Which of the following best describes a completely elastic collision?

The kinetic energy (K) of the system before the collision equals K after.

The potential energy (U) of the system before the collision equals U after.

The kinetic energy (K) of the system before the collision is greater than K after.

The kinetic energy (K) of the system before the collision is less than K after.,

An atom with a negative four charge will have 4 more electrons than protons.

An atom that has a negative four charge will have 4 more electrons than protons. This is because the charge of an atom is determined by the difference between the number of protons and electrons. A neutral atom has an equal number of protons and electrons, leading to no net charge. If there are more electrons than protons, the excess negative charges from the electrons result in a negative charge for the atom.

In the case of an atom with a negative four charge, also known as an anion, the atomic charge can be calculated as number of protons - number of electrons. Since each electron has a negative charge equal to the positive charge of a proton, the atom in question with a -4 charge must have four more electrons than protons.

Answer:

nuclear fission and gravitational contraction

Explanation:

Which two energy sources can help a star maintain its internal thermal pressure? which two energy sources can help a star maintain its internal thermal pressure? nuclear fission and gravitational contraction nuclear fusion and chemical reactions chemical reactions and gravitational contraction nuclear fusion and gravitational contraction nuclear fusion and nuclear fission?

What is Nuclear fission is when a heavy nucleus split to release energy . it splits into two lesser nuclei.

Gravitational contraction:

is when there is collapse of an object in space due to the influence of its own gravity. This two phenomenon makes it possible for a satr to maintain its thermal (heat )pressure.

Final answer:

Feeling the heat from a heater at a distance is an example of heat transfer by radiation, where electromagnetic waves emitted by the heater are absorbed by the skin, causing a warming sensation.

Explanation:

Feeling the heat waves from a small electric heater on your hands and face, even though the heater is on the other side of the room, is an example of heat transfer by radiation. This occurs when a hot body like a heater emits electromagnetic waves that travel through the space and are absorbed by your skin, warming you without the need for a medium. This type of heat transfer is the same that occurs when we feel the warmth from the Sun or when an oven warms us as we walk by.

The effective spring constant of the bathroom scale is approximately 174,738 N/m.

The mass of the player is approximately 69.51 kg.

To determine the spring constant of the bathroom scale, you can use Hooke's law, which relates the force applied to a spring (F) to its displacement (x) and the spring constant (k):

F = -k * x

In this case, we know that the scale depresses 0.65 cm (which is equivalent to 0.0065 meters) under a load of 115 kg. We can use this information to find the spring constant (k):

115 kg * 9.81 m/s² = k * 0.0065 m

Now, solve for k:

k = (115 kg * 9.81 m/s²) / 0.0065 m

k ≈ 174,738 N/m

Hence, the effective spring constant of the bathroom scale is approximately 174,738 N/m.

Now, to find the mass of the player who depresses the scale by 0.39 cm (which is equivalent to 0.0039 meters), you can use Hooke's law again:

F = -k * x

Where:

F is the force exerted by the player's weight (in Newtons)

k is the spring constant (we just found it to be 174,738 N/m)

x is the displacement of the spring (0.0039 meters)

Now, solve for F:

F = -174,738 N/m * 0.0039 m

F ≈ -681.882 N

Since weight is the force due to gravity (F = m * g), where "m" is the mass of the player and "g" is the acceleration due to gravity (approximately 9.81 m/s²), we can find the mass of the player:

m = F / g

m = (-681.882 N) / (9.81 m/s²)

m ≈ -69.51 kg

The negative sign indicates that the player's weight is acting in the opposite direction of the scale's displacement.

Hence, the mass of the player is approximately 69.51 kg.

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Answer: The correct option is C.

Explanation:

The sound wave is reflected back after striking from the barrier. This is called the reflection of the sound.

When the sound wave incidents on the barrier then it is called incident wave.

When the sound wave gets reflected back from the barrier then it is called reflected wave.

Ultrasound imaging is a medical technique which is used to take the image of the internal parts of organ of the body.

Echolocation is the process which is used by several species. It is used by bats to locate its prey. It is the biological SONAR.

Therefore, echolocation and ultrasound imaging are same as they both use the reflection of sound waves.

The buoyant force on an object fully submerged in a liquid depends on the object's volume.and the density of the liquid.  

Buoyant force also known as upthrust, is an upward force exerted by a fluid that resists the weight of a partly or completely submerged object.

The weight of the overlying fluid causes pressure to rise with depth in a column of fluid.

The buoyant force on an object fully submerged in a liquid depends on the object's volume.and the density of the liquid.  

Hence option 1 and 3 is correct .

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Answer: Potential Energy = 7,000 Joules(A)

Explanation:

Potential Energy is the energy possessed by the virtue of its position and it is given as,

P. E = mgh

Where m is the mass= 70kg

g is acceleration due to gravity =10m/s²

h= height = 10m

P. E = 70×10×10

P. E= 7000J

Therefore the potential energy is 7000J

Infrared light, microwave radiation, and radio waves are all forms of light that have lower energy and frequency than what our eyes can perceive. These forms of light are part of the electromagnetic spectrum and have various applications in technology.

The forms of light that are lower in energy and frequency than the light that our human eyes can see are infrared light, microwave radiation, and radio waves. These forms of light make up part of the electromagnetic spectrum, which ranges from high-frequency, high-energy gamma rays to low-frequency, low-energy radio waves.

In relation to the visible light we see, these energies are less, and therefore their frequencies are also lower. To illustrate, infrared light is just below red light on the spectrum and is often associated with heat radiation. Microwave radiation is commonly used in technologies such as microwave ovens and wireless communication devices, and radio waves are the longest and hence the lowest energy/frequency waves in the spectrum, utilized in broadcasting signals such as television and radio.

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Power in physics is the rate at which energy is transferred, correctly measured in joules per second or watts. Option 2

Power in physics is defined as the rate at which work is done or the rate at which energy is transferred. This rate is typically measured in joules per second (J/s), which is also known as a watt (W). To clarify the options provided in the question, power cannot be correctly expressed in joules per watt or newtons per second as these do not represent the rate of energy transfer.

Instead, power is correctly expressed in joules per second, which is equivalent to watts. For instance, a device like a light bulb that uses electrical energy to produce light and heat will have its power consumption rated in watts. The higher the wattage, the more power it consumes over a given period of time.

Additionally, power is sometimes measured in units such as the horsepower (hp), where 1 hp equals 746 watts. Furthermore, it is important to realize that terms like kilowatt-hour (kWh) are units of energy, not power. For instance, a 2000-watt iron would use 2 kWh of energy over one hour, which is equal to 2 x 3.6 million joules. Option 2

The work done on the particle as it moves from x = 0 to x = 1 meter under the force F(x) = exp(-x/2 + 6) is obtained by integrating the force function over the distance, resulting in a measurable amount of work in Joules.

The work done W on a particle as it moves from initial position xi to final position xf under a force F(x) is calculated by integrating the force over the distance. Considering the given force function F(x) = exp(-x/2 + 6), the work done from x = 0 to x = 1 meter is:

W = ∫ F(x) dx

= ∫ exp(-x/2 + 6) dx from x = 0 to x = 1

= ∫ e(-x/2 + 6) dx from x = 0 to x = 1

= -2e(-x/2 + 6) | from x = 0 to x = 1

= -2(e(-1/2 + 6) - e6)

= -2(e(11/2) - e6) Joules

By calculating the definite integral, we can find the total amount of work done in Joules on the particle during this displacement.

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The 1.3 kW hair dryer consumes less energy than the 10 W night light. Calculations show that the hair dryer uses 0.2167 kWh, while the night light uses 0.24 kWh.

The 1.3 kW hair dryer used for 10 minutes consumes more energy compared to the 10 W night light left on for 24 hours. To calculate energy consumption, we use the formula: Energy = Power x Time. For the hair dryer: Energy = 1.3 kW x (10 min / 60 min) = 0.2167 kWh. For the night light: Energy = 10 W x 24 hours = 0.24 kWh. Therefore, the hair dryer consumes less energy.

Answer: Vas deference

Explanation: This is a method of contraception in uses a small surgical procedure. This method is a permanent method of contraception.

During this procedure, male vas deference are cut and tied together or we can say it is sealed to prevent the path of sperm from getting into the urethra and in this way it prevents fertilization of a females egg during the sexual intercourse.

Answer: D. 10 degree angle

All places on Earth received sunlight but in different angles. The smallest area, which is the north of the Arctic Circle receive sunlight at a 10 degree angle because of the tilted axis of rotation. Usually, the sun’s rays are the most intense at the equator and the least intense at the poles as Earth revolves around the sun.

Answer:

The angle that will fall over the smallest area is 10

Explanation:

This atomic model was developed in 1904 by the British scientist J.J. Thomson, from his discovery of the existence of the electron in 1897.

Taking into consideration that at that time there was still no evidence of the atom nucleus, Thomson thought the electrons (with negative charge) were immersed in a substance (the atom) of positive charge that counteracted the negative charge of the electrons. Just like the raisins embedded in a pudding or bread.

That is why this model was called the raisin pudding atomic model

When a fly collides with a moving car's windshield, the force exerted by both on each other is equal in magnitude due to Newton's Third Law of Motion. The differing outcomes (the fly typically being destroyed while the car remains largely unaffected) are a result of the vastly different masses and resulting accelerations, not a difference in the magnitude of force.

When a fly hits the windshield of a rapidly moving car, an interesting physics principle comes into play, known as Newton's Third Law of Motion. This law states that for every action, there is an equal and opposite reaction. Therefore, the force that the fly exerts on the windshield is equal in magnitude to the force that the windshield exerts on the fly during the collision. However, the outcomes are vastly different for the fly and the car due to their significant difference in mass. The car has a much larger mass and therefore experiences a negligible acceleration from the force, while the light-mass fly undergoes a large acceleration, often resulting in its death.

The Third Law of Motion can be counterintuitive because we observe the effects of the forces differently due to the difference in mass and resulting acceleration. But it’s crucial to understand that in terms of the forces experienced by both objects, they are identical. This is why the correct answer is that neither the car nor the fly experiences a greater force than the other in magnitude during the collision.

Final answer:

Using Ohm's Law, which states I = V / R, the current of a circuit with a 3.0-volt battery and 1.0 ohm of resistance is calculated to be 3.0 amperes.

Explanation:

Calculating Current with Ohm's Law

Ohm's Law describes the relationship between current (I), voltage (V), and resistance (R) in an electrical circuit, stating that I = V / R. To calculate the current in a circuit with a 3.0-volt battery and 1.0 ohm of resistance, you would use the formula I = V / R. Plugging the values into the formula gives us I = 3.0 V / 1.0 Ω, which simplifies to I = 3.0 A. Therefore, the current of the circuit would be 3.0 amperes.