The kinetic energy of a javelin is 81 J, and its speed is 9.0 m/s. What is its mass?

A. 0.5 kg

В. 1.0 kg

C. 2.0 kg

D 9.0 kg

help asap

Answers

Answer 1

Explanation:

[tex]kinetic \: energy = \frac{1}{2} m {v}^{2} [/tex]

[tex]81 = \frac{1}{2}m {(9)}^{2} [/tex]

[tex] \frac{81 \times 2}{81} = m[/tex]

[tex]m = 2kg[/tex]


Related Questions

Scientists have organized all forms of energy into two types—kinetic and potential. Kinetic energy is the energy of motion, and potential energy is stored energy.

Raise the pendulum again. Carefully watch the Energy Graph on the left. It shows the amount of energy the pendulum has as it moves.

At the top of its swing, does the pendulum have kinetic energy or potential energy?
PLEASE HELP!

Answers

Answer:

Potential energy only

Explanation:

at the top of its swing the pendulum stops moving , (therefore it has no KINETIC energy)  thus all of the energy is stored as potential energy.

What does a 'dead' battery mean chemically? a) q > 1 b) q < 1 c) q = 1 d) q = k e) q/k = 0

Answers

Answer:

d) q=k

Explanation:

When a battery is "dead" it means that the chemical components are at equilibrium. When that occurs,

Δ

G

= 0, and Q = K.

A 'dead' battery mean chemically Q=1. At this position, the battery is at equilibrium condition, and considered as dead.

What is dead battery?

Dead battery is the battery in which no flow of electron take place as there is no potential difference.

Chemically, the battery is considered as dead battery, when there is no chemical process happens in battery.

Q is a reaction quotient of Nernst Equation for a battery.At the equilibrium condition, the value of Q is to become equal to 1. At this condition, the battery is considered as dead.

Thus, a 'dead' battery mean chemically Q=1. At this position, the battery is at equilibrium condition, and considered as dead.

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Which is NOT a characteristic of
the temperate region?
A. a lot of organic matter
B. moderate temperatures
C. moderate rainfall
D. under-developed soil horizons

Answers

Answer:

under developed soil horizons

What is the definition of the word PER?

Answers

Answer:

Per is a Latin preposition that means "through" or "by means of". Per (pronounced like "purr") is also an English preposition that can mean "for each", "to each", "by means of", or [lastly, annoyingly] "in accordance with"; somewhat interchangeably with the [even more annoying] "as per". In the example expressions here, it conveys "because of the rationale presented at/by".

Answer:

(Entry 1 of 4) 1 : by the means or agency of : through per bearer. 2 : with respect to every member of a specified group : for each. 3 : according to —often used with as per instructionsas per usual.

Explanation:

A body of mass 0.1 kg falling freely under gravity takes 10 s to reach the ground. Calculate the kinetic energy and potential energy of the body when it has travelled for first 6 s. Given, g = 9.8 m/ s²​

Answers

Answer: KE = 172.872 J

PE = 307.328 J

Explanation:

For KE: acceleration = change in velocity / time → 9.8 = final velocity - 0 (because initial velocity is zero) / 6s → final velocity after 6s = 58.8 m/s.

Now, plug this into: KE = 1/2(m)(v^2) → KE = 1/2(.1)(58.8^2) = 172.872 J.

For PE: Find the velocity after 10 s: acceleration = change in velocity / time → 9.8 = final velocity - 0 (because initial velocity is zero) / 10s → final velocity after 10s = 98 m/s.

Now, find the total height: (v final)^2 = (v initial)^2 + 2*a*d → 98^2 = 0^2 + 2*9.8*d → d = total height = 490 m.

Now, find the change in height after 6 s: (v final)^2 = (v initial)^2 + 2*a*d → 58.8^2 = 0^2 + 2*9.8*d → d = change in height after 6 s → 176.4 m

Now, subtract the change in height from the total height to get its height after 6s: 490-176.4=313.6m

PE = m*g*h → Pe=.1*9.8*313.6 = 307.328 J :)

Both Transverse and Longitudinal Waves transmit____and not_____

A power, work

B work, power

C energy, matter

D matter, energy​

Answers

Explanation:

How are animals similar? All animals are made of many cells. Most animals can move on their own. Like all living things, animals grow, change, reproduce, and respond to their environment.

Which is the surest test of charge on a body?
(a) Repulsion
(b) Lightning
(c) Combustion
(d) Insulation

Answers

Answer:

Repulsion

Explanation:

Unlike attraction of magnets opposite polls

Repulsion happens between same polesLike if you put north pole to north poll they get repulsed .Same with south poles

Answer:

Repulsion

Explanation:

Brainliest MisterBrainly

[tex]\red{ \rule{0pt}{900000pt}}[/tex]

1. Why don't you see your reflection in a building made of rough, white stone?

Answers

the light that hits the surface of it is scattered.

if i were to (HYPOTHETICALLY) punt a small child off of a building, (HYPOTHETICALLY) how long would it take for the (VERY HYPOTHETICAL) child to reach maximum velocity?
(HYPOTHETICALLY) the child would weigh 88 pounds, have blond hair and blue eyes, and (HYPOTHETICALLY) be named "Jacob."

THIS QUESTION IS HYPOTHETICAL AND I AM TOTALLY NOT PLANNING TO COMMIT AN ATROCITY!

Answers

Answer:

Around 190-ish miles per hour when it hit the ground maybe

Explanation:

Which image corresponds to what moment in time? (1 point) The low-pitched sound corresponds to the sound source getting closer, its wavelength is longer. The high-pitched sound corresponds to the sound source moving away, its wavelength is shorter. The low-pitched sound corresponds to the sound source moving away; its wavelength is shorter. The high-pitched sound corresponds to the sound source getting closer; its wavelength is longer. The low-pitched sound corresponds to the sound source getting closer, its wavelength is shorter. The high-pitched sound corresponds to the sound source moving away, its wavelength is longer. The low-pitched sound corresponds to the sound source moving away, its wavelength is longer. The high-pitched sound corresponds to the sound source getting closer, its wavelength is shorter.​

Answers

Answer:

The low-pitched sound corresponds to the sound source moving away; its wavelength is longer. The high-pitched sound corresponds to the sound source getting closer; its wavelength is shorter.

Just took the quiz, and it said this answer was correct.

In this picture, The low-pitched sound corresponds to the sound source moving away; its wavelength is longer. The high-pitched sound corresponds to the sound source getting closer; its wavelength is shorter.

What is wave ?

Wave is is a disturbance in a medium that carries energy as well as momentum . wave is characterized by amplitude, wavelength and phase. Amplitude is the greatest distance that the particles are vibrating. especially a sound or radio wave, moves up and down. Amplitude is a measure of loudness of a sound wave. More amplitude means more loud is the sound wave.

Wavelength is the distance between two points on the wave which are in same phase. Phase is the position of a wave at a point at time t on a waveform.

There are two types of the wave longitudinal wave and transverse wave.

Longitudinal wave : in which, vibration of the medium (particle) is parallel to propagation of the wave. Sound wave is a longitudinal wave.

Transverse wave : in which, vibration of the medium (particle) is perpendicular to propagation of the wave. Light wave is a Transverse wave.

According to the Doppler's effect, a sound source moves away from the observer its wavelength increases and when it moves towards the observer the wavelength decreases.  

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What kind of model is this?
A. Experimental model
O B. Mathematical model
O C. Computer model
o
D. Physical model

Answers

Answer:

I think it's Experimental

Explanation:

it has atoms on it.

Answer:

D

Explanation:

It is a physical model.

Daryl uses a microphone connected to an oscilloscope to study sound waves. He finds that higher pitched sounds have higher frequencies and shorter wavelengths while lower pitched sounds have lower frequencies and longer wavelengths. Daryl concludes that the relationship between the frequency and the wavelength of sound waves in air is the result of causation and not correlation. In two to three sentences, describe whether Daryl’s conclusion is correct and explain why or why not.

Answers

Daryl’s conclusion that the relationship between the frequency and the wavelength of sound waves in air is the result of causation is correct.

What is Causation?

This is defined as the relationship between successive events when the first event brings about the other.

The higher frequencies brings about shorter wavelengths which is why it is termed as being  a result of causation.

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A proton wit a kinetic energy of 9. 3 x 10^-15 j moves perpendicular to a magnetic field of 0. 87 t. What is the radius of its circular path?

Answers

The radius of the given circular path moved by the proton which is perpendicular to a magnetic field of 0.87 T determined as 4 cm.

Magnetic force of the proton

The magnitude of the magnetic force on the proton is determined using the following formula;

F = qvBsin(θ)

Centripetal force on the proton

The centripetal force of the circular path is given as;

F = mv²/r

Solve the two equations together,

[tex]\frac{mv^2}{r} = qvBsin(90)\\\\r = \frac{mv}{qB}[/tex]

Where;

v is the speed of the protonSpeed of the proton

The speed of the proton is determined from its kinetic energy;

[tex]K.E = \frac{1}{2}mv^2\\\\ v= \sqrt{\frac{2K.E}{m} } \\\\v = \sqrt{\frac{2 \times 9.3 \times 10^{-15}}{1.67 \times 10^{-27}} } \\\\v = 3.33\times 10^6 \ m/s[/tex]

Radius of the circular path

The radius of the circular path is calculated as follows;

[tex]r = \frac{(1.67 \times 10^{-27}) \times (3.33 \times 10^6)}{(1.6\times 10^{-19}) \times (0.87)} \\\\r = 0.04\ m\\\\r = 4 \ cm[/tex]

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A book on a shelf 2.5 m above the floor has a mass of 1.7 kg. What is the gravitational potential energy of the book?

Answers

Answer:

42.5J (If g = 10)

41.6925J (If g = 9.81)

41.67975J (If g = 9.807)

Explanation:

Gravitational Potential Energy = Mass X Height X Gravitaitonal Field

Earth's Gravity is = 9.807 m/s^2

It is often rounded to 9.81 or 10

Use F = 1/T as your basis:
9. Find the frequency of a tuning fork that takes 2.50×10−3s to complete one oscillation.

The answer is 400 Hz but please show your work.

Answers

Time Period=T=2.5×10^{-3}s

Now

Frequency:-

[tex]\\ \rm\rightarrowtail \nu=\dfrac{1}{T}[/tex]

[tex]\\ \rm\rightarrowtail \nu=\dfrac{1}{2.5\times 10^{-3}}[/tex]

[tex]\\ \rm\rightarrowtail \nu=0.4\times 10^{3}[/tex]

[tex]\\ \rm\rightarrowtail \nu=400Hz[/tex]

The frequency for this time will be 400 Hz.

What is the frequency?

Frequency is defined as the ratio of the number of waves to time. It is denoted by f.

f=[tex]\frac{1}{T}[/tex] where,

f is the frequency and,

T is the time period.

SI unit of frequency is Hz.

There are different types of frequency in sound :

Infrasonic-The frequency is less than 20 Hz.Audible-The frequency is between 20Hz to 20,000 Hz.Ultrasonic-The frequency is greater than 20,000 Hz.

According to the question :

Given :

T= 2.50×[tex]10^{-3}[/tex]

f=[tex]\frac{1}{T}[/tex]

⇒f=1/(2.50×[tex]10^{-3}[/tex])

⇒400 Hz

Hence, the frequency for this time will be 400 Hz.

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A rock with a 8 kg mass is tied to a string and swung in a circular path. The 1.8 meter string is tied to a post, and during the motion, the string has a 35° angle with the post. The rock makes 100 rounds in 3 minute. The centripetal force on the ball is __ N.

Answers

The centripetal force of the rock tied to a string and swung in a circular path is determined as 1.65 N.

Angular speed of the rock

The angular speed of the rock is calculated as follows;

ω = 2π N

[tex]\omega = 35^0 \times \frac{2 \pi \ rad}{360^0} \times \frac{100}{3\min} \times \frac{1 \min}{60 \ s} \\\\\omega = 0.339 \ rad/s[/tex]

Centripetal force of the rock

The centripetal force of the rock is calculated from the product of mass and centripetal acceleration as shown below;

Fc = ma

Fc = m(ω²r)

Fc = mω²r

Fc = 8 x (0.339)² x 1.8

Fc = 1.65 N

Thus, the centripetal force of the rock tied to a string and swung in a circular path is determined as 1.65 N.

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A dense mix of dry, hot rock fragments and hot gas erupting from volcanic vents at high speed is pyroclastic flow. lahar. fumarole. tephra.

Answers

The answer is pyroclastic

Magma is called for the dense mix of dry hot rock fragments and hot gas erupting from volcanic vent at high speed.

What is magma?

Magma is the extremely hot liquid and flows under the surface of the earth. When this liquid comes out to the surface of earth, then called as lava.

Gas bubble, making up to lave are energetic in nature, because they keep on expanding in all directions, they will go all out to the only open are of a volcano, the vent, in an upward direction.

Hence Magma is called for the dense mix of dry hot rock fragments and hot gas erupting from volcanic vent at high speed.

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The top speed of a car is determined by several factors including:

*Power of the motor
*Weight of the car
*Aerodynamics of the car
*Grip of the tires on the road

1) How would you go about determining which of these has the strongest effect?

Helppp!!

Answers

Answer:

Power of the motor.

Explanation:

If it didn't have grip, it would still move. If it was barely aerodynamic (pretty sure nothing can be not aerodynamic at all) it would still move. If it weighed more that the sun (and you had a strong enough motor) it would still move but without a motor, it won't move. Therefore, the motor is the most effective.

a wind turbine is an example of what kind of device
a. a generator
b. a transformer
c. a motor
d. an electromagnet

Answers

Answer:

it’s an example of a generator.

Explanation:

Answer:

Generator

Explanation:

valid

the earth exerts a gravitational force of 850N on John. What is Johns mass in kg

Answers

Answer:

86.73 kg

Explanation:

Remember that F=mg

Let's plugin our numbers

850N=m9.8m/s^2

850N=9.8m/s^2m

86.73=m

Two objects of the same mass travel in the same direction along a horizontal surface. Object X
has a speed of 5 ms
and object Y
has a speed of 2 ms
, as shown in the figure. After a period of time, object X
collides with object Y
.

Consider the situation in which the objects collide but do not stick together. Which of the following predictions is true about the center of mass of the two-object system immediately after the collision?

Answers

After the collision, object X will move at a speed of 2 m/s in its original direction while object Y will move at a speed of 5 m/s in its original direction.

Elastic collision of the two objects

When the two objects collide but do not stick together, the type of collision is elastic collision.

In elastic collision, both momentum and kinetic energy are conserved.

Final velocity of the two objects after collsion

mu₁ + mu₂ = mv₁ + mv₂

5m + 2m = mv₁ + mv₂

m(5 + 2) = m(v₁ + v₂)

7 = v₁ + v₂ -------- (1)

Apply the concept of one direction velocity;

u₁ + v₁ = u₂ + v₂

5 + v₁ = 2 + v₂

v₂ = v₁ + 3 ------ (2)

Solve (1) and (2) together;

7 = v₁ + v₁ + 3

4 = 2v₁

v₁  = 2 m/s

v₂  = 2 + 3 = 5 m/s

Thus, after the collision, object X will move at a speed of 2 m/s in its original direction while object Y will move at a speed of 5 m/s in its original direction.

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A thin uniform disk of mass m and radius r has a string wrapped

Answers

The magnitude of the weight of the disk is greater than the magnitude of the tension force of the string. ((c) [tex]F_{T} < F_{g}[/tex])

How to analysis a rigid body on dynamical condition

A rigid body is a system whose geometry cannot be neglected and in which deformations due to external forces applied on the system are negligible.

In this question we need to establish a free body diagram with all critical forces and motion conditions. There are two external forces: (i) tension ([tex]F_{T}[/tex]), (ii) weight ([tex]F_{g}[/tex]), both in newtons.

The disk falls due to gravity and rotates around the string in a case of rolling, which combines rotation and translation. By Newton's laws of motion we have the following expression:

[tex]\sum F = -F_{g}+F_{T} = -m\cdot R\cdot \alpha[/tex]   (1)

Where:

[tex]m[/tex] - Mass of the disk, in kilograms.[tex]\alpha[/tex] - Angular acceleration, in radians per square second.

By algebra we derive the following relationship between the two forces:

[tex]-F_{g} = -F_{T}-m\cdot R\cdot \alpha[/tex]

[tex]F_{g} > F_{T}[/tex]

Therefore, the magnitude of the weight of the disk is greater than the magnitude of the tension force of the string. ((c) [tex]F_{T} < F_{g}[/tex]) [tex]\blacksquare[/tex]

Remark

The statement is incomplete and poorly formatted. Correct and complete form is shown below:

A thin uniform disk of mass m and radius r has a string wrapped around its edge and attached to the ceiling. The bottom of the disk is at height 3R above the floor, as shown above. The disk is released from rest. The rotational inertia of a disk around its center is [tex]I = \frac{1}{2}\cdot M\cdot R^{2}[/tex].

When released from rest, the disk falls and the string unwinds. The force that the string exerts on the disk is [tex]F_{T}[/tex], and the gravitational force exerted on the disk is [tex]F_{g}[/tex]. Which of the following expression correctly relates [tex]F_{T}[/tex] and [tex]F_{g}[/tex] as the disk falls?

(a) [tex]F_{T} > F_{g}[/tex], (b) [tex]F_{T} = F_{g}[/tex], (c) [tex]F_{T} < F_{g}[/tex]

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A car is traveling in a race. The car went from the initial velocity of 35 m/s to the final velocity of 65 m/s in 5 seconds
What is the acceleration?
- 13 m/s
-6m/s
6 m/s
13 m/s

Answers

Answer:

C

Explanation:

65-35 = 30

30 divided by 5 = 6

The answer will be 6 m/s

Explanation:

c............ ......

...

If a 2.00 kg ball is thrown straight up world and its maximum height is 25.51 m. Approximately how much potential energy (PE) dose the ball possess when it reaches it’s maximum height (g=9.8 m/s^2)

Answers

Answer:

500

Explanation:

im not sure if this is right but if its not im very sorry and i hope you have a great day or night wherever you are

write comparison between Electrical Circuit and Magnetic Circuit.

[tex] \\ \\ \\ \\ \\ \\ \\ [/tex]


Thanks¡!¡:)​

Answers

Magnetic circuit, closed path to which a magnetic field, represented as lines of magnetic flux, is confined.

In contrast to an electric circuit through which electric charge flows, nothing actually flows in a magnetic circuit.

Explanation:

Hope it helps you (`▿▿▿▿´ƪ)

How to know if two vectors are linearly independent

Answers

Answer:

Given a set of vectors, you can determine if they are linearly independent by writing the vectors as the columns of the matrix A, and solving Ax = 0.

Explanation:

You may verify if a group of vectors is linearly independent by expressing the vectors as columns of the matrix A and solving Ax = 0.

What is a vector?

A vector is a quantity or phenomena with magnitude and direction that are independent of one another. The phrase also refers to a quantity's mathematical or geometrical representation.

If no vector can be written as a linear combination of the others, a set of vectors is said to be linearly independent.

If no vector in a collection of vectors can be written as a linear combination of the ones mentioned before it, the set is said to be linearly independent.

A nontrivial linear combination yields the zero vector, the vectors are said to be dependent.

You may verify if a group of vectors is linearly independent by expressing the vectors as columns of the matrix A and solving Ax = 0.

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An electromagnetic radio wave is received by a transmitter before it is converted to a sound wave. The radio wave has a wavelength of 23,076 m and a frequency of 13,000 Hz. What velocity is the wave traveling at before the transmitter converts it to a sound wave? 1. 76 m/s 0. 56 m/s 3. 31 × 102 m/s 3. 00 × 108 m/s.

Answers

The velocity the wave was traveling at before the transmitter converts it to a sound wave is 3.0 x 10⁸ m/s.

What is Velocity of waves?

The velocity of waves is the rate of change of the wave's displacement with time.

The velocity of waves is determined by taking the product of the wave's frequency and wavelength.

v = fλ

v = 13,000 x 23,076

v = 3.0 x 10⁸ m/s.

Thus, the velocity the wave was traveling at before the transmitter converts it to a sound wave is 3.0 x 10⁸ m/s.

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Suppose that a simple pendulum consists of a small 60.0 g bob at the end of a cord of negligible mass. If the angle 0 between the cord and the vertical is given by g - (0.0800 rad) cos[(4.43 rad/s) t 0], what are (u) the pendulum's length and (b) its maximum kinetic energy

Answers

Based on the mass of the bob and the angle between the cord and the vertical, the pendulum length is 0.50m.

The maximum kinetic energy can be found to be 9.42 x 10⁻⁴J.

What is the pendulum length?

This can be found as:

= g-force / w²

Solving gives:

= 9.8 / 4.43²

= 0.4998 m

= 0.50 m

What is the maximum kinetic energy?

This can be found as:

= 0.5 × m × w² × A²

Maximum kinetic energy is:

= 0.5 × 60 × 10⁻³ × (4.43 × 0.4998 x 0.08 rad)²

= 9.42 x 10⁻⁴J

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more than one option this is hard

Answers

You have to select all of them bcz all of them are right

How do scientists know that seafloor spreading occurs?Explain how this spreading causes the continents to seperate.

Answers

second question: tensional stress causes fractures to occur in the lithosphere.
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