A group of a few thousand stars that are loosely held together by gravity is called a

9x10^13 J is the energy released if a sample loses 0.0001 kg mass through radioactive decay.

As in step with the quantum theory, it isn't always feasible to predict whether a given atom will undergo radioactive decay or nuclear disintegration. Not unusual examples of radioactive decay consist of alpha decay, proton emission, double proton emission, beta decay, electron capture, and neutron emission.

Radioactive decay is the system via which a volatile atomic nucleus loses electricity by radiation. A material containing unstable nuclei is considered radioactive. Three of the most common kinds of decay are alpha decay, beta decay, and gamma decay, all of which contain emitting one or greater debris.

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Momentum is found by multiplying an object's mass by its velocity. While velocity influences momentum, mass plays a significant role, hence a player's momentum is much larger than a football's, despite having less velocity. Comparatively, an elephant could have more momentum than a cheetah, depending on their respective masses and velocities.

Momentum is a crucial concept in physics, and it is calculated as the product of an object's velocity and mass (momentum = mass x velocity). So, the momentum changes when either mass or velocity alters. When comparing the velocity of a ball and a player, even though the ball may have greater velocity, the player, having much more mass, thus has a significantly larger momentum. The player's momentum is about 86 times greater than the football's. As such, the player's motion is only slightly affected when the ball is caught, due to their greater momentum.

In another example, to determine which has a larger magnitude of momentum; a 3000-kg elephant moving at 40 km/h or a 60-kg cheetah moving at 112 km/h, we would need to calculate the momentum for both and compare. An object's mass and velocity both play an integral role in determining its momentum.

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The dark-colored rock pocket mice on dark lava flows have white bellies, as there is no selection for dark bellies by visual predators.

Natural selection is the process of choosing an animal with specific traits for the next generation.

A genetic mutation that alters their hue caused this to happen. This is a consequence of natural selection in turn. Those with advantageous qualities are decided by nature to survive and procreate.

The procedure that improves an organism's chances of surviving is called a mutation. A dark belly can be advantageous for reproduction. White bellies are crucial for camouflaging.

Therefore, due to the lack of selection for dark bellies by visual predators, the dark-colored rock pocket mice on black lava flows have white bellies.

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The law of conservation of momentum tells us that momentum is conserved, therefore total initial momentum should be equal to total final momentum. In this case, we can expressed this mathematically as:

mA vA + mB vB = m v

where, m is the mass in kg, v is the velocity in m/s

since m is the total mass, m = mA + mB, we can write the equation as:

mA vA + mB vB = (mA + mB) v

furthermore, car B was at a stop signal therefore vB = 0, hence

mA vA + 0 = (mA + mB) v

1800 (vA) = (1800 + 1500) (7.1 m/s)

vA = 13.02 m/s

The sprinter's final speed is calculated using Newton's second law and kinematic equations, resulting in a final speed of 7.43 m/s based on the provided force exerted and the time duration.

The question involves calculating the final speed and distance traveled by a sprinter, which is a physics concept involving Newton's second law of motion and the basic principles of kinematics. To find the sprinter's final speed, we use the relationship derived from Newton's laws that connects force, mass, acceleration, and velocity. Given that the sprinter exerts an average force of 650 N backward on the ground for 0.800 s, and has a mass of 70.0 kg, we can calculate the acceleration and then use it to find the final speed.

First, we calculate the acceleration using Newton's second law, F = ma. The force exerted on the ground is equal and opposite to the force exerted on the sprinter (Newton's third law), so:

Acceleration, a = F/m = 650 N / 70.0 kg = 9.29 m/s2

Then, we use the equation of motion, v = u + at, where u is the initial velocity (0 m/s, as the sprinter starts from rest), a is the acceleration, and t is the time. Substituting the values, we get the final speed:
Final speed, v = 0 + (9.29 m/s2 × 0.800 s) = 7.43 m/s

This question is just so simple. All we have to do to get the wavelength is to divide the length by the number of waves.

Wavelength = 20 cm / 80 waves

Wavelength = 0.25 cm / wave = 0.25 cm

Or if in meters, Wavelength = 2.5 x 10^-3 m

The answer is D I took the test

Answer:

Light ray will bend inwards and pass through the focus on principle axis after reflection

Explanation:

As we know that for curved mirror the equation is given as

[tex]\frac{1}{d_i} + \frac{1}{d_0} = \frac{1}{f}[/tex]

now here we know that initially light is travelling parallel to principle axis for given concave mirror.

So here the object position must be at very large distance from the mirror

[tex]d_0[/tex] = infinite

so here by above equation we will have

[tex]\frac{1}{d_i} + \frac{1}{infinite} = \frac{1}{f}[/tex]

now from this equation we can say

[tex]d_i = f[/tex]

so position of image will be at focus of mirror which means the parallel light will pass through focus after reflection from mirror.

Final answer:

The greatest danger on expressways is often the combination of high speeds, aggressive driving, and other driving behaviors that can lead to severe accidents. Patience and safe driving practices are crucial to avoid these dangers. The scenario provided demonstrates an example of aggressive driving that could pose a risk on the expressway.

Explanation:

When driving on an expressway, the greatest danger often arises from high speeds combined with factors such as driver behavior, environmental conditions, and vehicle performance. High-speed environments increase the potential severity of any accident that may occur. Furthermore, situations involving aggressive driving, such as tailgating, improper lane changes, or the act of speeding itself, can lead to collisions. For example, like the scenario of Peter who became frustrated with a slower driver and engaged in tailgating and horn honking, it is essential to practice safe driving behaviors and be patient to avoid accidents.

Regarding the scenario about the rabbit crossing the expressway, if the car is traveling in the furthest lane from the rabbit, there is no guarantee the rabbit would be able to cross all three lanes safely. It is unpredictable due to the potential for multiple vehicles and varying speeds. Animal crossings on highways are hazardous and often result in accidents.

To solve this problem, we should remember that the formula for index of refraction is defined as:

n = c / v

or

n v = c

Where,

n = index of refraction

c = speed of light

v = speed of light in the medium

Since speed of light is constant, then we can simply equate the materials 1 and 2:

n1 v1 = n2 v2

Where the speed of light in the medium (v) can be expressed as:

v = w * f

Where,

w = wavelength of light

f = frequency of light

Therefore substituting this back into the relating equation:

n1  w1 f1 = n1  w2 f1

Since it is given that the light is monochromatic, w1 = w2, this further simplifies the equation to:

n1 f1 = n2 f2

f1 / f2 = n2 / n1                  (ANSWER)

The ratio of the frequency of light in two different materials can be found using their refractive indices and the equation n1*f1 = n2*f2.

The ratio of the frequency of light in two different materials is determined by their refractive indices.

In physics, the frequency of light can be related to the speed of light in different media using the index of refraction.

The equation n1*f1 = n2*f2 expresses the relationship between the frequencies of light in material 1 and material 2.

The ratio of frequencies f1/f2 of monochromatic light when moving from one material to another is 1, because the frequency of light remains constant across different media.

The student asks about the ratio of the frequencies f1 and f2 of monochromatic light going from one material with index of refraction n1 to another with index of refraction n2. This question pertains to the physics concept of refraction and properties of light as it travels through different media. The frequency of light does not change when it passes from one medium to another, as frequency is an intrinsic property of the wave that is independent of the medium. Therefore, the ratio of the frequencies f1/f2 is equal to 1, or f1=f2.

Answer:

A, B and C

Explanation:

An object thrown with a speed at some angle near the Earth undergoes a projectile motion. It moves in a curved path under the action of gravity only. The object is known as projectile.  options A, B and C are examples of projectile motion. These objects move under the action of gravity only.

An airplane landing is in control of its motion and does not move just under the action of gravity. So, it cannot be considered as projectile motion.

Answer:

Option 2 and 3

Explanation:

When the net force on the car is zero, the acceleration is also zero.

Along horizontal direction, the net force is zero. It means the car is moving with fixed speed and same direction.

Along vertical direction, the weight of the car is balanced by the normal reaction.

When the car is parked, the weight of the car is balanced by the normal reaction.

You should deflect the ball in order to maximize your speed on the skateboard.

Since this creates a larger impulse, you want to deflect the ball. Splitting it up into catching and throwing the ball may by something you can think of deflecting the ball. First, you need to catch the ball, which in turn would push you forward with some speed. (The speed we are talking about should obviously be equal to option A, where you catch the ball). Now, throw the ball back to him since these two processes are equal to deflecting the ball. Throwing a mass away from you would cause or enable you to move even fast.

Any red opaque object reflects red light only.

An opaque object is such that no light is able to pass through it.

Given is a red opaque object.

Red opaque object reflects red light only.

Therefore, any red opaque object reflects red light only.

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The statement is false because wave speed is not computed by squaring the wave's amplitude. The speed of a wave is influenced by the medium's properties and is often the square root of an elastic property to an inertial property ratio.

The statement 'to calculate the wave speed of a wave square the amplitude of the wave' is false. Wave speed is not calculated by squaring the amplitude of the wave. Instead, wave speed is determined by the properties of the medium through which the wave is traveling and can generally be expressed as the square root of the ratio of an elastic property to an inertial property of the medium.

For example, the speed of sound in air is approximately given by 343.00 m/s at 20°C. The energy and power of a wave, on the other hand, are proportional to the square of the amplitude, but this is not used to calculate the wave's speed.

Therefore, the terms 'amplitude of a wave' and 'wave speed' refer to different aspects of wave properties and should not be confused with each other in physical calculations.

Complete Question:

True or false. To calculate the wave speed of a wave, square the amplitude of the wave.

When waiting to turn left and a car is approaching from the opposite direction with a turn signal, you should wait until the other car starts its turn before making yours (a). This applies regardless of whether they signal a left or right turn.

In the situation where you are waiting to turn left into a small parking lot and a car is approaching from the opposite direction with a turn signal on, you need to exercise caution. It's important to note that you should wait until the other car starts its turn (a) before making your turn. This is applicable whether the driver is signaling for a left turn or a right turn. You should never make assumptions based on signal indicators as drivers might sometimes forget to turn them off or mistakenly leave them on.

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To calculate how far a 68 kg person could walk at 5 km/h based on the energy from an energy bar, you need to know the energy content of the bar. Then, you would estimate the energy expenditure during walking and use that to estimate the distance that person could cover.

Your question refers to energy and distance covered by a person walking at a certain speed, making it a topic of Physics. However, the computation of how far a 68 kg person can walk at 5 km/h, given a certain amount of energy (derived from an energy bar), requires more information.

We would specifically need to know the amount of energy provided by the energy bar. Once we have that, we can dive into understanding that energy consumption during physical activity, like walking, is determined by body mass and speed among other factors.

A common estimation of energy expenditure due to walking is made using the formula 0.1×weight(kg)×distance(km). After obtaining the energy content of the bar, we can rearrange that formula to find the distance: distance = energy/(0.1×weight). With that calculation, you could answer how far the person can walk based on the energy released by the bar.

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Answer:

The two are still synchronized but run slow

Explanation:

Time flows at a different rate for an object that is moving. The time of the object which is moving is running slower than an object which is stationary. Here, Albert is stationary so time will flow faster for him and for Henry who is moving time will flow slower. This phenomenon is called time dilation

[tex]\Delta t'=\frac{\Delta t}{\sqrt{1-\frac{v^2}{c^2}}}[/tex]

Where,

Δt is the time elapsed for the person who is moving

Δt' is the time elapsed for the person who is stationary

c = Speed of light = 3×10⁸ m/s

v = Velocity of the object which is moving

Answer: D

Explanation:  

The two are still synchronized but run slow.