PLEASE HELP ME WITH THIS ONE QUESTION
What is the rest energy of a proton? (c = 2.9979 x 10^9 m/s, mp = 1.6726 x 10^-27)

Answer:

Approximately 4.029 A

Explanation:

We can use the formula that the B field of a few loops all with current in same direction is permeability of free space (mu)* current * Number or loops divided by 2*radius. You are given B field, radius(convert into meters), number of loops and mu is 4pi * 10^-7. Solve for current and you get 4.029 Amperes.

Answer:

m = 0.057 kg = 57 g

Explanation:

Energy Added to Water = Heat added to raise the temperature of water + Heat used to vaporize water

[tex]E = mC\Delta T + mH\\E = m(C\Delta T + H)[/tex]

where,

E = Energy added to water = 145 KJ

m = mass of water = ?

C = specific heat capacity of water = 4.2 KJ/kg.°C

ΔT = change in temperature = 100°C - 35°C = 65°C

H = Latent heat of vaporization of water = 2260 KJ/kg

Therefore,

[tex]145\ KJ = m[(4.2\ KJ/kg.^oC)(65^oC)+2260\ KJ/kg]\\\\145\ KJ = m(2533\ KJ/kg)\\\\m = \frac{145\ KJ}{2533\ KJ/kg}[/tex]

m = 0.057 kg = 57 g

The mass of water that can be heated is equal to 0.527 kilograms.

Given the following data:

Scientific data:

To calculate the mass of water that can be heated:

Note: The quantity of energy added to water is equal to the quantity of heat used to vaporize water and the quantity of heat that is added to raise the temperature of water.

Mathematically, this is given by this expression:

[tex]E=mc\theta + mH\\\\E= m(c\theta + H)[/tex]

Making m the subject of formula, we have:

[tex]m=\frac{E}{c\theta + H}[/tex]

Substituting the parameters into the formula, we have;

[tex]m=\frac{145000}{[42000\times (100-35)] + 2260}\\\\m=\frac{145000}{(4200\times 65) + 2260}\\\\m=\frac{145000}{273000 + 2260}\\\\m=\frac{145000}{275260}[/tex]

Mass, m = 0.527 kilograms.

Read more on quantity of energy here: https://brainly.com/question/13439286

Answer:

4 s

Explanation:

We are asked to calculate time taken (t).

By using the first equation of motion,

[tex]\longrightarrow[/tex] v = u + at

[tex]\longrightarrow[/tex] 160 = 100 + 15t

[tex]\longrightarrow[/tex] 160 - 100 = 15t

[tex]\longrightarrow[/tex] 60 = 15t

[tex]\longrightarrow[/tex] 60 ÷ 15 = t

[tex]\longrightarrow[/tex] 4 s = t

(a) Let x be the maximum elongation of the spring. At this point, the glider would have zero velocity and thus zero kinetic energy. The total work W done by the spring on the glider to get it from the given point (4.00 cm from equilibrium) to x is

W = - (1/2 kx ² - 1/2 k (0.0400 m)²)

(note that x > 4.00 cm, and the restoring force of the spring opposes its elongation, so the total work is negative)

By the work-energy theorem, the total work is equal to the change in the glider's kinetic energy as it moves from 4.00 cm from equilibrium to x, so

W = ∆K = 0 - 1/2 m (0.835 m/s)²

Solve for x :

- (1/2 (160 N/m) x ² - 1/2 (160 N/m) (0.0400 m)²) = -1/2 (0.190 kg) (0.835 m/s)²

==>   x ≈ 0.0493 m ≈ 4.93 cm

(b) The glider attains its maximum speed at the equilibrium point. The work done by the spring as it is stretched away from equilibrium to the 4.00 cm position is

W = - 1/2 k (0.0400 m)²

If v is the glider's maximum speed, then by the work-energy theorem,

W = ∆K = 1/2 m (0.835 m/s)² - 1/2 mv ²

Solve for v :

- 1/2 (160 N/m) (0.0400 m)² = 1/2 (0.190 kg) (0.835 m/s)² - 1/2 (0.190 kg) v ²

==>   v ≈ 1.43 m/s

(c) The angular frequency of the glider's oscillation is

√(k/m) = √((160 N/m) / (0.190 kg)) ≈ 29.0 Hz

The amplitude of the motion is 0.049 cm. The maximum speed of the glider is 1.429 m/s. The angular frequency of the oscillation is 29.02 rad/s

From the given information;

Using energy conservation E, the amplitude of the motion can be calculated by using the formula:

[tex]\mathbf{E = \dfrac{1}{2}mv^2 + \dfrac{1}{2}kx^2}[/tex]

[tex]\mathbf{E = \dfrac{1}{2}(0.19 \ kg )\times (0.835)^2 + \dfrac{1}{2}(160) (0.04)^2}[/tex]

[tex]\mathbf{E =0.194 \ J}[/tex]

Similarly, we know that:

[tex]\mathbf{E = \dfrac{1}{2}kA^2}[/tex]

Making amplitude A the subject, we have:

[tex]\mathbf{A = \sqrt{\dfrac{2E}{k}}}[/tex]

[tex]\mathbf{A = \sqrt{\dfrac{2(0.194)}{160}}}[/tex]

[tex]\mathbf{A =0.049 \ cm}[/tex]

Again, using the energy conservation, the maximum speed of the glider can be calculated by using the formula:

[tex]\mathbf{E =\dfrac{1}{2} mv^2 _{max}}[/tex]

[tex]\mathbf{v _{max} = \sqrt{\dfrac{2E}{m}}}[/tex]

[tex]\mathbf{v _{max} = \sqrt{\dfrac{2\times 0.194}{0.19}}}[/tex]

[tex]\mathbf{v _{max} = 1.429 \ m/s}[/tex]

The angular frequency of the oscillation can be computed by using the expression:

[tex]\mathbf{\omega = \sqrt{\dfrac{k}{m}}}[/tex]

[tex]\mathbf{\omega = \sqrt{\dfrac{160}{0.19}}}[/tex]

ω = 29.02 rad/s

Learn more about energy conservation here:

https://brainly.com/question/13010190?referrer=searchResults

Answer:

219 ft

Explanation:

Here we can define the value t = 0s as the moment when the car starts decelerating.

At this point, the acceleration of the car is given by the equation:

A(t) = -10 ft/s^2

Where the negative sign is because the car is decelerating.

To get the velocity equation of the car, we integrate over time, to get:

V(t) = (-10 ft/s^2)*t + V0

Where V0 is the initial velocity of the car, we know that this is 88 ft/s

Then the velocity equation is:

V(t) = (-10 ft/s^2)*t + 88ft/s

To get the position equation we need to integrate again, this time we get:

P(t) = (1/2)*(-10 ft/s^2)*t^2 + (88ft/s)*t + P0

Where P0 is the initial position of the car, we do not know this, but it does not matter for now.

We want to find the total distance that the car traveled in a 3 seconds interval.

This will be equal to the difference in the position at t = 3s and the position at t = 0s

distance = P(3s) - P(0s)

 = ( (1/2)*(-10 ft/s^2)*(3s)^2+ (88ft/s)*3s + P0) - ( (1/2)*(-10 ft/s^2)*(0s)^2 + (88ft/s)*0s + P0)

=  ( (1/2)*(-10 ft/s^2)*9s^2+ (88ft/s)*3s + P0) - ( P0)

=  (1/2)*(-10 ft/s^2)*9s^2+ (88ft/s)*3s = 219ft

The car advanced a distance of 219 ft in the 3 seconds interval.

Answer:

All the given options will result in an induced emf in the loop.

Explanation:

The induced emf in a conductor is directly proportional to the rate of change of flux.

[tex]emf = -\frac{d \phi}{dt} \\\\where;\\\\\phi \ is \ magnetic \ flux\\\\\phi = BA\ cos \theta[/tex]

where;

A is the area of the loop

B is the strength of the magnetic field

θ is the angle between the loop and the magnetic field

Considering option A, moving the loop outside the magnetic field will change the strength of the magnetic field and consequently result in an induced emf.

Considering option B, a change in diameter of the loop, will cause a change in the magnetic flux and in turn result in an induced emf.

Option C has a similar effect with option A, thus both will result in an induced emf.

Finally, considering option D, spinning the loop such that its axis does not consistently line up with the magnetic field direction will change the angle between the loop and the magnetic field. This effect will also result in an induced emf.

Therefore, all the given options will result in an induced emf in the loop.

Answer:

W =  343.2 J

Explanation:

Given that,

Mass of bale of hay = 26 kg

Horizontal force exerted = 88 N

Distance moved, d = 3.9 m

Work done, W = Fd

Put all the values,

W = 88 N × 3.9 m

= 343.2 J

So, the work done is 343.2 J.  

Answer:

a) Initial Temperature = 609.4 K and Final Temperature = 325.7 K

b) the change in internal energy is -18279.78 J

c) heat lost by the gas is zero or 0

d) the work done on the gas is -18279.78 J

Explanation:

Given the data in the question;

P[tex]_i[/tex] = 1 atm = 101325 pascal

P[tex]_f[/tex] = ?

V[tex]_i[/tex] = 0.1550 m³

V[tex]_f[/tex] = 0.742 m³

we know that for an adiabatic process  γ = 1.4

P[tex]_i[/tex]V[tex]_i^Y[/tex] = P[tex]_f[/tex]V[tex]_f^Y[/tex]

P[tex]_f[/tex] = P[tex]_i[/tex][tex]([/tex] V[tex]_i[/tex] / V[tex]_f[/tex] [tex])^Y[/tex]

we substitute

P[tex]_f[/tex] = 1 × [tex]([/tex] 0.1550  / 0.742  [tex])^{1.4[/tex]

= [tex]([/tex] 0.2088948787 [tex])^{1.4[/tex]

= 0.11166 atm

a) the initial and final temperatures

Initial temperature

T[tex]_i[/tex] = P[tex]_i[/tex]V[tex]_i[/tex] / nR

given that n = 3.10 mol

= ( 101325 × 0.1550 ) / ( 3.10 × 8.314 )

= 15705.375 / 25.7734

T[tex]_i[/tex]  = 609.4 K

Final temperature

T[tex]_f[/tex] = P[tex]_f[/tex]V[tex]_f[/tex] / nR

= ( 0.11166 × 101325 × 0.742 ) / ( 3.10 × 8.314 )

= 8394.95 / 25.7734

= 325.7 K

Therefore, Initial Temperature = 609.4 K and Final Temperature = 325.7 K

b) the change in internal energy

ΔE[tex]_{int[/tex] = nC[tex]_v[/tex]ΔT

here, C[tex]_v[/tex] = ( 5/2 )R

ΔE[tex]_{int[/tex] = 3.10 × ( 5/2 )8.314 × ( 325.7 - 609.4 )

= -18279.78 J

Therefore, the change in internal energy is -18279.78 J

c) the heat lost by the gas

Since its an adiabatic process,

Q = 0

Therefore, heat lost by the gas is zero or 0

d)  the work done on the gas

W = ΔE[tex]_{int[/tex] - Q

= -18279.78 J - 0

W = -18279.78 J

Therefore, the work done on the gas is -18279.78 J

a) The Initial Temperature and Final Temperature of gas are 601.68 K and 321.61 K respectively.

b) The change in internal energy is -18279.78 J.

c) The heat lost by the gas is zero.

d) The work done on the gas is -18279.78 J.

Given data:

The moles of sample is, n = 3.10 mol.

The initial volume of sample is, [tex]V_{1}=0.1550 \;\rm m^{3}[/tex].

The final volume of sample is, [tex]V_{2}=0.742 \;\rm m^{3}[/tex].

The initial pressure of the sample is, [tex]P_{1}=1.00 \;\rm atm[/tex].

(a)

We know that the relation between the pressure and volume for an adiabatic process is as follows,

[tex]P_{1}V_{1}^{\gamma} = P_{2}V_{2}^{\gamma}[/tex]

Here, [tex]\gamma[/tex]  is a adiabatic index. And for air, its value is 1.41.

Solving as,

[tex]P_{2}=P_{1} \times\dfrac{V_{1}^{\gamma}}{V_{2}^{\gamma}}\\\\\\P_{2}=1.00 \times\dfrac{0.1550^{1.41}}{0.742^{1.41}}\\\\\\P_{2} = 0.11166 \;\rm atm[/tex]

Now, calculate the final temperature using the ideal gas equation as,

[tex]P_{2}V_{2}=nRT_{2}\\\\T_{2}= \dfrac{P_{2} \times V_{2}}{nR}\\\\T_{2}= \dfrac{0.11166 \times 10^{5}\times 0.742}{3.10 \times 8.31}\\\\T_{2}=321.61 \;\rm K[/tex]

Similarly, calculate the initial temperature as,

[tex]P_{1}V_{1}=nRT_{1}\\\\T_{1}= \dfrac{P_{1} \times V_{1}}{nR}\\\\T_{1}= \dfrac{1 \times 10^{5}\times 0.1550}{3.10 \times 8.31}\\\\T_{1}=601.68 \;\rm K[/tex]

Thus, we can conclude that the initial and final temperature of the gas is 601.68 K and 321.61 K respectively.

(b)

The change in internal energy is given as,

ΔE = nCΔT

here, C = ( 5/2 )R

ΔE = 3.10 × ( 5/2 )8.314 × ( 325.7 - 609.4 )

      = -18279.78 J

Therefore, the change in internal energy is -18279.78 J.

c)

The heat lost by the gas . Since its an adiabatic process, so there will be no heat interaction.  

Q = 0

Therefore, heat lost by the gas is zero or 0

d)  

The work done on the gas

W = ΔE - Q

W = -18279.78 J - 0

W = -18279.78 J

Therefore, the work done on the gas is -18279.78 J.

Learn more about the adiabatic process here:

https://brainly.com/question/14930930

Answer:

0.3 N

Explanation:

Electromagnetic force is F= Kq1q2/r^2, where r is the distance between charges. If r is doubled then the force will be 1/4F which is 0.3 N.

The magnitude of the force exerted on Q by q when the distance between them is doubled is 0.3 N

F = Kq₁q₂ / r²

Where

From Coulomb's law,

F = Kq₁q₂ / r²

Cross multiply

Fr² = Kq₁q₂

Kq₁q₂ = constant

F₁r₁² = F₂r₂²

With the above formula, we can obtain the final force as follow:

F₁r₁² = F₂r₂²

1.2 × r² = F₂ × (2r)²

1.2r² = F₂ × 4r²

Divide both side by 4r²

F₂ = 1.2r² / 4r²

F₂ = 0.3 N

Learn more about Coulomb's law:

https://brainly.com/question/506926

Answer:

Soft iron

Explanation:

Answer:

1. CaO is not an organic compound because it doesn’t contain a carbon molecule.

2.

Name General Structure Properties/Uses

Alcohol R-OH (contains a hydroxyl group)  Can be poisonous, can be made from fermentation or distillation

Aldehyde R-COH (contains a carbon atom double-bonded to an oxygen and single-bonded to a hydrogen)  Makes up formaldehyde and acetaldehyde

Ketone R-CO-R (contains a carbon atom double-bonded to an oxygen atom and then connected to carbon chains through the other two single bonds)   Makes up acetone

Fatty acid R-COOH (contains a carbon atom double-bonded to an oxygen atom, single-bonded to a hydroxyl, and single-bonded to the carbon chain) Makes up fatty acids like acetic acid and stearic acid; used to form esters

Ether R-O-R (contains double carbon chains connected to an oxygen atom through single bonds)   Ethyl ether is very volatile and flammable, used in veterinary medicine

3. Carbon is able to make four covalent bonds with other elements. This gives it a lot of diversity and the ability to form differently shaped molecules that perform specific functions or fit specific cell receptors in the body. H can form only one bond, and oxygen forms only two bonds, so they don't have as much potential to form a good starting point for organic molecules.

Explanation:

pf

CaO is not an organic compound because it doesn’t contain a carbon molecule.

(which contains a hydroxyl group)  Can be poisonous, can be made from fermentation or distillation

Aldehyde R-COH (contains a carbon atom double-bonded to oxygen and single-bonded to hydrogen)  Makes up formaldehyde and acetaldehyde

Ketone R-CO-1R (contains a carbon atom double-bonded to an oxygen atom and then connected to carbon chains through the other two single bonds)   Makes up acetone

Fatty acid R-COOH (contains a carbon atom double-bonded to an oxygen atom, single-bonded to a hydroxyl, and single-bonded to the carbon chain) Makes up fatty acids like acetic acid and stearic acid; used to form esters11

Ether -O-R (contains double carbon chains connected to an oxygen atom through single bonds)   Ethyl ether is very volatile and flammable, used in veterinary medicine

Carbon can make four covalent bonds with other elements. This gives it a lot of diversity and the ability to form differently shaped molecules that perform specific functions or fit specific cell receptors in the body. H can form only one bond, and oxygen forms only two bonds, so they don't have as much potential to form a good starting point for organic molecules.

Learn more about organic molecules.

https://brainly.com/question/24225576

#SPJ2

Answer:

P =40.69 atm

Explanation:

We need to find the approximate pressure at a depth of 400 m.

It can be calculated as follows :

P = Patm + ρgh

Put all the values,

[tex]P=1\ atm+1025 \times 9.81\times 400\times 9.8692\times 10^{-6}\ atm/Pa\\\\P=40.69\ atm[/tex]

So, the approximate pressure is equal to 40.69 atm.

Answer:

978.6084 Newton

Explanation:

Given the following data;

To find the weight in Newtown;

Conversion:

1 lb = 4.448220 N

220 lb = 220 * 4.448220 = 978.6084 Newton

220 lb = 978.6084 Newton

Therefore, the weight of the astronaut in Newton is 978.6084.

Weight can be defined as the force acting on a body or an object as a result of gravity.

Mathematically, the weight of an object is given by the formula;

Weight = mg

Where;

Note:

Answer:

Explanation:

Speed= distance/time

Or time = distance/speed

According to your question

Speed=15m/s

and. Distance=1.2km. ,we must change kilometer in meter because given speed is in m/s

D= 1.2km = 1.2×1000m =1200meter

Time = distance/ speed

1200/15 =80second

Or. 1min and 20 sec will be your answer.

Answer:

Henry Ford

Explanation:

he built the first ford

Answer:

Liquid volume is usually measured using either a graduated cylinder or a buret. As the name implies, a graduated cylinder is a cylindrical glass or plastic tube sealed at one end, with a calibrated scale etched (or marked) on the outside wall.

Answer:

Gravity between you and the sun

Answer:

the final velocity of the ball is 4.87 m/s

the final velocity of the ping ball is 9.87 m/s

Explanation:

Given;

mass of the ball, m₁ = 4.65 kg

mass of the ping ball, m₂ = 0.06 kg

initial velocity of the ping ball, u₂ = 0

initial velocity of the ball, u₁ = 5 m/s

let the final velocity of the ball = v₁

let the final velocity of the ping ball, = v₂

Apply the principle of conservation of linear momentum for elastic collision;

m₁u₁  +  m₂u₂  = m₁v₁   +  m₂v₂

4.65(5)  +   0.06(0)   =   4.65v₁   +   0.06v₂

23.25 + 0 = 4.65v₁  +  0.06v₂

23.25 = 4.65v₁  +  0.06v₂  ------ (1)

Apply one-directional velocity equation;

u₁ + v₁ = u₂  +  v₂

5 + v₁ = 0  +  v₂

5 + v₁ = v₂

v₁ = v₂ - 5  -------- (2)

substitute equation (2) into (1)

23.25 = 4.65(v₂ - 5)  +  0.06v₂

23.25 = 4.65v₂  -  23.25   +   0.06v₂

46.5 = 4.71 v₂

v₂ = 46.5/4.71

v₂ = 9.87 m/s

v₁ = v₂ - 5

v₁ = 9.87 - 5

v₁ = 4.87 m/s

Answer:

f = 7.06 N

Explanation:

The maximum frictional force on the knee joint of the person can be given by the following formula:

[tex]f = \mu R = \mu W \\[/tex]

where,

f = maximum frictional force = ?

μ = static friction coefficient = 0.016

W = Weight load on knee = mg

m = mass supported by knee = 45 kg

g = acceleration due to gravity = 9.81 m/s²

Therefore,

[tex]f = \mu mg\\f = (0.016)(45\ kg)(9.81\ m/s^2)\\[/tex]

f = 7.06 N

Answer:

hi the question isn't obvious and need a photo I guess

Answer:

The distance of a mass 25g from the pivot​ is 18cm

Explanation:

Given

[tex]m_1 = 10g[/tex]

[tex]d_1 = 45cm[/tex]

[tex]m_2 = 25g[/tex]

Required

Distance of m2 from the pivot

To do this, we make use of:

[tex]m_1 * d_1 = m_2 * d_2[/tex] --- moments of the masses

So, we have:

[tex]10 * 45= 25* d_2[/tex]

[tex]450= 25* d_2[/tex]

Divide both sides by 25

[tex]18= d_2[/tex]

Hence:

[tex]d_2 = 18[/tex]

Answer:

665.25 Pa

Explanation:

Given data :

Weight of the disk, w = 45 N

Diameter, d = 30 cm

                    = 0.30 m

Therefore, radius of the disk,

[tex]$r=\frac{d}{2}$[/tex]

[tex]$r=\frac{0.30}{2}$[/tex]

   = 0.15 m

Now, area of the cylindrical disk,

[tex]$A=\pi r^2$[/tex]

[tex]$A=3.14 \times (0.15)^2$[/tex]

   [tex]$=0.07065 \ m^2$[/tex]

∴ The gauge pressure at the top of the oil column is :

   [tex]$p=\frac{w}{A}$[/tex]

   [tex]$p=\frac{47}{0.07065}$[/tex]

      = 665.25 Pa

Therefore, the gauge pressure is 665.25 Pa.

The definition of pressure allows to find the result for the pressure at the top of the oil cylinder is:

The pressure is defined by the relationship between perpendicular force and area.

          [tex]P = \frac{F}{A}[/tex]

where P is pressure, F is force, and A is area.

They indicate that the wooden cylinder weighs W = 45.0 N and has a diameter of d = 30 cm = 0.30 m.

The area is:

        A = π r² = [tex]\pi \frac{d^2}{4}[/tex]  

In the attachment we see a diagram of the forces, where the weight of the cylinder and the thrust are equal.

         B-W = 0

          B = W

The force applied to the liquid is the weights of the cylinder. Let's replace.

          [tex]P= \frac{W}{A} \\P = W \frac{4}{\pi d^2 }[/tex]  

Let's calculate.

          [tex]P = \frac{45 \ 4 }{\pi \ 0.30^2 }[/tex] P = 45 4 / pi 0.30²

          P = 636.6 Pa

In conclusion using the definition of pressure we can find the result for the pressure at the top of the oil cylinder is:

Learn more about pressure here: brainly.com/question/17467912

Answer:

   a = w² r

Explanation:

In this exercise, indicate that the wheel has angular velocity w, the worm experiences the same angular velocity if it does not move, and has an acceleration towards the center of the circle, according to Newton's second law, called the centripetal acceleration.

           a = v² / r

angular and linear variables are related

           v = w r

we substitute

          a = w² r

where r is the radius of the wheel

Answer:

[tex]T=66262.4s[/tex]

Explanation:

From the question we are told that:

Altitude [tex]A=2.90 *10^7[/tex]

Mass [tex]m=5.97 * 10^{24} kg[/tex]

Radius [tex]r=6.38 *10^6 m.[/tex]

Generally the equation for Satellite Speed is mathematically given by

[tex]V=(\frac{GM}{d} )^{0.5}[/tex]

[tex]V=(\frac{6.67*10^{-11}*5.97 * 10^{24}}{6.38 *10^6+2.90 *10^7} )^{0.5}[/tex]

[tex]V=3354.83m/s[/tex]

Therefore

Period T is Given as

[tex]T=\frac{2 \pi *a}{V}[/tex]

[tex]T=\frac{2 \pi *(6.38 *10^6+2.90 *10^7}{3354.83}[/tex]

[tex]T=66262.4s[/tex]

Answer: I think its A or C I'm not sure though sorry.

Answer:

19N to the south

Explanation:

F =10N + 5N + 4N

Answer:

1.56 m/s²

Explanation:

Projectile motion is a form of motion where an object moves in parabolic path (trajectory). Projectile motion only occurs when there is one force applied at the beginning on the trajectory, after which the only interference is from gravity.

The total time (time of flight) of an object is given by:

T = 2usinθ / g

where u is the initial velocity, θ is the angle with horizontal and g is the acceleration due to gravity

Since the astronaut throws a rock straight up, hence θ = 90°, u = 19 m/s, T = 24.4 s.

T = 2usinθ / g

Substituting:

24.4 = 2(19)(sin90)/g

g = 2(19)(sin90) / 24.4

g = 1.56 m/s²

Answer:

W/7

Explanation:

By principle of moments,

Sum of clockwise moment = sum of anticlockwise moment

Weight × 7d = W × d

Weight = W/7

Since the two children are in rotational equilibrium, the weight of the second child is W/7.

The weight of the second child can be determined from the principle of moments.

The principle of moments states that for a body in equilibrium, the sum of the clockwise moments and anticlockwise moments about a point is zero.

Let the weight of the second child be X

From the principle of moments:

W × d = 7×d × X

X = W/7

Therefore, the weight of the second child is W/7.

Learn more about principle of moments at: https://brainly.com/question/20298772

Answer:

f = 1 m

Explanation:

The magnification of the lens is given by the formula:

[tex]M = \frac{q}{p}[/tex]

where,

M = Magnification = 4

q = image distance = 5 m

p = object distance = ?

Therefore,

[tex]4 = \frac{5\ m}{p}\\\\p = \frac{5\ m}{4}\\\\p = 1.25\ m[/tex]

Now using thin lens formula:

[tex]\frac{1}{f}=\frac{1}{p}+\frac{1}{q}\\\\\frac{1}{f} = \frac{1}{1.25\ m}+\frac{1}{5\ m}\\\\\frac{1}{f} = 1\ m^{-1}\\\\[/tex]

f = 1 m