A child is stationary on a swing.(a)The child is given a push by his brother to start him swinging.His brother applies a steady force of 84 N over a distance of 0.25 m.(i) Calculate the work done by this force.(2)..............................................................................................................................................(ii) State how much energy is transferred by this force.(1)..............................................................................................................................................(iii) After several more pushes, the child has a kinetic energy of 71 J.The mass of the child is 27 kg.Show that the velocity of the child at this point is about 2.3 m/s.(2)(iv) Which one of these quantities changes in both size and direction while he is swinging?Put a cross ( ) in the box next to your answer.(1)Ahis gravitational potential energyBhis momentumCthe force of gravity acting on himDhis kinetic energy

Answers

Answer 1

Answer:

Work done = Fs

Explanation:

(i) W = Fxs

= 84N x0.25m

= 21 Joules

(ii) Ek = 1/2mv^2

71 = 1/2×27×v^2

71×2/27 = v^2

v = 23m/s

Answer 2

The work done by this force is 21 Joule.

Energy transferred by the force is 21 Joule.

The boy's momentum changes periodically, that is,  in both size and direction.

What is force?

An external force is an agent that has the ability to change the resting or moving condition of a body. It has a direction and a magnitude. So, it is  a vector quantity. Newton is the SI unit of force (N).

(i) Given parameter:

Steady force applied by his brother, F = 84 N.

Displacement, d = 0.25 m.

The work done by this force, W = F.d = 84×0.25 = 21 Joule.

(ii) Amount of work done is transferred by this force as an energy. So, amount of energy transferred by the force is 21 Joule.

(iii) Given parameter:

Mass of the child, m= 27 kg.

Kinetic energy, E = 71 J.

Let, velocity of the child = v, then kinetic energy is,

E = 1/2 × mv²

⇒ v = √(2E/m)

= √(2×71/27)

= 2.3 m/s.

Hence, the velocity of the boy is 2.3 m/s. (proved).

(iv) During swing, his velocity changes periodically. That's why, his momentum changes periodically, that is,  in both size and direction.

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negatively charged particles of radiation emitted from the decay of radioactive substances are known as

Answers

Answer: beta particles

Explanation:

that's the answer

plzz explain how it is 66 m
i know that distance =speed × time so how it is 66 m not a
0.4 and if there us another rule plz explain like if u day that 1/2 ×speed ×time plz explain why u used 1/2 or when do I use the 1/2 rule ​

Answers

Hi there!

For someone to hear an echo, the sound must echo and bounce back to the person.

Thus, the sound travels TWICE the distance from the person to the wall (to the wall and back).

We know that:

d = st  (distance = speed × time)

Let L = distance from person to wall

Thus:

2L = st

2L = 330 × 0.40

2L = 132

L = 66 m

the thermodynamic processes that occur in nature ____________.

Answers

Answer:

The thermodynamic processes that occur in nature convert thermal energy into mechanical energy.

The thermodynamic processes that occur in nature are according to the law of thermodynamics.

The thermodynamics processes seen in nature are guided by the law of thermodynamics. The role of energy and heat transmission in physical systems is guided by these laws.

The laws are:

(1) Energy cannot be created nor destroyed in a system, according to the first law of thermodynamics, Also, referred to as the law of energy conservation. Only from one form to another, the energy can be transmitted or altered. Energy is conserved through natural processes, keeping the overall amount constant.

(2) Second law of thermodynamics: states that the overall entropy of an isolated system tends to increase over time in any natural process. This suggests that processes progress towards a state of increasing disorder.

Hence, the thermodynamic processes are guided by the law of thermodynamics.

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As the temperature of an air mass increases, its atmospheric pressure______. Group of answer choices

Answers

Answer:

its atmospheric pressure decreases

When the temperature of an air mass increases, its atmospheric pressure drops

ok done. Thank to me :>

Image credit: The Hubble Heritage Team (AURASTSCI/NASA)
To which category does galaxy #2 belong? Why does it belong in this category?
WRITER

Answers

Can i ask u a question

how to do the next ques for more

Brainliest me please

Which of the following explains why NASA mandated that space food could NOT crumble or come apart?

Crumbs may cause electronics to malfunction.
There is no way to clean crumbs, so all food must be contained.
Floating crumbs may get into astronauts’ eyes.
Crumbs increase the risk of bacteria development.

Answers

Answer:

C.

Floating crumbs may get into astronauts’ eyes.

A swimming pool has dimension of 30m×10m×3m. When it is filled with water , what is the thrust on the bottom and sides

Answers

Answer:

3,900m³

Explanation:

what is rotational dynamics​

Answers

Answer:

Rotational dynamics is the study of forces and motions about an axis of rotation.

Explanation:

Formulas such as Kinematic Equations and Newton's laws can be expressed in rotating coordinate frames such as: Newton's 2nd Law Fnet=m x a translates into Torque = I x α Where I is Moment of Inertia (the rotational analogous term to mass)

Answer:

Rotational dynamics is the study of forces and motions about an axis of rotation.

Explanation:

Formulas such as Kinematic Equations and Newton's laws can be expressed in rotating coordinate frames such as:

Newton's 2nd Law Fnet=m x a translates into Torque =I x α Where I is Moment of Inertia (the rotational analogous term to mass)

and α is angular acceleration.

What are Newtons Laws famous for

Answers

Answer:

Why are Newton's laws of motion important? Newton's laws of motion are important because they are the foundation of classical mechanics, one of the main branches of physics. Mechanics is the study of how objects move or do not move when forces act upon them.

Because they are the foundations of classical mechanics

A ball is falling toward the ground. Which of the following statements are false? (a) The force that the ball exerts on Earth is equal in magnitude to the force that Earth exerts on the ball. (b) The ball undergoes the same acceleration as Earth. (c) The magnitude of the force the Earth exerts on the ball is greater than the mag- nitude of the force the ball exerts on the Earth.

Answers

Hi there!

(A) The force that the ball exerts on Earth is equal in magnitude to the force that Earth exerts on the ball.

Gravitational force is an example of an action-reaction pair:

[tex]F_{1,2} = -F_{2,1}[/tex]

Gravitational force is given by the equation:

[tex]F_g = \frac{Gm_1m_2}{r^2}[/tex]

Plugging in the masses of the Earth and ball, gravitational constant, and radius will result in the SAME GRAVITATIONAL FORCE exerted by both objects on each other.

Which factor is not a type of spectra?


A.


emission


B.


absorption


C.


continuous


D.


discontinuous

Answers

The correct answer is
D.) discontinuous

Brainliest?

why are some small jovian planet moons geologically active?

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Answer:

tidal heating and/or their composition  

Explanation:

The kinetic energy of an object can sometimes be greater than a potential energy a originally possessed, true or false?

Answers

Answer:

true

Explanation:

Energy stored in the nuclei of atoms can be used to generate electricity. ... Most of the energy of food is converted to heat.

I think it’s true because potential energy can be converted into kinetic energy so, the energy stored in the nuclei of atoms can be used to generate electricity. Ofc the kinetic energy will be greater than the potential energy !

The energy transferred per unit electric charge in a circuit is .
A current
B charge
C power
D potential difference​

Answers

Answer:

(D)

E = V Q      energy of charge Q  thus V = E / Q

what noncontact forces act on an object that are balanced

Answers

Answer:

I can give you a list of noncontact forces off of my head, if that is what you need.

Explanation:

First, gravity. It acts everywhere and pulls down every object that is in the air towards the ground, unless they have an equal and opposite force that counters it.

Second, wind. I don't think this will count because wind is a physical thing, but it can be used in the same way as we did with gravity. If the force counteracting it is larger, equal, and opposite of the force it is countering, then it will move forward, through the wind.

a box takes 350 N to start moving the coefficient of static friction is 0.35. what is the weight of the box?

Answers

Answer:

101.937 kg

Explanation:

The force needed to get the box moving must just cancel the static friction force:

F = µsmg  =  0.35•m•9.81 = 350 --->   m = 350 / (0.35•9.81) = 101.937 kg

Again, with units shown, and using 1 N = 1 kg•m/s2:

0.35•m•9.81(m/s2) = 350 N

solving for m:

m = 350 N / (0.35•9.81 m/s2)  =  (350 kg•m/s2) / (3.434 m/s2 ) = 101.937 kg

______________________

(Hope this helps can I pls have brainlist (crown)☺️

A car accelerates from 20m/s to 30m/s in 10 sec. Find the cars acceleration using v=u+at

Answers

Explanation:

we derive the formula of acceleration using the formula so v - u /t so

30-20/10

so the acceleration is 1 m/s square

Please find attached photograph for your answer.

Hope it helps.

Do comment if you have any query.

a trip from Austin to Dallas takes about 3 hours going 65 mi/hr north is this speed, velocity, or acceleration?

Answers

Answer:volocity

Explanation:

If the mass of the Earth is doubled, how will the moon’s orbit be affected?

Answers

What Would Happen to the Orbit of the Moon if it Were Twice as Massive? ... The orbit would not change.

HOPE IT HELPS:)

PLS FOLLOW:)

#BRAINLIEST:)

a device that converts mechanical energy into electricity is a

Answers

Answer:

An electric generator is a device that converts a form of energy into electricity.

Explanation:

A person who sits on the right-hand seat of the car that is making a left turn slides over to the right. What is the possible reason for this?

Answers

Answer:

zsjgbjidasngwhugbhwuabvhuvbwhuebewghvwev

Explanation:

11111111111111111111111111111111111111111111111111111

pls help me do these physic questions

Answers

Answer:

1 since it is meatl and sharp

2 since it is sharp and iron

....................................

Answers

Answer:

yeah

Explanation:

Helllo, hope you are doing well :)

a child has the kinetic energy of 71 j the mass of the child is 27kg show that the velocity of the child at this point is 2.3m/s

Answers

Explanation:

kinetic energy of child = 1/2 m v^2

71 j. = 1/2×27kg ×v^2

71×2/27= v^2

142/27 = v^2

5.3. =v^2

v= √5.3

v= 2.3 m/s

Determine the work done by the force Fx=(6x-4)N as the object moves from x1=0 to x2=3 m.

Answers

Answer:

15J

Explanation:

Let's assume force and motion have the same direction, so the dot product between the two reduces to the product of magnitudes.

If you studied calculus:  [tex]w= \int \limits^3_0 6x-4dx[/tex], by definition. Some "easy" math, that's [tex](3x^2-4x)\limits^3_0=27-12 - 0 = 15 J[/tex]

Else. we have to take the long way.  if the force was constant, and you plotted magnitude of the force vs position in a graph, you would get an horizontal line, and your work would be the area between the line and the x axis. And there is no reason why it shouldn't be the same for a variable force - if you think about it, it's the same way they justify the position formula for an accelerated motion. Let's graph it and start debating - sorry for my paint skills. We can easily say that in the green triangle the force is opposing the motion, so its work is negative, while in the blue area force and displacement go in the same direction, thus work is positive. Now it's just to calculate the area of two triangles

For the green one, it's a right triangle with side lengths 4 and 2/3, whose area is [tex]\frac12(4)(\frac23) = \frac43[/tex].

For the blue triangle, it's again a right triangle with side lengths 14 and 3-2/3= 7/3, whose area is [tex]\frac12(14)(\frac73) = \frac{49}3[/tex]

Our total work is the difference between the two, or [tex]w= \frac{49}3-\frac43 = \frac{45}3 = 15[/tex]

If two stars are in a binary system with a combined mass of 5.5 solar masses and an orbital period of 12 years, what is the average distance between the two stars

Answers

The average distance between the two stars is 792 light years

Let the mass of the first star be [tex]m_1[/tex]

Let the mass of the second star be [tex]m_2[/tex]

The combined mass of the two stars, [tex]m_1+m_2=5.5[/tex] solar masses

The orbital period of the stars, P = 12 years

Average distance between the two stars, D = ?

The average distance between the two stars can be calculated using Kepler's equation

[tex]D=(m_1+m_2)P^2[/tex]

Substitute [tex]m_1+m_2=5.5[/tex] and P = 12 into the formula [tex]D=(m_1+m_2)P^2[/tex]

[tex]D=5.5(12^2)[/tex]

D = 5.5(144)

D = 792 light years

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Describe the forces that make a bicycle move.

Answers

Answer:

this is an example of Newton's Second Law, acceleration happens when a force acts on a mass.

the force that makes the bicycle move is your foot pushing against the pedal

HELP PLZZZZZZ AHHHHH

Answers

Answer: I think it's larger

Explanation:  man im just trying to help you

Which one of the following is not a vector quantity? a) Displacement b ) density c) force d) vecocity​

Answers

Answer:

density

Explanation:

density is a scalar quantity having only magnitude and no info about derection

The acceleration of an object is inversely proportional to its mass, so if you decrease its mass while keeping the net force the same, the acceleration will increase.
true or false​

Answers

Answer:

True

Explanation:

Since acceleration is inversely proportional to mass, decreasing mass will make the object lighter, and thus easier to speed up. So acceleration increases as mass decreases and vice versa

Answer: TRUE                                                                        Explanation:Newton's second law of motion can be formally stated as follows: The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.

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