A body is placed on a rough inclined plane. Why does the frictional force decrease with the increase of angle of inclination

PWC operators can minimize annoying noise using destructive interference, where a second sound with maxima and minima exactly opposite the incoming noise is introduced. This resulting sound is much quieter. This technique can also apply engineering changes to parts that could resonate at the annoying sound frequency.

PWC operators can minimize annoying noise using a method based on sound interference, notably destructive interference. Figure 17.23 provides a demonstration with headphones that use this principle to cancel noise. The main idea of noise cancellation is to introduce a second sound with its peaks and troughs exactly opposite from the incoming noise. This is achieved through a fast electronic analysis. The two sounds then interfere destructively, resulting in a much quieter sound.

Achieving completely destructive interference in practice is rarely possible, but using this method, it's feasible to reduce noise levels by 30 dB or more. Notably, the principle of Pascal's principle is at play, where pressures from two different sources add and subtract like simple numbers. This results in a lower-intensity sound, i.e., less noise.

This technique can be extended to include studying parts that could resonate at the frequency of the annoying sound, and then engineering changes to eliminate that resonance. It may involve changing the material used or changing the length of the part, as discovered in Fourier Analysis.

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In vehicles with airbags, maintain 12-15 inches of clearance from the steering wheel. Avoid collisions by driving safely: obeying laws, keeping distance, and using defensive driving strategies.

In a vehicle equipped with an airbag, it is crucial to ensure that there is a sufficient clearance of 12-15 inches between your chest and the center of the steering wheel. This safety precaution is just one of several essential tips to protect yourself while driving. Collisions on the road are frequently the result of negligent driving behaviors, including speeding, disregarding traffic signals and stop signs, and driving under the influence of alcohol or drugs. To minimize the risk of being involved in a collision, there are several fundamental steps you should follow.

Maintaining an appropriate following distance behind the vehicle in front of you is paramount. This allows you ample time to react to sudden stops or emergencies, reducing the likelihood of a rear-end collision. Choosing the correct lane is another critical aspect of safe driving. Stay in the right lane if you are moving slower than the flow of traffic and use the left lane for passing. Driving defensively means constantly being aware of your surroundings, anticipating the actions of other drivers, and being prepared to react swiftly and safely.

In summary, for your safety on the road, ensure proper clearance from the steering wheel in airbag-equipped vehicles and adhere to safe driving practices. Collisions often result from avoidable mistakes, so by obeying traffic laws, maintaining a safe following distance, choosing the appropriate lane, and adopting a defensive driving mindset, you can significantly reduce the risk of accidents and protect yourself and others on the road.

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The correct formula for this simple harmonic motion is:

x = (6.0) cos [ (3 pi) t + pi/3 ] 

A. Calculating for displacement x at t = 2:

x =6.0 cos (19/3 pi)
x = 6 (0.5)

x = 3 m

B. Velocity is equivalent to the 1st derivative of the equation. v = dx / dt

 Velocity v = dx/dt = -18 pi sin (3pi t + pi/3) 

v = - 18 pi sin (6pi + pi/3)

v = 49.0 m/s

C. Acceleration is the 2nd derivative or the 1st derivative of velocity dv / dt
Acceleration a = dv/dt = -54 pi^2 cos(3pi t + pi/3) 

a = -54 pi^2 cos(3pi * 2 + pi/3)

a = 386.34 m/s^2

D. Phase = pi/3 

E. frequency f= 3pi/2pi = 1.5Hz 

F. period = 1/f = 1/1.5 = .6667sec 

Final answer:

The position function x(t) = X cos(ωt + φ) represents the simple harmonic motion of a body. At t = 2.0 s, we can calculate the displacement, velocity, acceleration, and phase of the motion. The frequency and period of the motion can also be determined.

Explanation:

In simple harmonic motion, the displacement of a body at any given time t is given by the equation x(t) = X cos(ωt + φ), where X is the amplitude, ω is the angular frequency, and φ is the phase angle.

(a) At t = 2.0 s, plugging in the values, we have x(2.0) = 6.0 cos((3π rad/s) * 2.0 s + π/3 rad).

(b) Velocity can be obtained by taking the derivative of the displacement function, v(t) = -ωX sin(ωt + φ).

(c) Acceleration can be obtained by taking the derivative of the velocity function, a(t) = -ω²X cos(ωt + φ).

(d) The phase of the motion refers to the initial position of the body and is represented by the phase angle φ.

(e) The frequency of the motion is given by f = ω/(2π) = (3π rad/s)/(2π) = 3/2 Hz.

(f) The period of the motion is the reciprocal of the frequency, T = 1/f = (2/3) s.

Final answer:

To convert a thermos into an open energy system, allow for energy exchange by adding openings or using less insulating materials, thus modifying the thermos to gain or lose energy like other open systems.

Explanation:

To change a thermos into an open energy system, you must allow for the transfer of energy between the thermos and its surroundings. A thermos is designed to be an isolated system, minimizing energy exchange with the environment to keep its contents at a consistent temperature. However, to convert it into an open system, modifications can be implemented such as adding openings or using materials that facilitate heat exchange. It is through such alterations that the thermos can then gain or lose energy, behaving similarly to a pot of water on a stove, which is considered an open system because it loses heat to the air.

While a thermos typically serves to approximate an isolated system, where the coffee inside remains hot by limiting heat transfer, to convert it to an open system, one might drill holes in it or construct it from a less insulating material. Once converted, the thermos could then absorb energy from the environment or release energy to it, such as solar radiation warming the contents or ambient air cooling them down. This adherence to thermodynamics principles demonstrates how the laws of thermodynamics govern the energy dynamics of open systems. Ultimately, converting a thermos to an open system reflects the first law of thermodynamics, where the energy within the system changes through the work done on it or by it.

The correct matches are:

1. obsidian - B) extrusive igneous;

2. granite - A) intrusive igneous;

3. conglomerate - C) clastic sedimentary;

4. evaporite - E) chemical sedimentary;

5. coal - D) organic sedimentary;

6. marble - F) metamorphic;

There are three big groups of rocks, igneous, sedimentary, and metamorphic. They further diversify into multiple types of rocks in accordance to their structure, chemical composition, crystallization, formation etc. The igneous can simple be divided into intrusive (ones that formed on the surface or very close to it) and extrusive (ones that formed deep into the ground). The sedimentary rocks can be divided into multiple groups in accordance to their composition, as some can be made of multiple sediments, some from organic material, some from mixture of sediments and organic material etc. And the metamorphic can simply be seen as rocks that come to be as a result of the transformation of the other two types if they are under big pressure and temperatures for longer periods of time.

The answer is CFC – 22 or HCFC - 22. To locate leaks, it is easily accomplished using a pressure – regulated dry nitrogen charge with CFC – 22. But some technicians prefer to use Refrigerant – 22 (HCFC – 22) to pressurize the system without the use of nitrogen. CFC – 22 is also known as Chlorodifluoromethane. This is a hydrochlorofluorocarbon (HCFC). This is better recognized as HCFC-22, or R-22. It is usually used as a propellant and refrigerant. While HCFC – 22 is also known as class II hydrochlorofluorocarbon refrigerant that is less harmful to the ozone than R -12. If HCFC – 22 is used for leak testing, all refrigerant must be first detached from the system. After the leak test, HCFC – 22 should be remove before putting any other refrigerant. Do not mix refrigerants. Both HCFC – 22 and R -134a fall into the kind of refrigerants known as combustible. If exposed to oxygen, they will burn when under pressure or exposed to high temperatures. 

For an object starting from rest and accelerating with a constant acceleration, the distance travelled is proportional to the square of the time. So, if an object travels 2.0 furlongs in the first 2.0 seconds, it will travel 8.0 furlongs in the first 4.0 seconds.

In the problem, we have an object accelerating from rest and we know that distance covered is proportional to the square of the time. In the first 2.0s, the object has covered a distance of 2.0 furlongs. Hence, if we double the time from 2.0s to 4.0s, since distance covered is proportional to the square of time, the object will cover 2*(2.0s)^2 = 8.0 furlongs in the first 4.0s. This relationship is based on the physics principle of displacement which defines that in constant acceleration, distance travelled is proportional to square of time.

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Option A: The skier has potential and kinetic energy

A turtle crawls and covers a distance of 4.77 m in a time of 19.5 seconds, then the velocity of the turtle will be equal to 0.245 m/s.

Velocity is the rate of change of a traveling object's direction, as measured by a certain unit of time and as seen from a specific vantage point. Speed is a basic concept in kinematic, the branch of special relativity that studies how bodies move.

A scientific vector quantity called velocity must have both a magnitude and direction to be described.

As per the given data provided by the question,

The distance traveled by the turtle, d = 4.77 m

Time is taken by the turtle, t = 19.5 seconds.

[tex]Velocity(v) = Distance(d)/Time(t)[/tex]

v = 4.77/19.5

v = 0.245 m/s.

Therefore, the velocity of the turtle is 0.245 m/s.

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The best answer for this question would be:

 The onset of World War II 

It started during World War II because during the war, soldiers needed to upgrade their uniform. This is to enable them to adapt to the battlefield where the deconstruction happened and courses of history have changed.

Nitrates and phosphates is correct on gradpoint

A chemical property of iron is its tendency to react with oxygen to form iron oxide, otherwise known as rust, which is a process called corrosion.

A chemical property of iron is its tendency to react with oxygen, which is an example of corrosion. This reaction forms iron oxide, commonly known as rust. Unlike physical properties like melting point, hardness, and strength under compression, chemical properties describe the potential for a substance to change its chemical structure. Corrosion is one such property that can only be observed as the substance is transformed into a different substance, in this case, iron becoming iron oxide.

Answer:

Increase of temp causes the rate of a reaction to increase, which increases the kinetic energy of molecules, causing more collisions

To find initial velocity in projectile motion without the angle, use the vertical motion information to calculate time of flight, then use horizontal distance and time to find horizontal velocity, and combine it with initial vertical velocity using the Pythagorean theorem.

To find the initial velocity in projectile motion without knowing the angle, one approach is to use the given vertical motion information. According to the provided discussion, if a projectile has an initial vertical velocity (Vy0) of 14.3 m/s and lands 20.0 m below its starting altitude, the time of flight is 3.96 seconds. This time is solely determined by the vertical motion, as the vertical acceleration is constant due to gravity.

Once the time of flight is known, you can calculate the horizontal component of the velocity (Vx) as follows: Vx = horizontal distance traveled / time of flight. It is important to note that Vx is constant throughout the motion if air resistance is negligible. The horizontal component can then be used in combination with the vertical component to calculate the total initial velocity (Vo). This can be done by using the Pythagorean theorem, Vo = √(Vx² + Vy0²).