/(0.500 )^2
k = 2.37N/m
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What is a potential psychological outcome of regulary playing sports
This question is incomplete because the options are missing; I found the complete question:
What is a potential psychological outcome of regularly playing sports? Select one of the options below as your answer:
a. restlessness
b. improved mood
c. depression
d. lack of energy
The answer to this question is B. Improved mood
Explanation:
Practicing a sport regularly has multiple positive effects including physical and psychological benefits. In the case of psychological effects, this includes an improved mood, this is because practicing a sport reduces stress significantly and it is often associated with positive emotions such as motivation, confidence, or pride. Moreover, interacting with others in group sports allow individuals to positively interact with others, which contributes to a better mood. Thus, one potential psychological outcome of playing sports is an improved mood.
what is a hypothesis reffered to as after being verified by a large number or independent experiments
Answer:
The hypothesis may or may not be true and needs to be tested. It might be the answer to the problem. Hence, it must be tested thoroughly. When these predictions are tested again and again in independent scientific experiments and gets verified, the hypothesis is converted into a scientific theory.
Once a scientist has made a hypothesis, what would they typically do next? (2 points)
a
Analysis
b
Testing
C
Research
d
Sharing
Answer:Testing
Explanation:Once a scientist has made a hypothesis, what would they typically do TESTING nextn
Once a scientist has made a hypothesis, they would typically do testing, therefore the correct answer is option B
What is the scientific claim?Scientific claims are statements made in science based on an experiment.
These Scientific claims are backed by the experimental data and their true results obtained from scientific investigation and experimentation.
When a scientist performs a fair test is one in which all other circumstances are maintained while just one variable is changed at a time.
Scientists frequently discover that their hypotheses and predictions were not supported by the results of their experiments. In these situations, they will communicate the findings of their experiment before revising their original hypotheses and predictions in light of the new knowledge they have gained.
The right response is option B because once a scientist has made a theory, they usually do testing.
Learn more about the scientific claims, here
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Convert 85 cm/min to m/s.
Explanation:
meter=100cm
cm=10^-2 m
min=60 sec
0.0141666667 m / s
The conversion of 85 cm/min would be 0.0133 m/s
What is Velocity?The total displacement covered by any object per unit of time is known as velocity. It depends on the magnitude as well as the direction of the moving object.
As given in the problem position-time graph of an object.
As we know that slope of the position time curve represents the velocity of the object
As given in the problem we have to convert 85 cm/min to m/s.
Let us first convert the displacement in cm to meters
100 cm = 1 m
1 cm = 1/100 m
85 cm = 85×1/100 m
= 0.85 m
similarly, convert time given in minutes to the seconds
1 min = 60 s
velocity = displacement /time
velocity = 0.85 / 60 m/s
=0.01333 m/s
Thus, we converted 85 cm/m into 0.0133 m/s
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Which instrument is used to measure the height of a 20 litre jerrican
tape measure?
Hope that helped!!! k
instrument is used to measure is Tape measure
what is the meaning of energy
Answer:
[tex]\boxed{\mathrm{view \ explanation}}[/tex]
Explanation:
Energy is the capacity of an object to do work. Energy must be transferred to an object in order to do work. The SI unit of energy is Joules (J).
Answer:
See below
Explanation:
Energy is the "capacity/ability to do work". If the body has the ability to do work, we mean that the body possesses energy.
Units:
Energy is measured in Joules (J)
Types:
The two "main" types of energy are:
1) Kinetic Energy
2) Potential Energy
A train travels southwest from point A to point B through the Arizona desert at 55 mi/h. How far will the train travel six-and-a-half hours?
Explanation:
Distance = speed × time
d = (55 mi/hr) (6.5 hr)
d = 357.5 mi
what is the best defintion of efficency
Answer: Efficiency signifies a peak level of performance that uses the least amount of inputs to achieve the highest amount of output.
Explanation: It minimizes the waste of resources such as physical materials, energy, and time while accomplishing the desired output.
Answer:
The efficiency of a simple machine is defined as the ratio of useful work done by the machine ( output work) to the total work out into the machine ( input work).
Explanation:
EfficiencyIf a machine overcomes a load ' L ' and the distance travelled by the load is 'Ld' , the work done by the load is L× LD. It is also called output work or useful work.
Therefore, [tex] \boxed{Output \: work \: = L \: \times \: Ld}[/tex]
Likewise, The effort applied to overcome the load is 'E' and the distance covered by effort is 'Ed' , the work done by effort is E × Ed. It is also called input work.
Therefore, [tex] \boxed{Input \: work = E \times Ed}[/tex]
The efficiency of a simple machine is defined as the ratio of output work to the input work .
Therefore, [tex] \boxed{Efficiency ( η)= \frac{outpt \: work}{input \: work} \times 100\%}[/tex]
Efficiency is expressed in percentage. It is a ratio of two works. A machine is never 100% efficient. It is because no machine is friction free and due to friction, some of the input energy is wastes in the form of heat energy.
[tex] \mathrm{Hope \: I \: helped!}[/tex]
[tex] \mathrm{Best \: regards!}[/tex]
Describe what happens to water waves when they strike a flat surface?
Answer:
In this case reflection occurs.
Explanation:
This happens when they bounce on objects that they can not pass through.
Hope it helps
okay.
When using science to investigate physical phenomena, which characteristic of the event must exist?
predictable
measurable
provable
readable
READ NEXT SECTION
ASK FOR HELP
The correct answer is B. Measurable
Explanation:
The use of science to investigate a phenomenon implies using measurements and observations to better understand a phenomenon or test a hypothesis. Moreover, science focuses on natural phenomena that can be objectively studied through measurement instruments such as a thermometer, balance, hydrometer, etc.
In this context, for a phenomenon to be studied by science this needs to be measurable because the use of precise instruments as wells as numbers allow scientist to analyze and understand a phenomenon. Moreover, phenomena that depend on personal perspectives and cannot be measure is considered as non-scientific.
A 1000 kg car developed a snag and is standing in the middle of a road. The driver and a help pulled it with two ropes respectively with forces 200√2 N 45° east of south and 400N 30° north of east. Assuming negligible friction, find the acceleration of car
Answer:
Acceleration = 0.1464 m/s^2
Explanation:
From the question, the parameters given are:
Mass m = 1000 kg
The driver and a help pulled it with two ropes respectively with forces 200√2 N 45° east of south and 400N 30° north of east
Find the resultant force along the x axis.
(400 × cos30) - (200√2 × cos45)
346.4 - 200 = 146.4 N
therefore, the resultant force = 146.4N
The formula to use for the acceleration of the car is
F = ma
Where
F = resultant force
M = mass of the car
a = acceleration of the car
Substitute f and m into the formula
146.4 = 1000 × a
Make a the subject of formula
a = 146.4 / 1000
a = 0.1464 m/s^2
Therefore, the car accelerate at 0.1464 m/s^2
