Answer:
Answer: B. $0.78.
Explanation:
Cost of Electricity
The rate of the cost of electricity is usually expressed in $/kWh or cents/kWh because the consumption of electricity is measured in Kilowatts-hour.
The local power company charges 5.79 cents/kWh.
We are required to calculate the cost to run a 120 W stereo system for 4 hours per day for 4 weeks.
The total consumption time is 4 hours/day * 7 days/week *4 weeks = 112 hours
The total energy consumed is 120 W * 112 h =13,440 Wh.
Converting to kWh: 13,440 Wh/1,000 = 13.440 kWh.
Finally, we multiply by the cost rate: 5.79 cents/kWh * 13.440 kWh = 77.8 cents/100 = $0.78.
Answer: B. $0.78.
Does an object with constant speed also have constant velocity?. Single choice.
Answer: No, constant speed does not mean constant velocity.
A classic often used example would be to consider a car driving in circles. If the speedometer reads say 20 mph the entire time, then the speed of the car is held constant (ie the same). But the velocity is changing because velocity measures direction along with speed. The car is changing direction as it moves in a circle.
Gradually increasing resistance, increasing repetition, increasing sets are examples of which principle?
Answer:
Resistance training.
Explanation:
Resistance training is based on the principle of gradually increasing resistance, increasing repetition and increasing sets to acquire resistance. Resistance training refers to those physical exercises which are designed and done to improve strength and endurance of the body. Resistance training uses the principle of repetition of a particular exercise in order to attain strength as well as resistance against diseases.
A 15 kg box is sliding down an incline of 35 degrees. The incline has a coefficient of friction of 0.25. If the box starts at rest, how fast is it moving after it travels 3 meters?
The box has 3 forces acting on it:
• its own weight (magnitude w, pointing downward)
• the normal force of the incline on the box (mag. n, pointing upward perpendicular to the incline)
• friction (mag. f, opposing the box's slide down the incline and parallel to the incline)
Decompose each force into components acting parallel or perpendicular to the incline. (Consult the attached free body diagram.) The normal and friction forces are ready to be used, so that just leaves the weight. If we take the direction in which the box is sliding to be the positive parallel direction, then by Newton's second law, we have
• net parallel force:
∑ F = -f + w sin(35°) = m a
• net perpendicular force:
∑ F = n - w cos(35°) = 0
Solve the net perpendicular force equation for the normal force:
n = w cos(35°)
n = (15 kg) (9.8 m/s²) cos(35°)
n ≈ 120 N
Solve for the mag. of friction:
f = µ n
f = 0.25 (120 N)
f ≈ 30 N
Solve the net parallel force equation for the acceleration:
-30 N + (15 kg) (9.8 m/s²) sin(35°) = (15 kg) a
a ≈ (54.3157 N) / (15 kg)
a ≈ 3.6 m/s²
Now solve for the block's speed v given that it starts at rest, with v₀ = 0, and slides down the incline a distance of ∆x = 3 m:
v² - v₀² = 2 a ∆x
v² = 2 (3.6 m/s²) (3 m)
v = √(21.7263 m²/s²)
v ≈ 4.7 m/s
NEED AWNSER NOW! WILL MARK BRAINLY! Which term is defined as the ratio of the speed of light in a vacuum to the speed of light in the material it is passing through?
index of reflection
index of refraction
angle of reflection
angle of incidence
Answer:
Index of refraction.
Answer:
index of refraction
Explanation:
I just took the k12 quiz.
A ball of mass 0.0887 kg is dropped from a height 1.76 m above the ground. The acceleration of gravity is 9.8 m/s 2 . Neglecting air resistance, determine the
Answer:
determine the.........
True or False? The horizontal component of velocity of a projectile remains constant; the vertical component of velocity changes throughout the trajectory.
Answer:
False!!
Explanation:
A billiard ball moving at 5 m/s strikes another ball which is initially at rest. After the collision, the first ball moves at a velocity of 4.35 m/s at an angle of 30o below its original motion. Find the velocity and angle of the second ball after the collision. Assume that the collision is perfectly elastic.
Answer:
The velocity of the second ball is approximately 2.588 m/s
The angle direction of the second ball is 75° counterclockwise from the horizontal
Explanation:
The initial velocity of the first billiard ball = 5 m/s
The initial velocity of the billiard ball the first billiard ball strikes = 0 m/s
The final velocity of the first billiard ball = 4.35 m/s
The final direction of motion of the first billiard ball = 30° below its original motion
For perfectly elastic collision, whereby the target is at rest initially, by conservation of momentum, we have;
m₁ × [tex]\underset{v_1}{\rightarrow}[/tex] = m₁·[tex]\underset{v'_1}{\rightarrow}[/tex] + m₂·[tex]\underset{v'_2}{\rightarrow}[/tex]
Which gives;
m₁ × 5·i = m₁·((√3)/2×5·i - 2.5·j) + m₂·[tex]\underset{v'_2}{\rightarrow}[/tex]
∴ m₂·[tex]\underset{v'_2}{\rightarrow}[/tex] = m₁ × 5·i - m₁·((√3)/2×5·i - 2.5·j)
m₂·[tex]\underset{v'_2}{\rightarrow}[/tex] = m₁ × 5·(1 - √3/2)·i + m₁·2.5·j = m₁ × 2.5·(2 - √3)·i + m₁·2.5·j
Therefore, given that the mass of both billiard balls are equal, we have, m₁ = m₂, which gives;
m₂·[tex]\underset{v'_2}{\rightarrow}[/tex] = m₁·[tex]\underset{v'_2}{\rightarrow}[/tex] = m₁ × 2.5·(2 - √3)·i + m₁·2.5·j
∴ [tex]\underset{v'_2}{\rightarrow}[/tex] = 2.5·(2 - √3)·i + 2.5·j
The magnitude of the velocity of the second ball is [tex]\underset{v'_2}{\rightarrow}[/tex] = √((2.5·(2 - √3))² + 2.5²) ≈ 2.588 m/s
The direction of the second ball, θ = arctan(2.5/((2.5·(2 - √3))) = 75° counterclockwise from the horizontal.
Why do these two magnets attract each other?
A. The poles that face each other are opposite magnetic poles.
B. The poles of one magnet cause the other magnet to have a
magnetic field.
C. The magnetic fields leave the magnets and concentrate between
them.
D. The magnetic field is weaker between the two magnets.
Answer:
A
Explanation:
When two magnets are brought near each other, like poles repel; opposite poles attract. We like to represent this force effect of a magnet on iron-like objects with a concept called magnetic field. The concept of field can be best understood if we remember the gravitational force of Earth on object near it.
Every magnet has two poles. The same pole repels while opposite poles attract each other. Option (A) is correct. The poles that face each other are opposite magnetic poles.
What is a magnet?A magnet is a substance or item that generates a magnetic field. This magnetic field is invisible, but it is responsible for a magnet's most remarkable property.
A force that attracts or repels other ferromagnetic elements such as iron. Every magnet has two poles. The same pole repels while opposite poles attract each other.
Due to polarity Option (A) is correct. Hence the poles that face each other are opposite magnetic poles.
To learn more about the magnets refer to the link;
https://brainly.com/question/19542022
Question 8 of 15
Which of the following distinguishes electromagnetic waves from mechanical
waves?
A. They carry energy.
B. They have frequencies.
C. They have wavelengths.
D. They don't require a medium to travel through.
Answer:
D. They don't require a medium to travel through.
Explanation:
Electromagnetic waves and mechanical waves are both types of waves. Electromagnetic waves are waves that arise from the combination of electric and magnetic fields while mechanical waves are waves that arise as a result of transfer of energy via matter.
One major difference between these two types of waves is that electromagnetic waves such as light waves, radiowaves etc. do not need a medium to travel i.e. they can travel through a vacuum, while on the other hand, mechanical waves such as sound waves need a medium to travel.
Answer:
They don't require a medium to travel through
Explanation: hope this helps
Gasoline is an example of an accelerant. True False
Answer:
true
Explanation:
Answer:
I believe its true
Explanation:
Gasoline is the most common fire accelerant used but it could also be present at a scene as an ignitable liquid due to gasoline being a common fuel. Although ignitable liquids are the most common fire accelerants it is possible to have other chemicals being used as a fire accelerant.
Which of the technologies could mostly like be found in a wearhouse
Describe what happens to the moving boat when the oars are out of the water and the forward thrust is zero
Answer:
The boat won't be able to move if the oars were out and there was no thruster. If there was a flow of the water then yes there would be a moving boat.
What movement allows us to move our side to side?
Answer:
Ball-and-socket joints
Explanation:
What equation would you use to solve for voltage?
Answer:
It depends upon what you have given in the question but according to Ohm's law,
[tex]\boxed{V\:= I × R}[/tex]
where, V = voltage (v)
I = current (amperes)
R = resistance (Ω)
Other formulas are:
V = P/IV = √P × RHope it helps!<3
I’ll mark u as brainlist if you get this right!
An alkane has molecular weight 86. Write its molecular formula. What will be its physical state?
C6H14
Gaseous state
it's unsaturated hence gaseous
what are the harmful effects of drugs in the body?
Explanation:
causes hallucinations
causes lung cancer eg cigarettes
causes bad breath
damages the nervous system eg cocaine
Explanation:
Drug use can lead to an addiction. Effects of
drugs on the body can slowly destroy vital
systems and functions. Drug dependence can quickly begin to affect your psychological and physical health, and can also affect your work and social life.
hope it helps!
2. If the initial speed of the baseball in question 1 is v. = 0.0 m/s, what will its speed be when it leaves the pitcher's
hand?
Answer:
Object A has 3 times the mass of object B.
Explanation:
Have a nice rest of your day :)
A man speeding at 40m/s decides to outrun the cops and starts to accelerate at a rate of 2.5m/s² for 12 seconds. How far did he travel in this time?
Answer:
The distance traveled by the man during the acceleration is 1186.32 meters
Explanation:
The initial velocity of the man = 40 m/s
The added acceleration rate of the man to outrun = 2.5 m/s²
The time of acceleration = 12 seconds
The relevant kinematic equation of motion is given as follows;
s = u·t + 1/2·a·t²
Where;
u = The initial velocity of the car the man is driving = 40 m/s
t = The time of travel during acceleration of the car the man is driving = 12 seconds
a = The acceleration by the man to outrun the cops = 2.5 m/s²
s = The distance traveled by the man during the acceleration
Substituting, gives;
s = 40 × 12 + 1/2 × 9.81 × 12² = 1186.32
The distance traveled by the man during the acceleration = s = 1186.32 m.
1 Statues can be sculpted from
Answer:
Other materials from which statues can be sculpted include: contemporary media such as scrap metal, plastic, aluminium, concrete or "found" items, although this latter form of junk art is usually limited to abstract rather than representational works.
for an object in free fall, calculate the rate of change of the velocity from the first to the 100th second (metric units).
Answer:
The rate of change of velocity is 9.81 m/[tex]s^2[/tex].
Explanation:
By using the equation of motion, the velocity of any object in free fall at any instant, [tex]v=u+gt[/tex]
Where u (constant) is the initial velocity,
[tex]g=9.81 m/s^2[/tex] is the acceleration due to gravity,
v= velocity at time t.
To get the rate of change of velocity, differentiating the velocity, v, with respect to time, as
[tex]\frac {dv}{dt}=\frac{d}{dt}(u+gt) \\\\=\frac{d}{dt}u +\frac{d}{dt}(gt) \\\\=0+g\\\\=g[/tex]
[tex]\Rightarrow \frac{dv}{dt}=9.81 m/s^2[/tex]
Hence, the rate of change of velocity is 9.81 m/[tex]s^2[/tex].
how many teeth shows signs of decay?
Answer:
what do you mean
Explanation:
Which of the following is most likely to be a conductor?
OA. Aplastic
OB. A molecule containing only nonmetal atoms
OC. A covalently bonded molecule
D. Acompound containing metallic bonds
Answer:
D.
Explanation:
A compound containing metallic bonds
hope it helps!
in addition to genetics, and blank and blank may also cause premature gray hair?
Answer: heretidey and stress
Explanation:
PLZ HELP MEEEEEEE,;-;
Answer:
thxs for the points
Explanation:
because just started
what is one standard kilogramun si system
Answer:
The kilogram (kg) is defined by taking the fixed numerical value of the Planck constant h to be 6.62607015 ×10−34 when expressed in the unit J s, which is equal to kg m2 s−1, where the meter and the second are defined in terms of c and ∆νCs.
A heat lamp produces 32.8 watts of power at a wavelength of 6.5 mm. How many photons are emitted per second
Answer: 1.1x10^21 photons / sec
Explanation:energy per photon
.. E / photon = hc / L = (6.626x10^-34 J x sec) x (3.00x10^8 m/sec) / (6.5x10^-6m)
.. E / photon = 3.06x10^-20 J / photon
then
.. (32.7 watts) x (1 J/sec / 1watt) x (1 photon / 3.06x10^-20J) = 1.1x10^21 photons / sec
The number of photons are emitted per second will be "1.07".
According to the question,
Power,
P = 32.8 watts= 32.8 J/s
Wave length,
λ = 6.5 μm= [tex]6.5\times 10^{-6}[/tex]
As we know,
→ [tex]E = \frac{hc}{\lambda}[/tex]
By substituting the values, we get
[tex]= \frac{32.8}{\frac{(4.42\times 10^{-34})(3\times 10^{-4})}{4.5\times 10^{-6}} }[/tex]
[tex]= \frac{32.8}{3.055e}[/tex]
[tex]= 1.07[/tex]
Thus the above answer is correct.
Learn more about Photons here:
https://brainly.com/question/14758290
A pressure sensor inside of a mixing tank is designed to turn red when the pressure inside the tank exceeds 1.9 kPa. If the sensor is a square, 10 cm on each side, how great a force must be exerted on the sensor in order for it to turn red?
Answer:
19 N
Explanation:
From the question given above, the following data were obtained:
Pressure (P) = 1.9 kPa
Length (L) = 10 cm
Force (F) =?
Next, we shall convert 1.9 KPa to N/m². This can be obtained as follow:
1 KPa = 1000 N/m²
Therefore,
1.9 KPa = 1.9 KPa × 1000 N/m² / 1 KPa
1.9 KPa = 1900 N/m²
Thus, 1.9 KPa is equivalent to 1900 N/m².
Next, we shall convert 10 cm to m. This can be obtained as follow:
100 cm = 1 m
Therefore,
10 cm = 10 cm × 1 m / 100 cm
10 cm = 0.1 m
Thus, 10 cm is equivalent to 0.1 m
Next, we shall determine the area of the square. This can be obtained as follow:
Length (L) = 0.1 m
Area of square (A) =?
A = L²
A = 0.1²
A = 0.01 m²
Thus, the area of the square is 0.01 m².
Finally, we shall determine the force that must be exerted on the sensor in order for it to turn red. This can be obtained as follow:
Pressure (P) = 1900 N/m²
Area (A) = 0.01 m²
Force (F) =?
P = F/A
1900 = F / 0.01
Cross multiply
F = 1900 × 0.01
F = 19 N
Therefore, a force of 19 N must be exerted on the sensor in order for it to turn red.
the speed of water at the tap of lower storey is more than that in the upper storey
Answer:
Pressure of liquid in container is given by, P= height × density × acceleration of gravity.
At the lower storey, the height of the liquid from the open end is great, since height is directly proportional to pressure, the pressure exerted by liquid is maximum hence increase in velocity of flow.
Unlike the upper storey where the height of water is less hence the pressure exerted by the liquid is minimum which decreases the velocity / speed of liquid flow
The speed of water in the upper story will be lower than the lower storey because the kinetic energy of water in the upper storey will be less than that in lower storey.
What is kinetic energy?Kinetic energy of an object is generated by virtue of the motion of the object. Whereas potential energy of the object is formed by virtue of the position of the object.
Kinetic energy depends on the mass of velocity of the object by the equation:
KE = 1/2 Mv²
Potential energy of a body p = Mgh
where, m is mass, g is acceleration due to gravity and h be the height of the object from the surface.
Water at the tap of upper storey is at more height from the surface and thus, having greater potential energy than that in lower storey. Hence, the flow of water will be reduced since it possess more potential energy than kinetic energy.
To find more on potential energy, refer here;
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what is the function of brushes in D.C motor
Answer:
to transfer the voltage
Explanation:
The brushes make physical contact with the commutator. When a DC voltage is applied to the brushes, that voltage is transferred into the commutator which, in turn, powers the windings. This electrical input generates a magnetic field around the armature.