what is simple definition of democracy
it's a form of government where people elect their representatives
Answer:
The word democracy itself means rule by the people.
44.7
When Xavier places his hands near a light bulb, he notices that certain areas around the light bulb are warmer than
others. Which best explains this?
The areas to the sides of the light bulb are warmest because of conduction,
O The areas to the sides of the light bulb are warmest because of convection,
The area directly above the light bulb is warmest because of conduction,
The area directly above the light bulb is warmest because of convection.
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Answer:
The area directly above the light bulb is warmest because of convection.
Explanation:
if all the sides of the bulb are equally close to the light source inside the bulb, all area of the bulb would be equally heated by conduction. however, convection heating mainly heats up the surface above the light source. in convection heating, the air above the surface of the light source get heated by the light source and expands, casuing it to be less dense and rise to the top of the bulb. colder denser air at the top of the bulb sink to the light source adn gain heat and expands, becoming less dense. this process repeats and the surface above the light source becomes the warmest due to convection heating
Which of the following statements regarding the warming of the troposphere (i.e., the lower atmosphere) are TRUE (choose all that apply):
a. Conduction only warms the shallow layer of air within a few centimeters of the ground
b. The troposphere is heated mainly from above
c. Atmospheric gases do not readily absorb solar radiation
d. The troposphere is heated mainly by direct molecule-to-molecule contact
e. Condensation of water vapor plays a role in heating the lower atmosphere
f. Oxygen and nitrogen readily absorb and emit terrestrial radiation
g. Convection distributes heat vertically
Answer: • Conduction only warms the shallow layer of air within a few centimeters of the ground
• Atmospheric gases do not readily absorb solar radiation
• Condensation of water vapor plays a role in heating the lower atmosphere.
• Convection distributes heat vertically
Explanation:
The statements regarding the warming of the troposphere that are true include:
• Conduction only warms the shallow layer of air within a few centimeters of the ground
• Atmospheric gases do not readily absorb solar radiation
• Condensation of water vapor plays a role in heating the lower atmosphere.
• Convection distributes heat vertically.
Therefore, the correct options are A, C, E and G.
• Conduction only warms the shallow layer of air within a few centimeters of the ground
• Atmospheric gases do not readily absorb solar radiation
• Condensation of water vapor plays a role in heating the lower atmosphere.
• Convection distributes heat vertically
What is troposphere?The lowest layer of the atmosphere of the earth is the troposphere. Most of the mass (about 75-80%) of the atmosphere is in the troposphere.
Most types of clouds are found in the troposphere, and almost all weather occurs within this layer.
The statements regarding the warming of the troposphere that are true include:
• Conduction only warms the shallow layer of air within a few centimeters of the ground
• Atmospheric gases do not readily absorb solar radiation
• Condensation of water vapor plays a role in heating the lower atmosphere.
• Convection distributes heat vertically.
Thus a,c,e,g are the correct statements regarding the warming of the troposphere
To know more about Troposphere follow
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If a piece of an object is dropped down vertically is the moment of inertia gonna be 0? And why?
Please answer I really need this!!
Answer:
The object is dropped, we know the initial velocity is zero. Once the object has left contact with whatever held or threw it, the object is in free-fall. Under these circumstances, the motion is one-dimensional and has constant acceleration of magnitude g.
No so sure
Explanation:
Hope it helps
In another version of the "Giant Swing", the seat is connected to two cables as shown in the figure (Figure ), one of which is horizontal. The seat swings in a horizontal circle at a rate of 39.3 rev / m * i * n
If the seat weighs 268 N and a 896-N person is sitting in it, find the tension in the horizontal cable
If the seat weighs 268 N and a 896-N person is sitting in it, find the tension in the inclined cable
Answer:Solution to 47E Step 1 Angular velocity of the swing=32rpm Weight of the seat =255N Weight of the person =825N Total weight =255+825=1080N Radius =7.5m
Explanation:
Three identical boxcars are coupled together and are moving at a constant speed of 28.0 m/sm/s on a level, frictionless track. They collide with another identical boxcar that is initially at rest and couple to it, so that the four cars roll on as a unit. Friction is small enough to be neglected.
Required:
a. What is the speed of the four cars?
b. What percentage of the kinetic energy of the boxcars is dissipated in the collision?
c. What happened to this energy?
Answer:
A) v = 21 m /s
B) 25%
C) ) on collision, this energy in the question appears in the form of the following namely; sound energy, heat energy etc
Explanation:
A) Let m be the mass of any of the cars
Thus:
mass of the three cars = 3m
Formula for kinetic energy = ½mv²
Thus, Kinetic energy of 3 identical and coupled cars = ½ x 3m x 28² = 1176 m
KE = 1176 m
Now mass of 4 coupled cars together = 4m
From conservation of linear momentum, we can find the speed of the four cars. Thus;
m1v1 = m2v2
We are told that the 3 coupled moved together with a speed of 28 m/s
Thus;
4m × v = 3m × 28
v = 3m x 28 / 4m
v = 21 m /s
B) from earlier, we saw the formula for kinetic energy. Thus, kinetic energy with of mass of 4 coupled cars together. Thus;
K = ½ x 4m x 21²
K = 882m
Loss of kinetic energy
ΔK = 1176 m - 882 m
ΔK = 294 m
Therefore, percentage of loss is;
%loss = (294 / 1176 ) x 100
%loss = 25 %
C) on collision, this energy in the question appears in the form of the following namely; sound energy, heat energy etc
for the long life cells we have to connect them in ____ combination
Answer:
Parallel combination.
for the long life cells we have to connect them in parallel combination
hope it is helpful to you
A house has well-insulated walls. It contains a volume of 105 m3 of air at 305 K.
Consider heating it at constant pressure. Calculate the energy required to increase the temperature of this diatomic ideal gas by 0.7
Answer: [tex]85.46\ kJ[/tex]
Explanation:
Given
Volume of air [tex]V=105\ m^3[/tex]
Temperature of air [tex]T=305\ K[/tex]
Increase in temperature [tex]\Delta T=0.7^{\circ}C[/tex]
Specific heat for diatomic gas is [tex]C_p=\dfrac{7R}{2}[/tex]
Energy required to increase the temperature is
[tex]\Rightarrow Q=nC_pdT\\\\\Rightarrow Q=n\times \dfrac{7R}{2}\times \Delta T\\\\\Rightarrow Q=\dfrac{7}{2}nR\Delta T\\\\\Rightarrow Q=\dfrac{7}{2}\times \dfrac{PV}{T}\times \Delta T\quad [\text{using PV=nRT}][/tex]
Insert the values
[tex]\Rightarrow Q=\dfrac{7}{2}\times \dfrac{1.01325\times 10^5\times 105}{305}\times 0.7\\ \text{Assuming air pressure to be atmospheric P=}1.01325\times 10^5\ N/m^2\\\\\Rightarrow Q=0.8546\times 10^5\\\Rightarrow Q=85.46\ kJ[/tex]
The colors that make up white light are called what?
Answer:
The ROYGBIV
Explanation:
R - red
O - orange
Y - yellow
G - green
B - blue
I - indigo
V - violet
A balloon pops, making a loud noise that startles you. What kind of energy best describes this experience?
A. Thermal Energy
B. Sound Energy
C. Gravitational Energy
D. Radiant Energy
How would an observer on train A, which is moving at nearly the speed of light, view a clock on train B, which is moving at the same speed and in the same direction?
A. The clock on train B would appear narrower and run more slowly.
B. The clock on train B would appear to be the same width and to run at the same rate. C. The clock on train B would appear narrower and run faster.
D. The clock on train B would appear wider and run more slowly.
Answer:
B.
Explanation:
If both train A and train B are moving in the same direction and the exact same speed then from an observer's viewpoint within either train everything would seem as though it is not moving. Therefore, the clock on train B would appear to be the same width and to run at the same rate. In order for this to be the case the speed of both trains would need to be exactly the same, any difference in speed will cause the clock on the opposite train to appear distorted and run either faster or slower depending on the speed of the train you are on.
Answer:
The trains are moving at the same speed, so the answer is A.
A 3.7-kg object is acted on by two forces. One of the forces is 11 N acting toward the
east. What is the other force if the acceleration of the object is 1.0 m/s2 toward the east?
Answer:
7.3 newtons to the west
Explanation:
3.7kg × 11a - 3.7kg × ? = 3.7n
How much power does it take to lift 70.0 N to 5.0 m high in 5.00 s?
Answer:
Power = 70 W
Explanation:
Given that,
Force, F = 70 N
Height, h = 5 m
Time, t = 5 s
We need to find the power of the object. We know that,
Power = work done/time
Put all the values,
[tex]P=\dfrac{Fd}{t}\\\\P=\dfrac{70\times 5}{5}\\\\P=70\ W[/tex]
So, the required power is 70 W.
how is the process that generates energy in the suns core different from an explosion caused by a chemical reaction
Answer:
[tex]$E = m{c^2}$[/tex]
Explanation:
• The explosion caused by chemical reaction involves conversion of chemical energy into heat and sound, but the total mass of atoms participating in the reaction remains constant.
• In the nuclear fusion reaction, the one happening in the core of the sun, mass is directly converted into energy by the equation [tex]E=mc^{2}[/tex]
Hence, mass remains constant, it just converts in to velocity.
Learn more about nuclear fusion here:
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A hockey puck is sliding across the ice with an initial velocity of 25 m/s. If the coefficient of friction between the hockey puck and the ice is 0.08, how much time (in seconds) will it take before the hockey puck slides to a stop
Answer: 31.89seconds
Explanation:
Based on the information given, we are meant to calculate deceleration which will be:
t = V/a
where, a = mg
Therefore, t = V/mg
t = 25/0.08 × 9.8
t = 25/0.784
t = 31.89seconds
Therefore, the time that it will take before the hockey puck slides to a stop is 31.89seconds.
A Michelson interferometer operating at a 400 nm wavelength has a 3.70-cm-long glass cell in one arm. To begin, the air is pumped out of the cell and mirror M2 is adjusted to produce a bright spot at the center of the interference pattern. Then a valve is opened and air is slowly admitted into the cell. The index of refraction of air at 1.00 atm pressure is 1.00028.
How many bright-dark-bright fringe shifts are observed as the cell fills with air?
Answer:
[tex]m=42\ fringes[/tex]
Explanation:
From the question we are told that:
Wavelength [tex]\lambda=400nm[/tex]
Length of cell arm [tex]h=3.70cm[/tex]
Refraction of air at at 1.00 atm pressure [tex]n=1.00028.[/tex]
Generally the equation for Number of shifts is mathematically given by
[tex]m=N-N_o[/tex]
Since
[tex]N_0=\frac{2t}{\lambda_0}[/tex]
Therefore
[tex]m=\frac{2t}{\lambda_0/n}-\frac{2t}{\lambda_0}[/tex]
[tex]m=\frac{2t}{\lambda_0} n-1[/tex]
[tex]m=\frac{2(3.7*10^{-2})}{400*10^{-9}}*(1.00028-1)[/tex]
[tex]m=51.8[/tex]
[tex]m=42\ fringes[/tex]
resolve the vector shown below into its components
Answer:
ans: option A
Explanation:
components along x- axis is -3x and along x- axes is -2y
now use triangle law of vector addition
In higher mass stars, repeating cycles of fusion will create heavier elements in layers
until which element is created at the center of the core?
hydrogen
iron
uranium
helium
You throw a stone straight down from the top of a tall tower. It leaves your hand moving at 8.00 m/s, Air resistance can be neglected. Take the positive -direction to be upward, and choose y 0 to be the point where the stone leaves your hand. Find the stone's position 1.50s after it leaves your hand.
Express your answer with the appropriate units.
Find the y-component of the stone's velocity 1.50 s after it leaves your hand. Express your answer with t0he appropriate units.
Answer:
The velocity after 1.5 s is 22.7 m/s downwards.
Explanation:
Initial velocity = - 8 m/s
acceleration, a = - 9.8 m/s2
time, t = 1.5 s
Use first equation of motion
v = u + at
v = - 8 - 9.8 x 1.5
v = - 8 - 14.7
v = - 22.7 m/s
Thus, the velocity after 1.5 s is 22.7 m/s downwards.
An alpha particle consists of two protons and two neutrons. How will the emission of an alpha particle affect the following:
a. The atomic number of the atom: _______Atomic Number will go down_______
b. The mass number of the atom: ___Mass number will go down____________
Answer:
a) The atomic number decreases by 2 units
b) the atomic mass decreases by 4 units
Explanation:
An alpha particle is a helium nucleus, which is why it is made up of two positive protons and two negative neutrons, the mass of the particles is almost the same.
a) The atomic number decreases by 2 units
b) the atomic mass decreases by 4 units
The v-t graph of a moving body is given below. The distance covered by the body in
the first 40s is _________and its acceleration during the last 40s is _____________.
a) 3200m; 2ms-1
b) 700m; -2ms-2
c) 900m; - 2ms-2
d) 900m; 2ms-2
Answer: The correct answer is a) 3200 m, [tex]-2m/s^2[/tex]
Explanation:
Speed is defined as the ratio of distance travelled to the time taken. The equation follows:
[tex]\text{Speed}=\frac{\text{Distance travalled}}{\text{Time taken}}[/tex]
From the graph:
Speed for the first 40 s, v = 80 m/s
Time taken, t = 40 s
Putting values in above equation, we get:
[tex]\text{Distance travalled}=(80 m/s\times 40s)=3200 m[/tex]
Acceleration is defined as the ratio of change of velocity to the change of time. The equation follows:
[tex]\text{Acceleration}=\frac{\Delta v}{\Delta t}=\frac{v_2-v_1}{t_2-t_1}[/tex]
From the graph, for the last 40 sec:
Initial velocity, [tex]v_1[/tex] = 80 m/s
Final velocity, [tex]v_2[/tex] = 0 m/s
Initial time, [tex]t_1[/tex] = 40 s
Final time, [tex]t_2[/tex] = 80 s
Putting values in above equation, we get:
[tex]\text{Acceleration}=\frac{(0-80)m/s}{(80-40)s}\\\\\text{Acceleration}=\frac{-80m/s}{40s}=-2m/s^2[/tex]
Hence, the correct answer is a) 3200 m, [tex]-2m/s^2[/tex]
A ball player catches a ball 3.55 s s after throwing it vertically upward. with what speed did he throw it
Answer:
i believe he threw the ball up at about 18 mph
Explanation:
Can somebody please help
Answer:
Explanation:
part A: C
part B: B
The power in an electrical circuit is given by the equation P= RR, where /is the current flowing through the circuit and Ris the resistance of the circuit. What is the current in a circuit that has a resistance of 100 ohms and a power of 15 watts?
[pleas ee helpppp)
I= 0.39 A
OPTION B is the correct answer.
A cheetah is running in a straight line in pursuit of prey. The cheetah's mass is 63.9 kg. Through its running motion, assume the cheetah experiences a constant forward force of 609.1 N. Also, assume the cheetah experiences a constant 107.9 N air resistance force that is opposite its motion. What is the magnitude of the cheetah's acceleration, in units of m/s2?
Answer:
a = 7.84 m / s²
Explanation:
For this exercise let's use Newton's second law
F - fr = m a
indicate that the force is F = 609.1 N and the friction force is fr = 107.9 N and is constant
a = [tex]\frac{F - fr}{m}[/tex]
let's calculate
a = [tex]\frac{ 609.1 - 107.9 }{63.9}[/tex]
a = 7.84 m / s²
what is the main function of a step-up and step-down transformers
Answer:
Explanation:
The difference between step-up and step-down transformer is given below:-
Step-up transformer
i) It increases the voltage.
ii) It decreases the current strength.
iii) It has a greater number of turns in secondary as compared to the primary.
iv) The wire of primary is thicker than that of the secondary coil.
Step-down transformer
i) It decreases the voltage.
ii) It increases the current strength of the secondary.
iii) It has less number of turns in secondary as compared to the primary.
iv) The wire of the secondary coil is thicker than that of the primary coil.
factors that favour mining in South Africa
Answer:
According to the data, factors influencing mining investment in South Africa's favour are the availability of labour and skills, the quality of the country's infrastructure, the quality of its geological database, and the State's environmental regulations.
Two identical loudspeakers 2.30 m apart are emitting sound waves into a room where the speed of sound is 340 m/s. Abby is standing 5.00 m in front of one of the speakers, perpendicular to the line joining the speakers, and hears a maximum in the intensity of the sound. Part A What is the lowest possible frequency of sound for which this is possible
Answer:
By the Pythagorean Theorem the distances from the speakers os
5 and 5.5 (rounding) meters - let y be the wavelength in the solution
n y = 5 n is number of wavelengths from speaker
(n + m) y = 5.5 m must be integral for constructive interference
m y = .5 subtracting equations
m = 2 and y = ,25 for the above conditions
(n + 2) y = 5.5 substituting for m
n = 5.5 / .25 - 2 = 20
f = v / y using frequency of sound
f = 340 / .25 = 1360 / sec for lowest frequency
Check: D1 = y n = ,25 * 20 = 5
and D2 = .25 * 22 = 5.5 for the distances traveled
Suppose 4 J of work are needed to stretch a spring 14 cm from its natural position. How much work is needed to stretch it 20 cm from its natural position
Answer:
8.16 J
Explanation:
Applying,
W = ke²/2................. Equation 1
Where W = work done in stretching the spring, k = spring constant, e = extension
make k the subject of the equation
k = 2W/e²................ Equation 2
From the question,
Given: W = 4 J, e = 14 cm = 0.14 m
Substitute these values into equation 2
k = 2(4)/0.14²
k = 8/0.0196
k = 408.16 N/m
If stretchd 20 cm from its natural length,
Therefore,
e = 20 cm = 0.2 m
W = 408.16(0.2²)/2
W = 8.16 J
The triceps muscle in the back of the upper arm extends the forearm. This muscle in a professional boxer exerts a force of 2.00\times 10^32.00×10 ^3 N with an effective perpendicular lever arm of 3.00 cm, producing an angular acceleration of the forearm of 120 rad/s^2 .
What is the moment of inertia of the boxer's forearm?
Answer:
Explanation:
From the given information:
The torque produced due to the force can be expressed as:
[tex]\tau = F \times r[/tex]
where;
[tex]\tau[/tex] = torque
F = force exerted
r = lever's arm radius
[tex]\tau[/tex] = [tex]2.00 \times 10^3 \times 0.03 m[/tex]
[tex]\tau[/tex] = 60 N.m
However, equating the torque with the moment of inertia & angular acceleration, we use the equation:
[tex]\tau[/tex] = I∝
60 Nm = I × 120 rad/s²
I = 60 Nm/120 rad/s²
I = 0.5 kg.m²