If it takes cool air and passes it through the heat source using a fan or blower, the type of heat transfer is convection heat transfer.
What is heat transfer by convection?
Convection is the transfer of heat from one place to another due to the movement of fluid.
During heat transfer by convection, cold air replaces hot risen air.
Thus, if it takes cool air and passes it through the heat source using a fan or blower, the type of heat transfer is convection heat transfer.
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16/07/2021 23
question 9 of 10
homework
which movement will require the greatest amount of work to be
done?
this activity is
a force of 10n moving an object a distance of 3.0 m
b*
assessment
percentage
a force of 10n moving an object a distance of 5.0m
a force of 15n moving an object a distance of 3.0m
c attempts
a force of 15n moving an object a distance of 5.0m
D. The movement that will require the greatest amount of work to be
done is a force of 15n moving an object a distance of 5.0m (75 J).
What is work done?Work is said to be done when an applied force moves an object over a given distance.
W = Fd
where;
F is the applied forced is the displacement of the objectA force of 10n moving an object a distance of 3.0 mW = 10 x 3 = 30 J
A force of 10n moving an object a distance of 5.0mW = 10 x 5 = 50 J
A force of 15n moving an object a distance of 3.0mW = 15 x 3 = 45 J
A force of 15n moving an object a distance of 5.0mW = 15 x 5 = 75 J
Thus, the movement that will require the greatest amount of work to be
done is a force of 15n moving an object a distance of 5.0m (75 J).
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How does a person standing on the ground correctly explain why you, sitting on the left side of a slippery back car seat, slide to the right when the car makes a high speed left turn
Answer:
if the car is traveling north, the person is also traveling north,
If the car turns to (left) to the west, the person will still tend to travel to the north and will slide to the right (north) on a slippery car seat.
With what speed must a ball be thrown vertically from ground level to rise to a maximum height of 50 m
The speed with which the ball must be thrown vertically from ground level to rise to a height of 50 m is 31.305 m/s.
Given values:
Maximum height reached from ground level, h_max = 50 m
Final velocity of the ball, v = 0 m/s
Calculation of initial speed of the ball:
Step 1:
Using Newton's third equation of motion, we get:
v² = u² + 2as
where, v is the final velocity of ball
u is initial velocity of the ball
a is acceleration of ball
s is the maximum height attained by the ball
Step 2:
Here, the acceleration of the ball will be given as:
a = -g
= -9.8 m/s²
where, g is acceleration due to gravity
Applying this value in above equation we get:
v² = u² - 2gh_max
Re-arranging above equation, we get:
u² = v² + 2gh_max
u =√(v² + 2gh_max)
Step 3:
Applying values in above equation we get:
u =√((0 m/s)² + 2(9.8 m/s²)(50 m)
=√980
= 31.305 m/s
Therefore, the speed with which the ball must be thrown from ground level is 31.305 m/s in order to reach a maximum vertical height of 50 m.
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A new ride being built at an amusement park includes a vertical drop of 70.0 meters. Starting from rest, the ride vertically drops that distance before the track curves forward. The velocity at the bottom of the drop is 12.0 m/s and the mass of the cart and passengers is 3.5 x 104 kg.
a. Calculate the potential, kinetic and total energy at the top.
b. Calculate the potential, kinetic and total energy at the bottom.
c.Is the total energy at the top equal to the total energy at the bottom? Justify your observation.
The potential, kinetic and total energy at the top are 2.38 x 10⁷ Joule, 0 Joule, 23.8 x 10⁶ Joule respectively and the potential, kinetic and total energy at the bottom are 0 Joule, 2.448 x 10⁶ Joule, 2.448 x 10⁶ Joule respectively. moreover the total energies are not same as not all potential energy converting into Kinetic energy of vertically drop of ride as the ride moves straight afterwards so that also need some energy which is again coming from potential energy.
Energies at the top:-
Potential energy = mgh
Potential energy = 3.4 x 10⁴ × 10 × 70 Joule
Potential energy = 2.38 x 10⁷ Joule
Kinetic Energy = (1/2) mv²
Kinetic Energy = (1/2) × 3.4 x 10⁴ × 0²
Kinetic Energy = 0 Joule
Total Energy = Potential Energy + Kinetic Energy
Total Energy = ( 23.8 x 10⁶ Joule ) + ( 0 Joule )
Total Energy = 23.8 x 10⁶ Joule
Energies at the bottom:-
Potential energy = mgh
Potential energy = 3.4 x 10⁴ × 10 × 0 Joule
Potential energy = 0 Joule
Kinetic Energy = (1/2) mv²
Kinetic Energy = (1/2) × 3.4 x 10⁴ × 12²
Kinetic Energy = 2.448 x 10⁶ Joule
Total Energy = Potential Energy + Kinetic Energy
Total Energy = ( 0 Joule ) + ( 2.448 x 10⁶ Joule )
Total Energy = 2.448 x 10⁶ Joule
The total energies are not the same since not all potential energy is converted into Kinetic energy of the vertical drop of the ride as the ride travels straight thereafter thus that also requires some energy which is again derived from potential energy.
So we have calculated the potential, kinetic and total energy at top and bottom both, and also stated the reason of why total energy at the top is not equal to the total energy at the bottom.
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What is the instantaneous velocity of a freely falling object 14 s after it is released from a position of rest
The instantaneous velocity of the object is 137.2 m/s along the downward direction.
Instantaneous velocity: The velocity of an object at a particular instant of time is called the instantaneous velocity.
Note: The y-axis is taken along the upward direction so acceleration due to gravity will be negative.
Any object that is falling freely is acted upon by gravity. The first equation of motion gives the relationship between initial velocity, the velocity at time t, time, and acceleration. The equation is,
v=u+at
where v is the velocity at time t, u is the initial velocity, t is the time, and g is the acceleration due to gravity. Since the object starts from rest, its initial velocity is zero.
For the given case, u=0, a=-9.8 m/s^2 and t=14 s. Put the values in the equation to get the instantaneous velocity of the object at t=14 s.
v=0+(-9.8)(14)
v=-137.2 m/s
The negative sign indicates the object is falling downward.
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A steel needle when placed carefully on water can be made to float.when the detergent is added to the water it sink.explain the observation
Answer:
The surface tension of plain water can cause a needle to float.
Evidently, the addition of detergent to the water reduces the surface tension of the liquid causing the needle to sink.
When we add detergent to water, the surface tension of water immediately decreases, then the surface tension cannot balance the blade and it will sink.
What is Surface tension?Surface tension is defined as the phenomenon that occurs when the surface of a liquid is in contact with another phase which may also be a liquid. Liquids obtain the least possible surface area while the surface of the liquid behaves like an elastic sheet.
Surface tension depends not only on the forces of attraction between particles within a given liquid but also on the forces of attraction of the solid, liquid or gas in contact with it where energy is responsible for the occurrence of surface tension, which can be thought of as approximately equal to the work or energy required to remove a surface layer of molecules in a unit area.
When we add soap to water, the surface tension of the water decreases to the point where the surface tension is no longer strong enough to "float" the needle.
Thus, when we add detergent to water, the surface tension of water immediately decreases, then the surface tension cannot balance the blade and it will sink.
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Two children are riding on a merry-go-round. Child A is at a greater distance from the axis of rotation than child B. Which child has the larger tangential speed
Answer: Two children are riding on a marry-go-round. Child A is at a greater distance from the axis of rotation than child B. Thus, the child A, located at a greater distance from the axis of rotation have a larger tangential speed.
Explanation: To find the correct answer we have to know more about the Angular velocity of a rotating body.
What is the angular velocity?In rotational motion, the angular velocity ω can be defined as, the change in angular displacement(Ф) per unit time (t).It's the revolution per second.The angular velocity can be expressed in terms of the tangential velocity as well as the radius of the circular path as,[tex]w=V/r[/tex]
How to solve the question?We know that the expression for the tangential velocity as,[tex]V=wr[/tex]
In the question, for both the child, the value of w will be same. Thus, the only quantity that depends on the tangential velocity will be the distance from the axis of rotation.The maximum will the value of V, if the r maximizes.Thus, child A with greater distance will have larger tangential speed.Thus, we can conclude that, child A with greater distance will have larger tangential speed.
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why are experiments often performed in labs?
Answer:
experiments provide course effective means of quantitative process kind of examing the bounds of theory is specially when the Nolan reality is important analysis
Explanation:
regardless of such topic the purpose of laboratory experiment is to test theory occurs by focusing on one server predictive elements of the theory is isolating the influence of elements on outcomes
A baseball with a mass of 0.145 kilograms collides with a bat at a velocity of 44 meters/second. the ball bounces off the bat with a speed of 49 meters/second in the opposite direction. what is the impulse? a. 4.32 newton∙seconds b. 7.25 newton∙seconds c. 8.23 newton∙seconds d. 9.42 newton∙seconds e. 13.5 newton∙seconds
The impulse is 13.5 N-s.
As we know that impulse is a sudden force acting on a body for a short time interval is called Impulse.
Δp = FΔt
Mathematically, the change in momentum will equal impulse.
Δp = mΔv
→ Δp = 0.145(49-(-44))
→ Δp = 0.145(93)
Δp = 13.5 Newton-second
Thus, option (e) is correct.
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If a baseball pitcher throws a fastball at a horizontal speed of 160 km/h, how long does the ball take to reach home plate 18.4 m away
Answer: 0.000115 seconds
Explanation: how I got this is by first converting the meters to kilometers then I had 160 km/h and 0.0184 km away so then you do 0.0184 divided by 160 (0.0184 / 160) and get 0.000115 seconds.
Nora's hair dryer is 64% efficient. If 1000 J of energy is supplied to the hair dryer, how much energy will it transfer usefully to Nora's hair?
Answer:
The hair dryer will transfer 640J of energy usefully to Nora’s hair.
Explanation:
Efficiency = output/input × 100%
Data
Efficiency = 64%
Energy input = 1000J
Energy output = ?
Efficiency = Energy output/Energy input × 100%
64% = Energy output /1000J × 100%
Divide both sides by 100%
0.64 = Energy output/1000J
Energy output = 0.64 × 1000J
Efficiency output = 640J
Therefore the hair dryer will transfer 640J of energy usefully to Nora’s hair.
During a process, 2 kJ of work are done on a system, and 3 kJ of heat are given away by the system. What is the change of internal energy of the system
The change in the internal energy of the system is increased by 1 Kj.
Determination of the internal energyAccording to the first law of thermodynamics,
Energy can only be changed in form; it cannot be generated or destroyed, according to the basic rule of thermodynamics. External work or heat exchange over the barrier are all examples of energy transfer for any system. These result in a change in the control volume's energy reserves.Therefore, Δ∪=q+w
[Δ∪= change of internal energy; q=heat; w=work]
Provided,
q= -3Kj (as heat is given away)
w= +2Kj (work done in the system is positive)
So, Δ∪= -3 + (+2) Kj
⇒Δ∪= -1 Kj
Therefore the internal energy of the system is increased by 1 kj.
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An ice skater performs a pirouette (a fast spin) by pulling in his outstretched arms close to his body. What happens to his moment of inertia about the axis of rotation
Moment of inertia decreases about the axis of rotation.
The term "moment of inertia" refers to the quantity that describes how a body resists angular acceleration and is calculated by multiplying each particle's mass by its square of distance from the rotational axis.
Means,
I=mr² where,
I= Moment of inertia
m= mass of particle
r= distance of the particle from the axis of rotation.
So, Moment of inertia is directly proportional to the square of the distance from the axis of rotation.
I ∝ r²
As the distance of body from the axis of rotation increases, moment of inertia also increases and vice versa.
So, that's why when an ice skater performs a pirouette (a fast spin) by pulling in his outstretched arms close to his body , then he/she will decrease his/her distance from the axis of rotation.
That's why moment of inertia decreases about the axis of rotation.
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What type of system would allow light and air to enter and exit? A. Connected
B. Closed C. Isolated D. Open
Answer:
An open system.
Explanation:
An isolated system allows the exchange of neither energy nor matter with the surroundings. A closed system allows the exchange of energy, but not matter. An open system allows the exchange of both energy and matter.
Notice that in this question, light (electromagnetic wave) is a form of energy. The entry and exit of light allows this system to exchange energy with its surroundings- just as how the earth receives energy from the sun. Additionally, this system could exchange energy with its surroundings through the exchange of matter (in particular, air) with its surroundings.
Thus, the system in this question is an open system.
According to dr. Ed coyle, the fda does not regulate dietary supplements. When is it acceptable for a high school athlete to include dietary supplements in their diets?.
Athletes that energy drinks are not appropriate for hydration or as dietary supplements.
When should athletes use supplements?Vitamins and minerals are recommended when an athlete has low blood values, a medical condition that may lead to poor absorption of nutrients, or other potential nutrition/eating challenges.
As per the question
FDA doesn't regulate dietary supplements
Dietary supplement companies must ensure their products are safe before marketing and comply with other labeling and quality requirements, such as good manufacturing practices.
The FDA inspects facilities for compliance and monitors adverse event reports.
Dietary supplements should be used only upon the advice of one’s health care provider for health-related reasons – not for the purpose of gaining a possible competitive advantage.
They recommend that coaches, athletic directors, and other school personnel develop strategies that address the prevalence and growing concerns of using dietary supplements. Such strategies may include conversations with athletes and their parents about the potential dangers of dietary supplement use.
Athletes should be encouraged to pursue their athletic goals through hard work, appropriate rest and good nutrition, not unsubstantiated dietary shortcuts.
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Different asteroids reflect different percentages of the light falling on them. This is due to the fact that they have different:
Due to the Composition, different asteroids reflect different percentages of the light falling on them.
What are Asteroids:
Asteroids are small, rocky objects that orbit the Sun. Although asteroids orbit the Sun like planets, they are much smaller than planets. Asteroids are generally made up of rocky material, metals and their size are large in comparison to comets. Asteroid belt is found between Jupiter and Mars.Composition of Asteroids:
Most of the asteroids in the Main Belt are made of rock and stone. The remaining asteroids are made up of a mix of these, along with carbon-rich materials. Some of the more distant asteroids tend to contain more ices.We determine reflectivity of asteroids by comparing the brightness of light in the visible spectrum to the brightness of light in the infrared spectrum. The light shining from asteroids is reflected sunlight.
Hence we can say that,
Due to the Composition, different asteroids reflect different percentages of the light falling on them.
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A rocket takes off from Earth's surface, accelerating straight up at 31.2 m/s2. Calculate the normal force (in N) acting on an astronaut of mass 90.4 kg, including her space suit.
The normal force is 2820.48N in the negative y direction.
According to Newton's second law of motion,
Force = mass × acceleration
F = m×A
Note that rocket takes off from Earth's surface, accelerating straight up at 31.2 m/s² .
The rocket accelerates upwards, hence the acceleration will be negative because it defies gravity's law (it keeps going into space without coming down)
Acceleration of the rocket = -31.2m/s²
Mass of the astronaut = 90.4kg
Normal force acting on the astronaut = -31.2 × 90.4kg
= -2820.48N
Therefore, the normal force is 2820.48N in the negative y direction.
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The Viking spacecraft observed several features on Mars that, at first, appeared to be artificially crafted. After further study the features were primarily naturally occurring phenomena resulting from _____ on the Martian surface.
Answer:
Erosion of the surface of Mars.
Explanation:
The surface of Mars have features which were formed as a result of the erosion of the surface of the Mars.
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If a car moving at 15 m/s skids to a stop after 20 m, how far will it skid if it is moving at 45 m/s? Assume that the braking force is constant. Group of answer choices 50 m 20 m 180 m 90 m 120 m
The car will skid at 80m
As we know that In mechanics, acceleration is the rate of change of the velocity of an object with respect to time.
It is a vector quantity
The velocity is the distance covered by an object per unit time
Given
Initial velocity (u) = 15m/s
Final Velocity (v) = 0m/s
Distance (s) = 20 m
Deceleration (a) =?
Now we know that ,
v² = u² + 2as
Substituting the value
0² = 15² + (2)*(a)*(20)
0 = 225 + 40a
Collecting the like terms
0 – 235 = 40a
–225 = 40a
To find the value of a divide both side 40
a = –225 / 50
a = –5.625 m/s²
Determination of the distance
Deceleration (a) = –5.625 m/s²
Initial velocity (u) = 30 m/s
Final velocity (v) = 0 m/s
Distance (s) =?
v² = u² + 2as
0² = 30² +(2 × –5.625 × s)
0 = 900 – 11.25s
Collecting like terms
0 – 900 = –11.25s
–900 = –11.25s
To find the value of s divide both side by –11.25
s = –900 / –11.25
s = 80 m
Hence the car will skid 80 m
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A 2280 kg car, moving at 24.2 m/s, runs into a car that has a mass of 2180 kg
and is moving at 15.3 m/s in the same direction. The cars stick together after
the collision. Assuming momentum is conserved, what is their final velocity?
OA. 18.6 m/s
OB. 17.2 m/s
O C. 19.8 m/s
OD. 16.7 m/s
Answer:
The answer is C.19.8 m/s because it's their common velocity after the collision of the two cars.
Explanation:
Hello !
look at the attachment above ☝️ and if you have any questions you're welcome.
A ball of mass 200 g rolls along the ground at a speed of 5.2 m/s. Calculate the kinetic energy of the ball. Give your answer to two significant figures.
Answer:
Kinetic Energy = 2.7J
Explanation:
Conversion :
200g = 0.2kg
Kinetic Energy = ½ × mass × (velocity)²
Kinetic Energy = ½ × 0.2kg × (5.2m/s²)
Kinetic energy = ½ × 0.2kg × 27.04m²/s²
Kinetic Energy = 2.7J
The right answer is "2.7 J"
Answer explanation:
Remember to convert grams to kilograms first by dividing by 1000.
Kinetic energy
= 1/2 × mass × speed2
= 1/2 × 0.2 kg × (5.2 m/s)^2
= 2.7 J (to 2 sig. fig.)
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A key falls from a bridge that is 43 m above the water. It falls directly into a model boat, moving with constant velocity, that is 17 m from the point of impact when the key is released. What is the speed of the boat
The speed of the boat is 4 m/s.
The system for pace is speed = distance ÷ time.
To work out what the devices are for pace, you want to understand the gadgets for distance and time. In this case, distance is in meters (m) and time is in seconds (s), so the gadgets could be in meters according to second (m/s).
To resolve for speed or price use the components for pace, s = d/t which means that pace equals distance divided through time.
The pace is a manner of measuring how quickly something is transferring or being performed, or something moving speedily. An example of speed is a vehicle being driven 45 miles in keeping with the hour. An instance of velocity is a person cleaning a room in 10 minutes. An example of velocity is how quickly a jaguar runs.
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A hot metal ball is hung in an oven that is maintained at 700 K; and it cools. When the temperature of the ball is 950 K, it is losing heat at a rate of 0.15 J/min. At what rate will the ball lose heat when the ball reaches 820 K
Answer:
At 820 K, the object lose heat at the rate of 0.072 J/min.
Explanation:
By using Newton's cooling law, the formula to calculate the rate of cooling R is,
R=-k(T-To)
where k is a constant, T is the temperature of the object and To is the temperature of the surrounding.
At T=950 K, R=0.15 J/min and To=700 K,
Therefore, 0.15=-k(950-700)
k=0.15/250 J/K min.
At T=820 K,
R=-(0.15 / 250)*(820-700)
R=-0.072 J/min
Therefore the rate of heat loss at T=820 K is 0.072 J/min.
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Vector A has a magnitude of 623. What are its west and north components?
A
The problem cannot be solved because vectors at 90 degree angles to the reference system do not have components.
B
0 south, 0 east
C
623 west, 0 north
D
623 north, 0 west
Answer:
D) 623 N
Explanation:
The vectors' direction is in the North And when we try to take Y and X components Cos(90°) is Zero ... So the X (West) component will be zero
Write an argument of any one
Do you think parallel universes exist?
or
Do you think portals exist?
If the plates are pulled twice as far apart, but are kept connected to the battery, the electric field between the plates will be
Electric field between two parallel plates will be halved as it was before.
What is the electric field between two plates:
The electric field lines of two parallel plates can be represented by straight lines perpendicular to both plates surfaces while carrying arrows that point from +Q plate A toward -Q plate B.
we know that,
The electric field between plates:
E=V / d
where,
V is battery voltage
d is separation distance between plates.
now If the plates are pulled twice as far apart, but are kept connected to the battery,
the separation distance becomes,
d' = 2d
so the new electric field will be:
E' = V / d'
substituting the values,
E' = V / ( 2d )
E' = 1/2 ( V /d )
E' = 1/2 E
hence we can conclude that
Electric field between plates will be halved as it was before.
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Consider a blimp that can be approximated as a 3-m diameter, 8-m long ellipsoid and is connected to the ground. On a windless day, the rope tension due to the net buoyancy effect is measured to be 120 N. Determine the rope tension when there are 50 km/h winds blowing along the blimp (parallel to the blimp axis).
Step 1 of 6
Diameter of the blimp,
Length of the blimp,
Rope tension,
The velocity of the wind,
Step 2 of 6
The drag force acting on the blimp can be calculated using the formula given below,
(1)
Where, is the drag coefficient is the density of air.
A is the frontal area of the blimp.
V is the velocity of the wind.
Step 3 of 6
The frontal area of the parachute,
Here,
Substitute the value in the above equation.
The drag coefficient for the balloon is,
Step 4 of 6
From the table properties of air,
The density of air at 1atm pressure and is,
The velocity of air,
Step 5 of 6
Now, substitute all the known values in equation (1)
Step 6 of 6
Now, rope tension is the sum of rope tension due to the buoyancy effect and the force due to the wind blowing.
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Inez uses hairspray on her hair each morning before going to school. The spray spreads out before reaching her hair partly because of the electrostatic charge on the hairspray droplets. If two drops of hairspray repel each other with a force of 9 x 10^-9 N at a distance of 0.07 cm ( 7 x 10^ -4 m), what is the charge on each of the equally charged drops of hairspray?
Please show the steps as well. Written out, if possible.
The charge on each of the equally charged drops of hairspray willl be 7 × 10 ⁻¹³ C
What is Columb's law?The force of attraction between two charges, according to Coulomb's law, is directly proportional to the product of the charges and inversely proportional to the square of the distance between them.
Similar charges repel each other, whereas charges that are opposed attract each other.
Given data;
Electric force,F = 9 × 10 ⁻⁹ N
Distance between charges,d = 7 × 10⁻⁴ m
Chrge,q₁ = q₂ =q C
From Columb's law;
[tex]\rm F = K \frac{q_1q_2}{d^2} \\\\ 9 \times 10^{-9} = 9 \times 10^9 \frac{q^2}{(7 \times 10^{-4})^2} \\\\ q^2 = 4.9 \times 10^{-25} \\\\ q = 7 \times 10^{-13} \ C[/tex]
Hence the charge on each of the equally charged drops of hairspray willl be 7 × 10 ⁻¹³ C
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A dentist holds a small mirror 1.9
cm from a patient’s tooth. The image
formed is upright and 5
times as largeas the object. (a) Is
the image real or virtual? (b) What
is the focal length of the mirror? Is it
concave or convex? (c) If the mirror
is moved closer to the tooth, does the
image get larger or smaller? (d) For
what range of object distances does
the mirror produce an upright image?
Answer:
follow me for legitimate answer… oh? U don’t like the feeling of people stealing ur points huh?! Well theirs a taste of your own medicine
Explanation:
What was the initial speed of a car if its speed is 40 m/s after 5 seconds of accelerating at -4 m/s²?
A. 50 m/s
B. 60 m/s
C. 25 m/s
D. 20 m/s
Answer:
[tex]\huge\boxed{\sf V_i=60 \ m/s}[/tex]
Explanation:
Given Data:Final speed = [tex]V_f[/tex] = 40 m/s
Time = t = 5 s
Acceleration = a = -4 m/s²
Required:Initial velocity = [tex]V_i[/tex] = ?
Formula:[tex]\displaystyle a = \frac{V_f-V_i}{t}[/tex]
Solution:Put the givens in the above formula
[tex]\displaystyle -4=\frac{40 - V_i}{5} \\\\Multiply \ -5 \ to \ both \ sides\\\\-4 \times 5 = 40 - V_i\\\\-20 =40-V_i\\\\Subtract \ 40 \ to \ both \ sides\\\\-20-40=-V_i\\\\-60\ m/s=-V_i\\\\60 \ m/s = V_i\\\\V_i=60 \ m/s\\\\\rule[225]{225}{2}[/tex]