A series circuit is shown in the diagram below. What is the potential drop across R₁? (R₂ = 20 Ω, R₂ = 40 Ω, R₃ = 60 Ω, V = 60 V) (Ohm's law: IR)
Answers
Answer:
Option B. 10 V.
Explanation:
The following data were obtained from the question:
Resistor 1 (R₁) = 20 Ω
Resistor 2 (R₂) = 40 Ω
Resistor 3 (R₃) = 60 Ω
Potential difference (V) = 60 V
Next, we shall determine the total resistance of the circuit.
The circuit is in series connection. Therefore the total resistance (R) can be obtained by adding up R₁, R₂ and R₃ together as shown below:
R = R₁ + R₂ + R₃
R = 20 + 40 + 60
R = 120 Ω
Therefore, the total resistance in the circuit is 120 Ω
Next, we shall determine the current flowing in the circuit.
Note: The same current will flow through each resistor since they are in series connection.
The current flowing in the circuit can be obtained as follow:
Potential difference (V) = 60 V
Total resistance (R) = 120 Ω
Current (I) =..?
V = IR
60 = I x 120
Divide both side by 120
I = 60/120
I = 0.5 A
Therefore, the current flowing in the circuit is 0.5 A
Now, we can calculate the potential drop across R₁ as follow:
Resistor 1 (R₁) = 20 Ω
Current (I) = 0.5 A
Potential difference cross R₁ (V₁) =.?
V₁ = IR₁
V₁ = 0.5 x 20
V₁ = 10 V
Therefore, the potential difference across R₁ is 10 V.
Related Questions
an elastic cord 61 cm long when a weight of 75N hangs from it, but 85cm when a weight of 210N hangs from it. what is the spring constant of the cord
Answers
Answer:
560 N/m
Explanation:
F = kx
75 N = k (0.61 m − L)
210 N = k (0.85 m − L)
Divide the equations:
2.8 = (0.85 − L) / (0.61 − L)
2.8 (0.61 − L) = 0.85 − L
1.708 − 2.8L = 0.85 − L
0.858 = 1.8L
L = 0.477
Plug into either equation and find k.
75 = k (0.61 − 0.477)
k = 562.5
Rounded to two significant figures, k = 560 N/m.
A 1,383 kg purple car is driving southbound on a road and collides with a 1,827 kg orange car, that was traveling 31.87 m/s eastbound. The two cars collide and stick, sliding 14.54 meters before coming to rest. What was the initial velocity of the two-car system just after the collision? Take the coefficient of friction to be 0.463, and the acceleration due to gravity to be 9.8 m/s2. Answer to two decimal places.
Answers
Answer:
Explanation:
We shall apply work energy theorem to calculate the initial velocity just after the collision .
Their kinetic energy will be equal to work done by friction .
force of friction = μ mg , where μ is coefficient of friction , m is total mass and g is acceleration due to gravity
force = .463 x 3210 x 9.8
= 14565.05 N
work done = force x displacement
= 14565.05 x 14.54 = 211775.88 J
now applying work energy theorem
1/2 m v² = 211775.88 , m is composite mass , v is velocity just after the collision
.5 x 3210 x v² = 211775.88
v² = 131.94
v 11.48 m /s
I REALLY NEED HELP WITH PHYSICS!! HELPPP!! I’m giving 50 points :)))
Answers
Answer:
59%
Explanation:
Data obtained from the question include the following:
Input temperature = 495 K
Output temperature = 293 K
Efficiency =?
The efficiency of the car engine can be obtained by multiplying the ratio of the output temperature to the input temperature by 100 as shown below:
Efficiency = output /input x 100
Efficiency = 293/495 x 100
Efficiency = 59.1 ≈ 59%
Therefore, the efficiency of the car engine is approximately 59%
Someone help me?
Isaac throws an apple straight up in the positive direction) from 15 m above the ground, reaching a
maximum height of 38 meters. Neglecting air resistance, what is the ball's velocity when it hits the
ground?
Answers
Answer:
-27.3 m/s
Explanation:
Given:
y₀ = 38 m
y = 0 m
v₀ = 0 m/s
a = -9.8 m/s²
Find: v
v² = v₀² + 2a (y − y₀)
v² = (0 m/s)² + 2 (-9.8 m/s²) (0 m − 38 m)
v = -27.3 m/s
Or, you can solve with energy.
PE = KE
mgh = ½ mv²
v² = 2gh
v = -27.3 m/s
When you urinate, you increase pressure in your bladder to produce the flow. For an elephant, gravity does the work. An elephant urinates at a remarkable rate of 0.0060 m3 (a bit over a gallon and a half) per second. Assume that the urine exits 1.0 m below the bladder and passes through the urethra, which we can model as a tube of diameter 8.0 cm and length 1.2 m. Assume that urine has the same density as water, and that viscosity can be ignored for this flow.
1) What is the speed of the flow? It is 1.2 m/s
2) If we assume that the liquid is at rest in the bladder (a reasonable assumption) and that the pressure where the urine exits is equal to atmospheric pressure, what does Bernoulli's equation give for the pressure in the bladder? (In fact, the pressure is higher than this; other factors are at work. But you can see that no increase in bladder pressure is needed!)
Answers
Answer:
1) v = 1.19 m / s , 2) P₁ = 9.308 10⁴ Pa
Explanation:
In this exercise we will simulate the emission of urine as a fluid mechanics system
1) they indicate the urine flow rate Q = 0.0060 m³ / s, they also give the diameter of the tube 8.0 cm, they ask us the speed.
Let's use the continuity equation
Q = v A
The area of a cycling tube is
A = π r² = π d² / 4
we substitute
Q = v π d² / 4
v = 4Q / π d²
let's calculate
v = 4 0.006 / (π 0.08²)
v = 1.19 m / s
2) they ask to find the pressure in the bladder, for this we use the Bernoulli equation, where the index is for the bladder and the index 2 is for the exit point
P₁ + ½ ρ v₁² + ρ g y₁ = P₂ + ½ ρ v₂² + ρ g y₂
in the exercise it indicates that the outlet pressure is equal to the atmospheric pressure P₂ = 1,013 10⁵ Pa, the velocity of the liquid in the bladder is v₁ = 0 and the height difference 1.0 m
P₁ = P₂ + ½ ρ v₂² + ρ g (y₂-y₁)
let's calculate
P₁ = 1.013₁ 10⁵⁵ + ½ 1000 1.19 + 1000 9.8 (0-1)
P₁ = 1.013 105 + 595 - 9800
P₁ = 9.308 10⁴ Pa
250 mL 0.1 M HCl solution is mixed with 250 mL
0.2 M NaOH. The concentration of OH- in the
mixture is
Answers
Answer:
The concentration of OH⁻ in the mixture is 0.05 M
Explanation:
The reaction of neutralization between HCl and NaOH is the following:
H⁺(aq) + OH⁻(aq) ⇄ H₂O(l)
The number of moles of HCl is:
[tex] n_{HCl} = C*V = 0.1 mol/L*0.250L = 0.025 moles [/tex]
Similarly, the number of moles of NaOH is:
[tex] n_{NaOH} = C*V = 0.2 mol/L*0.250L = 0.05 moles [/tex]
Now, from the reaction of HCl and NaOH we have the following number of moles of NaOH remaining:
[tex] n_{NaOH} = 0.05 moles - 0.025 moles = 0.025 moles [/tex]
Finally, the concentration of OH⁻ in the mixture is:
[tex]C =\frac{n_{NaOH}}{V_{T}}=\frac{0.025 moles}{0.250*2 L} = 0.05 moles/L[/tex]
Therefore, the concentration of OH⁻ in the mixture is 0.05 M.
I hope it helps you!
A man has a mass of 110kg. What is his weight?
Answers
His weight depends on where he is, because
Weight = (mass) x (gravity in the place where the mass is) .
For example:
-- If this man is on Mars, his weight is (110 kg) x (3.7 m/s²) = 408 Newtons
-- If he is on the Moon, his weight is (110 kg) x (1.6 m/s²) = 176 Newtons
-- If he is on Earth, his weight is (110 kg) x (9.8 m/s²) = 1,078 Newtons
-- If he is in a spacecraft coasting from one to another, his weight is zero.
SOMEONE HELP ME PLEASE!!!
a. What is the displacement of the car in the graph?
b. What distance has the car travelled?
Answers
Answer:
a. 2 m
b. 4 m
Explanation:
a. Assuming d is the position of the car, the displacement is the difference between the final position and the initial position. 3 m - 1 m = 2 m.
b. From t = 0 to t = 2.5, the car moves a distance of 3 m. From t = 2.5 to t = 4, the car moves another 1 m.
So the car moves a total distance of 4 m.
The three-dimensional arrangement of electron groups around the central atom is called ____.
A. Election-pair repulsion
B. Electronegativity
C. Geometric design
D. Electron-group geometry
Answers
Answer:
D. Electron - group geometry
Explanation:
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if you rub a balloon on your hair, it becomes charged, and as a result It can stick to your head without being held there. why doesn't it fall on the ground?
Answers
The balloon doesn't fall on the ground. Because the electrical field around your head disrupts Earth's gravitational field. Option A is correct.
What is the electrostatic force, and how does it work?It is a force imposed by one charge on another as a result of the field. The electrostatic force produced by one line charge on another line charge separated by r is determined by the charge potency of each charge as well as the separation distance between them.
When you brush a balloon against your hair, it charges up and can attach to your head without being kept in place.
Because the electrical field surrounding your head interrupts Earth's gravitational field, it does not fall to the earth.
Hence, option A is correct.
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A series combination of 12 Ω and 3 Ω is connected in parallel with another series combination of 6 Ω and 3 Ω. If a potential difference of 4 V is applied across it find the i) current drawn from the battery ii) current through 12 Ω resistor (iii)potential difference across 6 Ω resistor?
Answers
Answer:
Explanation:
Resultant of 12 and 3 ohm in series = 15 ohm
Resultant of 6 and 3 ohm = 9 ohm
Total resultant resistance of circuit = 15 x 9 / (15 + 9)
= 5.625 ohm
current drawn from battery = 4 / 5.625
= .711 A
ii )current through 12 ohm = 4 / (12 + 3 ) , because potential diff over 12 and 6 ohm will be 4 V .
current through 12 ohm = .267 A
iii )
current through 6 ohm
= .711 - .267
= .444 A
potential difference
= .444 x 6
= 2.664 V .
The robot HooRU is lost in space, floating around aimlessly, and radiates heat into the depths of the cosmos at the rate of 13.5 W. HooRU's surface area is 1.51 m^2 and the emissivity of its surface is 0.209. Ignore the radiation HooRU absorbs from the cold universe. What is HooRU's temperature?
Answers
Answer:
165.73 K
Explanation:
The computation of HooRU's temperature is shown below:-
As per the stefan's law, the power radiated by black body radiations which is
[tex]P = eA\sigma T^4[/tex]
where
A indicates surface area
e indicates emissitivity
T indicates temperature
now, we will put the values in the above equation
[tex]13.5 = 0.209 \times 1.51 \times \sigma \times T^4[/tex]
After solving the above equation we will get temperature which results
= 165.73 K
Therefore for computing the HooRU's temperature we simply applied the above formula.
Calculating heat gained, need help!!!
Q=(m)(c)(triangle T)
trial 1:
Q=(0.4)(4.186 J/kg)(78)=?
trial 2:
Q=(0.6)(4.186 J/kg)(78)=?
trial 3:
Q=(0.45)(4.186 J/kg)(75)=?
Answers
Explanation:
q = mCΔT
where m is mass,
C is specific heat capacity,
and ΔT is change in temperature.
Make sure all your units match. Assuming the substance is water, C = 4186 J/kg/°C.
Trial 1:
q = (0.4 kg) (4186 J/kg/°C) (78°C)
q = 130,600 J
Trial 2:
q = (0.6 kg) (4186 J/kg/°C) (78°C)
q = 195,900 J
Trial 3:
q = (0.45 kg) (4186 J/kg/°C) (75°C)
q = 141,300 J
Newton's Law of Gravitation can be used to show that if an object weighs w pounds on the surface of the earth, then its weight at a distance x from the center of the earth is W(x)=wR2x2 (for x≥R), where R=3960 miles is the radius of the earth. Estimate the altitude at which a 120- lb pilot would weigh 119.5 lb
Answers
Answer:In other words, with w = 130, W = 129.5, what is x?
You find this by plugging in the values for w, W and R and solving for x.
Note: x is the distance from the center. You were asked for the distance from the surface (the altitude) so there's one more calculation to do when you find x.
Explanation:
a physical quantity Z is given by z=ad/g .calculte the relatibe error in z
Answers
Answer:
e_{r} = Δa /a + Δd /Δ d + Δg / g
Explanation:
The error or uncertainty of a quantity is given by several factors, the most direct error is the absolute one that is given by the appreciation of the instruments, when some quantities obtained by a mathematical formula we must know how each error is programmed in the total error, we can see this with the relative error
the calculated quantity is Z
its relative error is
[tex]e_{r}[/tex] = ΔZ/Z = 1/Z (dZ /da Δa + dZ /dd Δd + dZ /dg Δg)
e_{r} = 1 / Z (d /g Δa + a /g Δd + ad !1/g²! Δg)
e_{r} = Δa /a + Δd /Δ d + Δg / g
notice that we take the worst case.
The measured quantities have absolute errors Da, Dd, Dg
Culture creates the context for behavior in society. true or false
Answers
Answer:
True every culture is diffrent and culture is the way to grow up, the people or things you live around, or the ways of life you follow or dress.
Explanation: The definition of culture is: means a particular set of customs, morals, codes and traditions from a specific time and place. All of that develops how a person may behave in society.
Answer:
true
Explanation:
just took the quiz
Bumper car A (331 kg) moving east at 3.87 m/s hit stationary car B (208 kg). After, the car A moves .88 m/s east. What is the velocity of car B?
Answers
Answer:
Ub = 221.99m/s
Explanation:
(Ma x Ua)+(Mb x Ub) = (Ma + Mb)V
(331 x 3.87)+(208 x Ub) = (331 + 208)88
(1257.8) + (208 x Ub) = 47432
(208 x Ub) = 47432 - 1257.8
(208 x Ub) = 46174.2
Ub = 46174.2/208 = 221.99m/s
Ub = 221.99m/s
Answer:
4.75
Explanation:
M1V1 + M2V2 = M1V3 + M2V4
[(331*3.87) , 90°] + 0 = [(331*0.888) , 90°] + M2V4
M2V4 = 987.042 , 90°
divide through by M2
V4 = 4.75 m/s east
A car travels 18 km / h to the northwest. What is the speed of this car seen from another car going south at 60 km / h?
Answers
Answer:
73.8 km/h
Explanation:
The velocity of object A relative to object B is:
v = va − vb
Let's say east is +x and north is +y, and angles are measured from +x.
The velocity of the first car in the x direction is:
18 km/h cos 135° = -9√2 km/h
The velocity of the first car in the y direction is:
18 km/h sin 135° = 9√2 km/h
The velocity of the second car in the x direction is:
60 km/h cos 270° = 0 km/h
The velocity of the second car in the y direction is:
60 km/h sin 270° = -60 km/h
The relative velocity in the x direction is:
vₓ = -9√2 km/h − 0 km/h = -9√2 km/h ≈ -12.7 km/h
The relative velocity in the y direction is:
vᵧ = 9√2 km/h − (-60 km/h) = 9√2+60 km/h ≈ 72.7 km/h
The speed, or magnitude of the velocity, is:
v = √(vₓ² + vᵧ²)
v = √((-12.7 km/h)² + (72.7 km/h)²)
v ≈ 73.8 km/h
The solubility of barium nitrate is 9.02 g/100 g H2O at 20°C. A 15.2 g sample of barium nitrate is added to 200.0 g of water at 20°C. Is the solution saturated, unsaturated, or supersaturated?
Answers
Answer:
The solution is unsaturated.
Explanation:
Saturated solutions are those solutions with the maximum amount of solute completely dissolved by the solvent. This indicates that although more solute is added, it does not dissolve. In this case the amount of solute is equal to the solubility coefficient.
The supersaturated solution is one in which the amount of solute exceeds the solubility of the solvent, that is, it has a greater amount of dissolved solute than that which it admits at that temperature. In this case a solution contains solute above the solubility coefficient.
A solution is considered to be unsaturated if the mass of dissolved solute is less than that corresponding to that of saturation. This indicates that it is possible to add more solute and that it dissolves. In this case the solution contains solute below the solubility coefficient.
The solubility of barium nitrate is 9.02 g/100 g H₂O at 20°C.
A 15.2 g sample of barium nitrate is added to 200.0 g of water at 20°C. This is: 15.2 g /200 g H₂O. Dividing by two you get: 7.6 g /100 g H₂O
Comparing with the solubility of barium nitrate, you can see that the mass of dissolved solute is less than the corresponding one. This indicates that the solution is unsaturated.
in a cricket match there are 5000 spectators counted 10 by 10 the number of significant figure in the measurement will be
Answers
Answer:
[tex]\boxed{3 \ Significant \ figures}[/tex]
Explanation:
Total spectators = 5000
Counted by the groups of ten, So at last the result will be:
=> 5000/10 = 500
Significant figures in 500 are 3
Find the net force and acceleration. 15 points. Will give brainliest!
Answers
Answer:
[tex]\boxed{F_{net} = 28.7 \ N}[/tex]
[tex]\boxed{a = 2.1 \ m/s^2}[/tex]
Explanation:
Finding the net force:
Firstly , we'll find force of Friction:
[tex]F_{k} = (micro)_{k}mg[/tex]
Where [tex](micro)_{k}[/tex] is the coefficient of friction and m = 13.6 kg
[tex]F_{k} = (0.16)(13.6)(9.8)\\[/tex]
[tex]F_{k} = 21.32 \ N[/tex]
Now, Finding the net force:
[tex]F_{net} = F - F_{k}\\F_{net} = 50 - 21.32\\[/tex]
[tex]F_{net} = 28.7 \ N[/tex]
Finding Acceleration:
[tex]a = \frac{F_{net}}{m}[/tex]
[tex]a = \frac{28.7}{13.6}[/tex]
[tex]a = 2.1 \ m/s^2[/tex]
Which of the following would cause the force of static friction to increase?
Answers
Answer:
Answer B) An increase in [tex]\mu_S[/tex]
Explanation:
Since we are talking about the force of static friction, due to its definition as the product between the normal force to the surface times the coefficient of static friction, the only two ways such force could increase is due to an increase in the normal force, or an increase in the coefficient of static friction [tex]\mu_S[/tex].
So the only valid answer is answer B)
Joan makes the device shown in her science class.
An illustration with a battery and ends labeled positive and negative. A wire is connected to the positive end of the battery and curls around an iron nail and connects back with the negative side of the battery.
What would happen to the magnetic field if she connects the battery in the opposite direction?
The field would stop.
The field would get stronger.
The field would reverse its poles.
The field would get weaker.
Answers
Answer:
The field would reverse its poles.
Explanation:
The current flow will reverse directions which will reverse the poles in the magnetic field created around the iron nail.
If she connects the battery in the opposite direction, the magnetic field would reverse its poles.
What is magnetic field?The magnetic field is the region of space where an object experiences the magnetic force and obtain magnetic properties.
A wire is connected to the positive end of the battery and curls around an iron nail and connects back with the negative side of the battery. This arrangement will let the current flow from the positive end of the battery towards the negative terminal of the battery.
If the battery is connected in the opposite direction, the current will flow from negative to positive terminal.
Therefore, If she connects the battery in the opposite direction, the magnetic field would reverse its poles.
Learn more about magnetic field.
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Average velocity is different than average speed because calculating average velocity involves a)Distance b)Time c)Motion d)Displacemnet
Answers
Answer:
D. Displacement
Explanation:
got it right on edge
Average velocity is different than average speed because calculating average velocity involves Displacement, therefore the correct option is option D.
What is Velocity?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. It can also be represented by the infinitesimal rate of change of displacement with respect to time. The unit of velocity is meter/second.
The mathematical expression for velocity is given by
velocity= displacement / time taken
In the displacement time graph the slope of the curve represent the velocity of the object ,the rate of change of velocity is known as the acceleration of the object .
In the velocity time graph the slope of the curve represent the acceleration of the body, The unit of acceleration is metre per second Square
The total distance traveled by an object is different than the total displacement covered by it because the displacement is a vector quantity and it is calculated on the basis of the shortest distance traveled by the body or object.
The main difference between the distance and the displacement is that displacement can be positive or negative or zero but distance can never be negative.
Let’s understand understand with example of average velocity ,suppose an object is moving with 200 m displacement covered in a time of 15 seconds then the average velocity of the object is 13.33 m/s.
Thus, average velocity is different than average speed because calculating average velocity involves Displacement, therefore the correct option is option D.
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What is the magnetic force on a particle that has 0.000500 C of charge and is moving at
2.50 10m/s to the right through a magnetic field that is 4.20 T and pointing away from
you? Specify both magnitude and direction in your answer.
Answers
Answer:
1.) F = 5.3×10^-3 N
2.) Positive y - direction
Explanation:
The parameters given are:
Charge q = 0.0005C
Velocity V = 2.5010 m/s
Magnetic field B = 4.2 T
Magnetic force F = BVqsinØ
F = BVq
since Ø = 90 degree
Substitute all the parameters into the formula
F = 4.2 × 2.5010 × 0.0005
Therefore, the magnetic force on a particle is F = 5.3 × 10^-3 N
2.) According to Fleming's left hand rule, the direction of the magnetic force will be perpendicular to the magnetic field which moving upward of the screen.
Answer:
it’s f=0.0005 x 2.5 x 10^5 x 4.20
F= 525 N
+ y direction (up)
Explanation:
got it right
(I) A hiker determines the length of a lake by listening for the echo of her shout reflected by a cliff at the far end of the lake. She hears the echo 2.5 s after shouting. Estimate the length of the lake.
Answers
Answer:
425 m
Explanation:
From the question,
v = 2x/t.................... Equation 1
Where v = speed of sound in air, x = Length of the lake, t = time.
make x the subject of the equation
x = vt/2............... Equation 2
Given: t = 2.5 s
Constant: v = 340 m/s.
Substitute these values into equation 2
x = 340(2.5)/2
x = 425 m.
Hence the length of the lake is 425 m
a man with mass 81 kg lies on the floor. what is the normal force on the man?
Answers
Answer:
Forces come in pairs, so the force of gravity (9.8 N) with the mans weight (794N) on the earth is counteracted with the normal force ( the force of the earth back on the man) which is the same
Explanation:
Forces are available in pairs, so the force of gravity (nine.8 N) with the man's weight (794N) on the planet is counteracted with the everyday force ( the pressure of the earth again on the man) that's identical.
What is the gravitational force?Gravitational force is a pressure that draws any items with mass. We name the gravitational force appealing as it constantly attempts to tug loads collectively, it never pushes them apart. In reality, every item, together with you, is pulling on each other objects inside the complete universe.
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Ionizing radiation is radiation of sufficient energy to produce charged atoms. All of these describe ionizing radiation. is radiation of sufficient energy to produce ions. is radiation of sufficient energy to remove electrons from atoms.
Answers
Answer:
Is radiation of sufficient energy to produce ions.
Is radiation of sufficient energy to remove electrons from atoms.
Explanation:
Ionization radiation is a radiation that travels at a high speed, and possesses sufficient speed to knock electrons off of an atom or a molecule, ionizing the atom. Ionization radiation can be made of travelling subatomic particles, or an electromagnetic wave with high energy, usually the types found at the end of the electromagnetic spectrum. Some subatomic particles that produce ionization are alpha particle, beta particles, and neutron. The electromagnetic waves with ionization abilities includes Gamma rays. -rays, and high energy ultraviolet rays.
A submarine emerges 1/9 of its volume when it partially floats on the sea surface. For make it completely submerge it is necessary to allow a volume of 50,000 [L] to enter of sea water whose density is 1,026 [g / cm3]. What is the weight of the submarine?
Answers
Answer:
4,524,660 N
Explanation:
Assuming the submarine's density is uniform, 1/9th of the submarine's mass is equal to the mass of the displaced water.
m/9 = (1026 kg/m³) (50 m³)
m = 461,700 kg
mg = 4,524,660 N
a body weights 28N at a height of 3200km from the earth surface.What will be the gravitational force on that body if its lies on the earth surface.
Answers
Answer:
The object would weight 63 N on the Earth surface
Explanation:
We can use the general expression for the gravitational force between two objects to solve this problem, considering that in both cases, the mass of the Earth is the same. Notice as well that we know the gravitational force (weight) of the object at 3200 km from the Earth surface, which is (3200 + 6400 = 9600 km) from the center of the Earth:
[tex]F_G=G\,\frac{M_E\,m}{d^2} \\28\,\,N=G\,\frac{M_E\,m}{9600000^2}[/tex]
Now, if the body is on the surface of the Earth, its weight (w) would be:
[tex]F_G=G\,\frac{M_E\,m}{d^2} \\w=G\,\frac{M_E\,m}{6400000^2}[/tex]
Now we can divide term by term the two equations above, to cancel out common factors and end up with a simple proportion:
[tex]\frac{w}{28} =\frac{9600000^2}{6400000^2} \\\frac{w}{28} =\frac{9}{4} \\\\ \\w=\frac{9\,*\,28}{4}\,\,\,N\\w=63\,\,N \\[/tex]