A moving car initially has kinetic energy K. The car then moves in the opposite direction with four times its initial speed. What is the kinetic energy now

Explanation:

Which of the following electromagnetic waves is used in medicine to destroy cancer cells?

A. IR rays

B. Visible rays

C. Gamma rays

D. Ultraviolet rays

Answer

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Hint: Electromagnetic rays that have a high frequency and highest-energy photons such that their energy is enough to penetrate several centimetres of lead is used to destroy cancer cells.

Complete step by step answer:

Electromagnetic waves with wavelengths shorter than about 100-trillionths of a meter are called gamma rays. They are used in a technique called radiation therapy to kill diseased cells in the human body. A beam of gamma rays can damage the biological molecules in living cells, causing both healthy and diseased cells to die. By carefully controlling the amount of gamma ray radiation and focusing it on the diseased area, the damage to healthy cells can be reduced during treatment.

So, the correct answer is “Option C”.

Additional Information: A. Infrared rays are used to form images of objects. Remote control and CD-drives also used infrared waves.

B. Visible light is the light that we can detect with our eyes. The spectrum of visible light shows all colours of light from long wavelength red to short wavelength violet.

D. Ultraviolet rays provide vitamin D for the body. They are also used to disinfect food, water and medical supplies. If Ultraviolet rays enter a cell, they can damage the DNA.

Note: Apart from Gamma rays, X-rays are also used in radiation therapy to kill diseased cells in the human body. X-rays are also used to form images of bones and teeth and in airport screening devices to examine contents of luggage.

hope this passage helps I don't know Its correct answer ..... its from my school PDF

Answer:

Gamma rays

Explanation:

NOTE: The higher the frequency of the radiation, the more damage it is likely to cause to the body: infrared radiation is felt as heat and causes skin to burn.

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Answer:

Explanation:

Terminal speed is

2 m/s²(3 s) = 6 m/s

30 m / 6 m/s = 5 s

total sink time is

3 + 5 = 8 s

The total time taken by the rock to sink would be 8 seconds

The total displacement covered by any object per unit of time is known as velocity. It depends on the magnitude as well as the direction of the moving object.

The acceleration of the rock for the first three seconds = 2 meters/second²

The time taken to reach the terminal velocity = 3 seconds

terminal velocity = 2 ×3

                           = 6 meters/second²

The time for which the rock sink at terminal velocity = 30 /6

                                                                                       = 5 seconds

total time is taken by the rock to sink = 3 + 5

                                                           =8 seconds

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Answer:

Explanation:

Q1) d) A is not correct; R is correct (sort of) but is not the reason for A.

A vector may be resolved into an infinite number of components.

Breaking a projectile motion into the vertical and horizontal components is the EASIEST way to solve it because acceleration can be assumed to be constant in both directions. Zero for horizontal and g(ravity) in the vertical. However it is not the ONLY way to do it. Other ways are much more complex.

Q2) a) Both A and R are correct; R is the correct explanation of A  (sort of)

A is correct. Speed is constant in uniform circular motion.

R is correct if you call CENTRIPETAL acceleration constant. It is only constant in magnitude. The direction is always changing as the vector always points toward the center of rotation.

Answer: part a is e

part b a  

Explanation:

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42.9°

Explanation:

Let's assume that the x-axis is aligned with the incline and the positive direction is up the incline. We can then apply Newton's 2nd law as follows:

[tex]x:\;\;\;\;F - mg\sin{\theta} = 0\;\;\;\;[/tex]

[tex]\Rightarrow mg\sin{\theta} = F[/tex]

Note that the net force is zero because the block is moving with a constant speed when the angle of the incline is set at [tex]\theta.[/tex] Solving for the angle, we get

[tex]\sin{\theta} = \dfrac{F}{mg}[/tex]

or

[tex]\theta = \sin^{-1}\left(\dfrac{F}{mg}\right)[/tex]

[tex]\;\;\;= \sin^{-1}\left[\dfrac{34\:\text{N}}{(5.1\:\text{kg})(9.8\:\text{m/s}^2)}\right][/tex]

[tex]\;\;\;=42.9°[/tex]

Explanation:

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Answer:

Explanation:

If air resistance is ignored, the water travels for a time of

t = d/v = 20 m / 5 m/s = 4 s

falling from vertical rest, the water strikes the wall a distance below the hose

d = ½gt² = ½(10)4² = 80 m

Yeah, I think ignoring air resistance is wishful thinking considering the time and distances involved.

A solvent is any substance which is able to interact with a solute and dissolve it.

A solute is any substance that is able to interact with a solvent and dissolve in it. Usually, the solute must posses similar intermolecular forces as the solvent.

For this reason, polar solutes dissolve in polar solvents while nonpolar solutes dissolve in nonpolar solvents. In polar solutes, the ions or dipoles of the solute are able to interact with the dipoles of the solvent thereby pulling the solute particles apart in order to have solvent - solute interaction.

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Answer:

900N, charges repel

Explanation:

F = KQq/d²

K = 9 × 10^9Nm²/C²

Q= 10mC = 10 × 10^-3C

q = 1mc = 1 × 10^-3C

d = 10m

F = ?

Force = (9 × 10^9 × 10 × 10^-3 × 1 × 10^-3)/10²

= 9 × 10²

= 900N

It will be an electrostatic force of repulsion since like charges(two positive charges) repel

The magnitude and the direction of the electrostatic force between the charges will be 900N and the charges will repel each other.

Coulomb's law states that whenever the two charged particles are separated by a particular distance then there will be a force of attraction or repulsion acts between the charge.

The formula of coulomb's force will be given by

[tex]F=k\dfrac{q_1q_2}{d^2}[/tex]

[tex]K=9\times 10^9\ \frac{Nm^2}{C^2}[/tex]

[tex]q_1= 10\times 10^{-3}\ C[/tex]

[tex]q_2=1\times 10^{-3}\ C[/tex]

[tex]\rm Distance \ d=10 \ m[/tex]

Now the force will be calculated as

[tex]F=(9\times 10^9)\dfrac{(10\times 10^{-3})\times (1\times 10^{-3})}{10}[/tex]

[tex]F= 900\ N[/tex]

The charges are positive in nature so they will repel each other

Hence the magnitude and the direction of the electrostatic force between the charges will be 900N and the charges will repel each other.

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Answer:

[tex]\boxed {\boxed {\sf 36 \ meters}}[/tex]

Explanation:

We are asked to find the distance a body covers. We know the initial velocity, acceleration, and time, so we will use the following kinematic equation.

[tex]d= v_i t+ \frac {1}{2} \ at^2[/tex]

The body starts at rest with an initial velocity of 0 meters per second. The acceleration is 8 meters per second squared. The time is 3.0 seconds.

Substitute the values into the formula.

[tex]d= (0 \ m/s)(3 \ s) + \frac{1}{2} (8 \ m/s^2)(3 \ s)^2[/tex]

Multiply the first set of parentheses.

[tex]d= ( 0 \ m/s * 3 \ s) + \frac{1}{2} ( 8 \ m/s^2)(3 \ s)^2[/tex]

[tex]d=0 \ m + \frac{1}{2} ( 8 \ m/s^2)(3 \ s)^2[/tex]

Solve the exponent.

[tex]d= 0 \ m + \frac{1}{2}( 8 \ m/s^2)(9 \ s^2)[/tex]

Multiply again.

[tex]d= 0 \ m + \frac{1}{2} ( 72 \ m)[/tex]

[tex]d= 36 \ m[/tex]

The body will cover a distance of 36 meters.

Answer:

I think it's a chemical change.

Answer:

3,958.8 mi

Explanation:

Answer:

Earth's magnetic field (and the surface magnetic field) is approximately a magnetic dipole, with the magnetic field S pole near the Earth's geographic north pole (see Magnetic North Pole) and the other magnetic field N pole near the Earth's geographic south pole (see Magnetic South Pole). This makes the compass usable for navigation. The cause of the field can be explained by dynamo theory. A magnetic field extends infinitely, though it weakens with distance from its source. The Earth's magnetic field, also called the geomagnetic field, which effectively extends several tens of thousands of kilometres into space, forms the Earth's magnetosphere. A paleomagnetic study of Australian red dacite and pillow basalt has estimated the magnetic field to be at least 3.5 billion years old

Answer:

[tex]0.2\; {\rm T}[/tex], assuming that the speed of the electron stays the same.

Explanation:

Let [tex]v[/tex] denote the speed of this electron. Let [tex]q[/tex] denote the electric charge on this electron. Let [tex]m[/tex] denote the mass of this electron.

Since the path of this electron is a circle (not a helix,) this path would be in a plane normal to the magnetic field.

Let [tex]B[/tex] denote the strength of this magnetic field. The size of the magnetic force on this electron would be:

[tex]F = q\, v\, B[/tex].

Assuming that there is no other force on this electron. The net force on this electron would be [tex]F = q\, v\, B[/tex]. By Newton's Second Law of motion, the acceleration of this electron would be:

[tex]\begin{aligned}a &= \frac{F}{m} \\ &= \frac{q\, v\, B}{m}\end{aligned}[/tex].

On the other hand, since this electron is in a circular motion with a constant speed:

[tex]\begin{aligned} a = \frac{v^{2}}{r} \end{aligned}[/tex].

Combine the two equations to obtain a relationship between [tex]r[/tex] (radius of the path of the electron) and [tex]B[/tex] (strength of the magnetic field:)

[tex]\begin{aligned}\frac{q\, v\, B}{m} = \frac{v^{2}}{r}\end{aligned}[/tex].

Simplify to obtain:

[tex]\begin{aligned}r &= \frac{m\, v^{2}}{q\, v\, B} \\ &= \frac{m\, v}{q\, B} \\ &= \left(\frac{m\, v}{q}\right)\, \frac{1}{B}\end{aligned}[/tex].

In other words, if the speed [tex]v[/tex] of this electron stays the same, the radius [tex]r[/tex] of the path of this electron would be inversely proportional to the strength [tex]B[/tex] of the magnetic field. Doubling the radius of this path would require halving the strength of the magnetic field (to [tex]0.2\; {\rm T}[/tex].)

The amount of work done by the hairdryer is equal to 450 Kilojoules.

Given the following data:

To determine the amount of work done by the hairdryer:

Mathematically, the work done by an object with respect to power and time is given by the formula:

[tex]Work\;done = power \times time[/tex]

Substituting the given parameters into the formula, we have;

[tex]Work\;done = 750 \times 600[/tex]

Work done = 450,000 Joules

Note: 1000 Joules = 1 Kilojoules.

Work done = 450 Kilojoules.

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Answer:

mid-ocean oceanic ridges

Explanation:

Answer:

mid-ocean oceanic ridges

Explanation:

Divergent boundaries are most likely to be found at mid-oceean oceanic ridges.

Answer:

A closed organ pipe is λ/4  (node-antinode) long.

λ = speed / frequency = 331.5 / 259.6 = 1.28 m

λ/4 = .319 m     length of closed pipe

An open pipe has a fundamental wavelength of A-N-A or λ/2

The second harmonic would be A-N-A-N-A   or   λ = 1.28 m for the second harmonic   331.5 / 259.6 = 1.28  (the fundamental would be 331.5 / .628

The final position of the object after 2 s is 11 m.

Motion: This can be defined as the change in position of a body.

⇒ Formula:

⇒ Where:

From the question,

⇒ Given:

⇒ Substitute these values into equation 1

Hence, The final position of the object after 2 s is 11 m

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The magnitude of the induced electrical field is 0.0015V/m, the field is pointing towards the clockwise direction while the current in the ring will be 0.0002355A if the resistance is 4 ohms. The emf between point a and b is zero and the EMF across the point if they're slightly separated between the ends is 0.000942V

To solve this question, we would have to go about each one individually

Data:

[tex]r=10cm=0.1m\\[/tex]

a.

The magnitude of the induced electrical field at any point within the radius is

[tex]\int\limits^a_b {E} \, du=\frac{dU}{dt}=\pi \frac{dB}{dt}=\pi r^{2}\frac{dB}{dt}\\E*2\pi r=\pi r^{2}\frac{dB}{dt} \\E=\frac{r}{2}\frac{dB}{dt}=\frac{0.1}{2}*0.03=0.0015V/m[/tex]

b.

The field is pointing towards the clockwise direction.

c.

The current in the ring if we are given a resistance of 4ohms

[tex]I=\frac{emf}{R}=\frac{\pi r^{2}\frac{dB}{dt} }{R} =\frac{\pi (0.1)^2*0.03}{4} =0.0002355A[/tex]

d.

The emf between point a and b is zero

e.

The EMF across two points if they're separated by small distance across the ring is

we would use the formula to solve for the EMF

[tex]E=\pi r^{2}\frac{dB}{dt}=\pi (0.1)^2*0.03=0.000942V[/tex]

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Explanation:

This question is not feasible. There is no way to calculate the energy needed because the question is missing the final temperature

Answer:

An electron tube from which all air has been removed. The vacuum ensures transparency inside the tube for electric fields and moving electrons. Most electron tubes are vacuum tubes; cathode-ray tubes, which include television picture tubes and other video display tubes, are the most widely used vacuum tubes

Explanation:

hope it help

Answer:

Single Displacement Reaction

Explanation:

Here, only one element is getting replaced during the reaction, that is, silver gets replaced by copper, hence, single displacement reaction.

Hope it helps :)

Answer:

Explanation:

Ignoring friction, the initial kinetic energy will convert to maximum potential energy at its highest point.

PE = KE

mgh = ½mv²

    h = v²/2g

    h = 36.4²/ (2(9.81))

    h = 67.53109...

    h = 67.53 m

A force of 50 N was applied to an object with a mass of 5 kg, then the acceleration of the object will be 10 m/s².

The rate of change in an object's velocity with respect to time is known as acceleration in mechanics. The vector quantity of accelerations. The direction of the net force that is acting on an object determines its acceleration.

Since acceleration has both a magnitude and a direction, it is a vector quantity. Velocity is a vector quantity as well. The definition of acceleration is the change in velocity vector over a time interval divided by the time interval.

There are several types of acceleration :

According to the question, the given values are :

Force, F = 50 N

Mass, m = 5 kg

Force = m × a

a = 50 / 5

a = 10 m/s².

Hence, the acceleration of the object will be 10 m/s².

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Answer:

F = 0 N

Explanation:

The problem does not talk about any acceleration. We can just assume it always moves at a constant speed so the resultant force will be 0 newtons. Of course you could say that it accelerates for a certain amount of time, as the wind blows, but the problem doesn't tell us when to calculate the resultant force (if during the acceleration or after) + we don't have the mass of the jet.

Answer:

Explanation:

Itz Deepika Here to help ~ .

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Answer:

hertz (Hz)

The number of periods or cycles per second is called frequency. The SI unit for frequency is the hertz (Hz).

Answer: the answer is hertz! if you’re on plato it’s option C. have a nice day! :)

Explanation:

In the endothermic reaction, the total energy of water and sodium chloride is greater than the total bond energy of hydrochloric acid and sodium hydroxide.

Endothermic reactions are reactions in which heat energy is absorbed during the reaction. The formation of products by the reactants requires addition of heat because the energy required to form the bond in the products is greater than the energy released when reactant bond are broken.

Thus, in an endothermic reaction, the total bond energy of the products are greater than the bond energy of the reactants.

The properties of endothermic reactions include:

Examples of endothermic reactions include;

The reaction between acids and bases to form salt and water known as neutralization reactions are usually exothermic in nature.

However, if a given reaction between hydrochloric acid and sodium hydroxide to produce water and sodium chloride is endothermic as in the question, the total energy of water and sodium chloride is greater than the total bond energy of hydrochloric acid and sodium hydroxide. ​

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Answer: C.) The total bond energy of water and sodium chloride is greater than the total bond energy of hydrochloric acid and sodium hydroxide.

Hope this helps :)