A train changes its velocity from 70km / h to 20km / h in 6 s The distance it covered is:
a) 75.0 m
b) 9.87 m
c) 15.4 m
d) 20.6 m

Sound waves are a type of mechanical wave that propagate through a medium, typically air but also other materials such as water or solids.

Frequency: the frequency of a sound wave refers to the number of cycles or vibrations it completes per second and is measured in Hertz (Hz).

Amplitude: the amplitude of a sound wave refers to the maximum displacement or intensity of the wave from its equilibrium position. It represents the loudness or volume of the sound, with larger amplitudes corresponding to louder sounds and smaller amplitudes corresponding to softer sounds.

Wavelength: the wavelength of a sound wave is the distance between two consecutive points in the wave that are in phase, such as from one peak to the next or one trough to the next. It is inversely related to the frequency of the wave.

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The magnitude of the force on the tooth is approximately 0.022 N.

To find the magnitude and direction of the force on the tooth, we can use Hooke's Law, which states that the force exerted on an object is directly proportional to the change in length of a material when it is stretched or compressed.

First, we need to calculate the strain (ε) of the stainless-steel wire.

Strain is defined as the change in length divided by the original length:

ε = ΔL / L₀

Given that the change in length (ΔL) is 0.10 mm \((0.10 \times 10^{-3} m)\) and the unstretched length (L₀) is 3.1 cm \((3.1 \times 10^{-2} m)\), we can calculate the strain:

\(\epsilon=(0.10 \times 10^{-3} m)/(3.1 \times 10^{-2} m)=0.003225\)

Next, we can use Young's modulus (E) to calculate the stress (σ) in the wire.

Stress is defined as the force per unit area:

σ = E * ε

Given that Young's modulus (E) for stainless-steel is 18 × 10¹⁰ N/m², we can calculate the stress:

σ = (18 × 10¹⁰ N/m²) * 0.003225 = 5.805 × 10⁸ N/m²

Now, we can find the force (F) on the tooth by multiplying the stress by the cross-sectional area (A) of the wire:

F = σ * A

The cross-sectional area (A) can be calculated using the formula for the area of a circle:

A = π * (d/2)²

Given that the diameter (d) of the wire is 0.22 mm\((0.22 \times 10^{-3} m)\), we can calculate the cross-sectional area:

\(A = \pi * (0.22 \times 10^-3 m / 2)^{2} = 3.802 \times 10^{-8} m^2\)

Finally, we can calculate the force:

\(F = (5.805 \times 10^{8} N/m^{2}) * (3.802 \times 10^-8 m^{2}) \approx 2.206 \times 10^{-2} N\)

Therefore, the magnitude of the force on the tooth is approximately 0.022 N.

Since the wire is stretched, the force is pulling the tooth in the direction opposite to the stretching.

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The value of acceleration is 3 m/s2.

Our body makes every effort to open up our airways. When sneezing, the diaphragm, abdomen, vocal cord, and chest muscles all work together. As a result, the air leaving our lungs accelerates rapidly.

Change in velocity, Δv

Change in time, Δt

Note that

1 km = 1000 m

1 h = 3600 s

Therefore

Δv = (125,000 m/h)*(1/3600 h/s) = 3 m/s2.

Therefore, The value of acceleration is 3 m/s2.

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A cell of inter resistance of 0.5 ohm is connected to coil of resistance 4 ohm and 8 ohm joined in parallel.If there is current of 2A in 8 ohm, the electromotive force (emf) of the cell is approximately 14.5 volts.

To find the emf of the cell, we can apply Ohm's Law and Kirchhoff's laws to analyze the circuit.

Given:

Resistance of the coil, R1 = 4 ohm

Resistance of the other resistor, R2 = 8 ohm

Current passing through the 8-ohm resistor, I = 2A

First, let's analyze the parallel combination of the 4-ohm and 8-ohm resistors.

The total resistance of two resistors in parallel can be calculated using the formula:

1/Rp = 1/R1 + 1/R2

Substituting the given values, we have:

1/Rp = 1/4 + 1/8

1/Rp = 2/8 + 1/8

1/Rp = 3/8

Rp = 8/3 ohm

Now, let's consider the total resistance in the circuit, which includes the internal resistance of the cell (0.5 ohm) and the parallel combination of the resistors (8/3 ohm).

R_total = R_internal + Rp

R_total = 0.5 + 8/3

R_total = 1.833 ohm

Now, we can find the emf of the cell using Ohm's Law:

emf = I * R_total

emf = 2 * 1.833

emf ≈ 3.667 volts

Therefore, the emf of the cell is approximately 3.667 volts.

However, it is worth noting that the given current of 2A passing through the 8-ohm resistor does not affect the emf calculation since the emf of the cell is independent of the current in the circuit.

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Answer:

The frictional force is the other component; it is in a direction parallel to the plane of the interface between objects. ... When a frictional force exists but there is no relative motion of the surfaces in contact (e.g., the book isn't sliding across the table), we call it a static frictional force.

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Explanation:

Answer:

To determine the height to which the ball rises before it reaches its peak, we need to know the initial velocity of the ball and the acceleration due to gravity. Let's assume the initial velocity of the ball is v and the acceleration due to gravity is g.

The time it takes for the ball to reach its peak is one-half the total hang-time, or 1/2 * 6.25 s = 3.125 s.

The height to which the ball rises can be calculated using the formula:

height = v * t - (1/2) * g * t^2

Substituting in the values we know, we get:

height = v * 3.125 s - (1/2) * g * (3.125 s)^2

To solve for the height, we need to know the value of v and g. Without more information, it is not possible to determine the height to which the ball rises before it reaches its peak.

Explanation:

Answer:

Approximately \(47.9\; {\rm m}\) (assuming that \(g = 9.81\; {\rm m\cdot s^{-2}}\) and that air resistance on the baseball is negligible.)

Explanation:

If the air resistance on the baseball is negligible, the baseball will reach maximum height at exactly \((1/2)\) the time it is in the air. In this example, that will be \(t = (6.25\; {\rm s}) / (2) = 3.125\; {\rm s}\).

When the baseball is at maximum height, the velocity of the baseball will be \(0\). Let \(v_{f}\) denote the velocity of the baseball after a period of \(t\). After \(t = 3.125\; {\rm s}\), the baseball would reach maximum height with a velocity of \(v_{f} = 0\; {\rm m\cdot s^{-1}}\).

Since air resistance is negligible, the acceleration on the baseball will be constantly \(a = (-g) = (-9.81\; {\rm m\cdot s^{-2}})\).

Let \(v_{i}\) denote the initial velocity of this baseball. The SUVAT equation \(v_{f} = v_{i} + a\, t\) relates these quantities. Rearrange this equation and solve for initial velocity \(v_{i}\):

\(\begin{aligned}v_{i} &= v_{f} - a\, t \\ &= (0\; {\rm m\cdot s^{-1}}) - (-9.81\; {\rm m\cdot s^{-2}})\, (3.125\; {\rm s}) \\ &\approx 30.656\; {\rm m\cdot s^{-1}}\end{aligned}\).

The displacement of an object is the change in the position. Let \(x\) denote the displacement of the baseball when its velocity changed from \(v_{i} = 0\; {\rm m\cdot s^{-1}}\) (at starting point) to \(v_{t} \approx 30.656\; {\rm m\cdot s^{-1}}\) (at max height) in \(t = 3.125\; {\rm s}\). Apply the equation \(x = (1/2)\, (v_{i} + v_{t}) \, t\) to find the displacement of this baseball:

\(\begin{aligned}x &= \frac{1}{2}\, (v_{i} + v_{t})\, t \\ &\approx \frac{1}{2}\, (0\; {\rm m\cdot s^{-1}} + 30.565\; {\rm m\cdot s^{-1}})\, (3.125\; {\rm s}) \\ &\approx 47.9\; {\rm m}\end{aligned}\).

In other words, the position of the baseball changed by approximately \(47.9\; {\rm m}\) from the starting point to the position where the baseball reached maximum height. Hence, the maximum height of this baseball would be approximately \(47.9\; {\rm m}\!\).

Answer:

The paper focuses on the biology of stress and resilience and their biomarkers in humans from the system science perspective. A stressor pushes the physiological system away from its baseline state toward a lower utility state. The physiological system may return toward the original state in one attractor basin but may be shifted to a state in another, lower utility attractor basin. While some physiological changes induced by stressors may benefit health, there is often a chronic wear and tear cost due to implementing changes to enable the return of the system to its baseline state and maintain itself in the high utility baseline attractor basin following repeated perturbations. This cost, also called allostatic load, is the utility reduction associated with both a change in state and with alterations in the attractor basin that affect system responses following future perturbations. This added cost can increase the time course of the return to baseline or the likelihood of moving into a different attractor basin following a perturbation. Opposite to this is the system's resilience which influences its ability to return to the high utility attractor basin following a perturbation by increasing the likelihood and/or speed of returning to the baseline state following a stressor. This review paper is a qualitative systematic review; it covers areas most relevant for moving the stress and resilience field forward from a more quantitative and neuroscientific perspective.

Explanation:

During a normal reaction to a stressful event, muscles are moved to their maximum capacity, and sensitivity is increased.

This is defined as the ability of an organism to respond to stimuli such as touch, sensation etc.

During exercise, sensitivity to substances such as insulin when glucose transport wears off helps to balance energy supply.

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Answer: C

Explanation: student 1 has a vel to the right

The path of the falling stone relative to student 1 is straight down while it is parabolic to student 2.

Motion can be defined as a change in the location (position) of a physical object or body with respect to a reference point, especially due to the action of an external force.

As shown in the image attached below, the path of the falling stone relative to student 1 is straight down while it is parabolic to student 2 because student 1 is standing on a cart that is moving at a constant speed and student 2 is stationary i.e standing at rest on the ground.

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Answer:Magnetic fields from two sources add up as vectors at each point, so the strength of the field is not necessarily the sum of the strengths1. Magnetic fields are vectors, which means they have direction as well as size. Therefore, the sum of two magnetic fields is not simply the sum of their magnitudes2.

Explanation:

Answer:

Temporary magnets are made from soft metals, and only retain their magnetism while near a permanent magnetic field or electronic current. ... They lose their magnetism gradually when the magnetic field is removed.

Explanation:

hope its help you....

Answer:

Electromagnetic Induction by a Moving Magnet

Then the action of moving a coil or loop of wire through a magnetic field induces a voltage in the coil with the magnitude of this induced voltage being proportional to the speed or velocity of the movement.

Explanation:

Answer:

Explanation:

The speed is the same coming back down to the ground as it would be when thrown up.

A little later, you will be studying energy. One of the things conserved in a system is energy. You cannot get more energy out of a system than you have put in.

That fact explains how the speed at the end of the object's travels can be the same as the beginning. All energy must be accounted for.

The second part is not so easily proved or even shown easily. It can be indicated, though.

Suppose vi = 40 m/s

Suppose vf = 0 m/s                 In other words, you throw a rock up and you stop timing it when it reaches its maximum height.

a = - 9.81                                  Gravity goes in the opposite direction to vi

vf = vi^2 + 2*a*d

0 = 1600 - 2*9.81*d

-1600 = -19.62*d

1600 / 19.62 = d

d = 81.55 m.

Now leave everything else alone and double vi

0 = 80^2 - 2*9.81 d

-6400 = -19.62 * d

d = 326.2

Give or take a bit, the height = roughly 4 times what it was if the initial speed is doubled.  326.2 / 81.55 = 4

Answer:

Because they are so close, than can collide very quickly, i.e. it takes less time for a molecule of the solid to 'bump' into its neighborough. Solids are packed together tighter than liquids and gases, hence sound travels fastest in solids.

Answer:

Answer A is the correct one

Explanation:

The force of gravity is pulling down in the orange, while the force of resistance with the air is pushing up on the orange. This last force could be viewed as a type of "friction" force with the air.

A) The force of gravity is pulling down in the orange, while the force of friction is pushing up on the orange

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Answer:

Resistance is inversly proportional to the current.

V=I.R.

P=V.I

Answer: 0.50 m/s

Explanation: it’s on khan academy this was the correct answer

An energetic child runs forward and backward. Its motion is shown on the following graph of horizontal position x vs. time t.

What is the instantaneous speed of the child at t = 10 s?

Answer:

Answer: 0.50 m/s

The period of the simple harmonic motion of the center of mass of the two spheres is approximately 0.770 seconds.

To find the period of the simple harmonic motion of the center of mass of the two spheres, we need to use the equation for the period of a mass-spring system:

T = 2π√(m/k)

where T is the period, m is the total mass of the system (two spheres), and k is the spring constant.

First, we need to find the total mass of the system:

m = 2m1 = 2(0.852 kg) = 1.704 kg

where m1 is the mass of one sphere.

Next, we need to find the spring constant:

k = 153 N/m

Now, we can calculate the period:

2π√(1.704 kg/153 N/m) ≈ 0.770 s

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Galileo challenged the Aristotelian-Ptolemaic model, providing support for the heliocentric model and paving the way for a new understanding of the universe.

Galileo Galilei played a crucial role in challenging the prevailing geocentric model of the universe proposed by Aristotle and supported by Ptolemy. He provided several lines of evidence that effectively disproved their theories and supported the heliocentric model proposed by Nicolaus Copernicus. Some of the key evidence used by Galileo includes:

1. Observations through a telescope: Galileo was one of the first astronomers to use a telescope to observe the heavens. His telescopic observations revealed several important discoveries that contradicted the Aristotelian-Ptolemaic worldview. He observed the phases of Venus, which demonstrated that Venus orbits the Sun and not Earth. He also observed the four largest moons of Jupiter, now known as the Galilean moons, which provided evidence for celestial bodies orbiting a planet other than Earth.

2. Sunspots: Galileo's observations of sunspots provided evidence that the Sun is not a perfect celestial body, as suggested by Aristotle. Sunspots indicated that the Sun has imperfections and undergoes changes, challenging the notion of celestial perfection.

3. Mountains on the Moon: Galileo observed the rugged and uneven surface of the Moon, which contradicted Aristotle's belief in celestial spheres made of perfect, unchanging material. The presence of mountains on the Moon suggested that celestial bodies are subject to the same physical laws as Earth.

4. Phases of Venus: Galileo's observations of the phases of Venus provided direct evidence for the heliocentric model. As Venus orbits the Sun, it goes through phases similar to the Moon, ranging from crescent to full. This observation strongly supported the idea that Venus revolves around the Sun.

These lines of evidence presented by Galileo challenged the Aristotelian-Ptolemaic model, providing support for the heliocentric model and paving the way for a new understanding of the universe. His work marked a significant turning point in the history of science and laid the foundation for modern astronomy.

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Answer:

Answers are in the explanation

Explanation:

a)

vf² = vi² + 2gh

0 = vi² + 2(-9.8)(72)

vi = 37.57 m/s

b)

vf = vi + gt

0 = 37.57 - (9.8)t

t = 3.83 s

3.83 x 2 = 7.67 s

vf = vi + gt

vf = 37.57 - (9.8)(7.67)

vf = -37.60 m/s

c)

Its vertical velocity at the highest point is 0 m/s

The near point of a human eye is about a distance of 25 cm.

The closest distance that an object may be viewed clearly without straining is known as the near point of the eye.

This distance (the shortest at which a distinct image may be seen) is 25 cm for a typical human eye.

The closest point within the accommodation range of the eye at which an object may be positioned while still forming a focused picture on the retina is also referred to as the near point.

In order to focus on an item at the average near point distance, a person with hyperopia must have a near point that is further away than the typical near point for someone of their age.

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Answer:

0.182C

Explanation:

Using Q= It

= 13x10^3 . 14x10^-6

= 0.182C

Answer:

stopping potential is the negative potential applied to the circuit to stop the moving electrons so as to stop the flow of current

for high current high negative potential is applied

Answer:

A sound box or sounding box (sometimes written soundbox) is an open chamber in the body of a musical instrument which modifies the sound of the instrument, and helps transfer that sound to the surrounding air. Objects respond more strongly to vibrations at certain frequencies, known as resonances.

Explanation:

Answer: \(32.65\ m\)

Explanation:

Given

mass of laptop m=2 kg

The velocity of car u=8 m/s

The coefficient of static friction is \(\mu_s=0.4\)

The coefficient of kinetic friction is \(\mu_k=0.2\)

As the car is moving, so the coefficient of kinetic friction comes into play

deceleration offered by friction \(\mu_kg=0.2\times 9.8\ m/s^2\)

Using the equation of motion \(v^2-u^2=2as\\\)

insert the values

\(0^2-8^2=2(-0.2\times 9.8)s\\\\s=\dfrac{64}{1.96}\\\\s=32.65\ m\)

Answer;

1. Accuracy is the closeness with which an instrument approaches the true value of the quantity being measured

2. Precision is a measure of the reproducibility of the measurement

3. Accuracy may be specified in terms of limits of errors.