Answer:
102000N/m2
This is the same as 102KN/m2 (where K = 10^3):
Explanation:
The expression 750 mmHg means 750 height the atmospheric pressure will cause mercury to be suspended due to gravity.
If we brought another fluid under investigation under the influence of the atmospheric pressure the height would be different)
Note that 750 mmHg would be the same as 750/1000 m Hg ( when we convert the mm to m)
0.75mHg
Now to get the pressure in N/m2.
We multiply the height of mercury by the density by the acceleration due to gravity.
This is expressed mathematically thus;
H×d × g ; let d- denote density
Hence we have;
H×d × g = 0.75 × 13600 × 10= 102000N/m2;
Now let's look at the flip.side assuming you don't know the formula for what you require you could use the idea of Unit derivation ;
The unit of interest is N/m2
The unit of height is m
The unit of density is kg/m3
The unit of g is Nkg-1
We would observe if we multiply
m × N/Kg × Kg/m3
We would have (m× N × Kg)/(kg×m3)
Kg cancels out, m cancels out one m from me remaining m2.
Hence our unit becomes N/m2
Note : the unit for density is wrongly expressed remember density is Mass/ volume and their units are respectively kg/m3
The atmospheric pressure on a particular day was measured as 750 mm of Hg. this would be in 102000 N/m² ( By Assuming the density of
mercury is 13600 kg/m3 and g =10Nkg-1
What is pressure?The total applied force per unit of area is known as the pressure.
The pressure depends both on externally applied force as well the area on which it is applied.
The mathematical expression for the pressure
Pressure = Force /Area
the pressure is expressed by the unit pascal or N /m²
As given in the problem The atmospheric pressure on a particular day was measured as 750 mm of Hg.
Atmospheric pressure is measured by the formula
P = ρgh
where ρ is the density of the mercury
g is the acceleration due to gravity
h is the height of the liquid
By substituting the respective values
P = 13600*10*(750/1000)
P = 102000 N/m²
Thus, the atmospheric pressure would be 102000 in N/m².
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Two people try to lift a heavy box. Jack pulls upward with a 100-newton
force. Jill pulls upward with a 50-newton force, but neither person moves the
box.
Compare the amount of work done on the box by Jack and Jill.
OA) Jack did twice as much work as Jill.
OB) Jack did fifty times more work than Jill.
OC) Jack and Jill did the same amount of work.
Answer:
A ( Jack did twice as much work as Jill
Explanation:
the components and functionality of the event horizon telescope.
Answer:
The Event Horizon Telescope comprises of a an interconnection of radio observatories. These radio observatories work in unison and helps in efficient observation of radio sources associated with black holes with angular resolution in comparison to their event horizons. This equipment functions by ensuring that anything or light which goes through the event horizon cannot escape from the black hole. Instead there will be a continual falling towards the center of the black hole.
A rocket is launched from atop a 101 foot cliff with an initial velocity of 116 ft/s.
\a. Substitute the values into the vertical motion formula h(t) = -16t2 + vt + h0 . Let h(t) = 0
b. How long will the rocket take to hit the ground after it is launched? Round to the nearest tenth of a second.
Answer:
A. 16t2 -116t -101=0 B. 8.0s
Explanation:
Known parameters from the question:
Height of Cliff,h0 = 101ft
Velocity of rocket ,v= 116ft/s.
1.Substituting the above to the above formula we have;
h(t) = -16t2 + vt + h0
Since h(t) =0, it means the rocket is falling towards the ground, when it gets to the ground when it's at rest the height h(t) = 0m
{Note the rocket is launched from the height of the Cliff so that would be the initial height of the rocket,h0}
2.Substituting into h(t) = -16t2 + vt + h0
We have;
0 = -16t2 + 116t + 101=> 16t2 -116t -101=0
Using formula method for solving quadratic equation we have;
t = -(-116)+_√[(-116)^2 -( 4× 16 ×-101]/ (2× 16)
t = [116 +_(141.1382)]/32
t = (116 -141.1382)/32 or (116 +141.1382)/32
-0.786s or 8.036s
-0.8s or 8.0s to the nearest tenth.
Now time cannot be negative in real life situation hence the time is 8.0s
Note : the general equation of a quadratic equation with variable t is given below;
at2 + bt + c=0
Formula method for quadratic equation is :
t =( -b+_√[(b^2 -( 4× a×c)] ) / (2× a)
10) Um viajante, ao desembarcar no aeroporto de Londres, observou que o valor da temperatura do ambiente na escala Fahrenheit é o quíntuplo do valor da temperatura na escala Celsius. Calcule essa temperatura
Answer:
The observed temperature was 10º Celsius or 50º Fahrenheit.
Explanation:
The traveler observed that the temperature in Fahrenheit is five times the value of the temperature in Celsius, therefore:
[tex]F = 5*C[/tex]
A Fahrenheit temperature relates to a Celsius one by the following expression:
[tex]F = \frac{9}{5}*C + 32[/tex]
Using the second expression on the first, we can solve for the temperature in Celsius, this is done below:
[tex]\frac{9}{5}*C + 32 = 5*C\\\frac{9}{5}*C - 5*C = -32\\\frac{9*C - 25*C}{5} = -32\\\frac{-16*C}{5} = -32\\-16*C = -32*5\\-16*C = -160\\C = \frac{-160}{-16} = 10\º\text{C}\\F = 5*C = 5*10 = 50\º\text{F}[/tex]
The observed temperature was 10º Celsius or 50º Fahrenheit.
4. ____________ occurs when one object slides over another.
a. Sliding friction
b. Static friction
c. Rolling friction
d. Net force
Answer:
A. Sliding friction
Explanation:
Sliding friction is weaker than static friction
Answer:
Rolling Friction
Explanation:
I know this because the definition of rolling friction is : type of friction that happens when one body rolls over another
A sphere of radius 0.03m has a point charge of q= 7.6 micro C located at it’s centre. Find the electric flux through it?
Answer:
The electric flux through the sphere is [tex]8.58 *10^{5} \frac{Nm^2}{C}[/tex]
Explanation:
Given
[tex]Radius,\ r = 0.03m\\Charge,\ q =7.6\µC[/tex]
Required
Find the electric flux
Electric flux is calculated using the following formula;
Ф = q/ε
Where ε is the electric constant permitivitty
ε [tex]= 8.8542 * 10^{-12}[/tex]
Substitute ε [tex]= 8.8542 * 10^{-12}[/tex] and [tex]q =7.6\µC[/tex]; The formula becomes
Ф = [tex]\frac{7.6\µC}{8.8542 * 10^{-12}}[/tex]
Ф = [tex]\frac{7.6 * 10^{-6}}{8.8542 * 10^{-12}}[/tex]
Ф = [tex]\frac{7.6}{8.8542} *\frac{10^{-6}}{10^{-12}}[/tex]
Ф = [tex]\frac{7.6}{8.8542} *10^{12-6}}[/tex]
Ф = [tex]0.85834970974 *10^{12-6}}[/tex]
Ф = [tex]0.85834970974 *10^{6}}[/tex]
Ф = [tex]8.5834970974 *10^{5}}[/tex]
Ф = [tex]8.58 *10^{5} \frac{Nm^2}{C}[/tex]
Hence, the electric flux through the sphere is [tex]8.58 *10^{5} \frac{Nm^2}{C}[/tex]
If mass = 30kg, gravity = 10 N/kg and height is 2m of a car. Calculate the gravitational potential energy.
Answer:
P.E.=600Nm
Explanation:
m=30kg
g=10m/s²
h=2m
P.E.=?
as we know that
P.E.=mgh
P.E.=30kg×10m/s²×2m
P.E.=600Nm
Use the worked example above to help you solve this problem. An Alaskan rescue plane drops a package of emergency rations to stranded hikers, as shown in the figure. The plane is traveling horizontally at 39.0 m/s at a height of 1.50 102 m above the ground. (a) Where does the package strike the ground relative to the point at which it was released? (b) What are the horizontal and vertical components of the velocity of the package just before it hits the ground? horizontal and vertical (c) Find the angle of the impact.
Answer:
(a) The package lands 682 meters horizontally ahead from the point the package was dropped from the plane
(b) The horizontal component = 39.0 m/s
The vertical component = 171.55 m/s
(c) The angle of impact is 77.19°
Explanation:
The parameters given are;
Velocity of the plane, vₓ = 39.0 m/s
Height of the plane above the ground, h = 1.50 × 10² m = 1,500 m
(a) The time, t, before the package hits the ground when dropped from the plane is given by the relation;
h = u·t + 1/2×g×t²
Where:
g = Acceleration due to gravity = 9.81 m/s²
u = Initial vertical velocity = 0 m/s
Hence;
1500 = 0×t + 1/2 × 9.81 × t² = 4.905·t²
∴ t = √(1500/4.905) = 17.49 s
The horizontal distance the package travels before landing = 17.49 × 39 ≈ 682 m
The package lands 682 meters horizontally ahead from the point the package was dropped from the plane
(b) The vertical velocity, [tex]v_y[/tex], of the package just before landing is given by the relation;
[tex]v_y[/tex]² = u² + 2·g·h
u = 0 m/s
∴ [tex]v_y[/tex]² = 0 + 2×9.81×1500 = 29430 m²/s²
[tex]v_y[/tex] = √29430 = 171.55 m/s
Hence the horizontal component = 39.0 m/s
The vertical component = 171.55 m/s
(c) The angle of impact, θ, is given as follows;
[tex]tan \theta = \dfrac{v_y}{v_x} = \dfrac{171.55}{39.0 } = 4.4[/tex]
∴ θ = tan⁻¹(4.4) = 77.19°.
The object will feel minimum force of gravity at the
Answer:
space , small amount of gravity is found in the space ,infact we can say that there is no gravity in the space
Answer:
Poles
Explanation:
The gravitational force is maximum at the equator and minimum at the poles.
Assume that a machine puts out 8000 joules of work when the user puts in 10,000 joules of work. What is the efficiency of the machine?
Answer:
80 Percent
Explanation:
E=energy output/energy input×100
E=8000/10000×100
E=0.8×100
E=80 percent.
Mark brianliest if my answer suit your question
If the machine put, in 8000 J, and the user puts 10,000 J of work then the efficiency of the machine will be equal to 80%.
What is Work?Work is a physics term used to describe the transfer of energy that takes place when an object changes above a distance because of an external force, at least some of which is given in the vector of the dislocation. The element of the force acting all along the path multiplied by the length of the path can be used to calculate work if the force is constant.
Mathematically, this idea is expressed as W = fd, where W is the effort and f is the force multiplied by d, the distance. Work is completed whenever the force is applied at an angle with about the displacement.
As per the data provided in the question,
Total input energy = 10,000 J
Total output energy = 8,000 J
Then, the efficiency (η) of the machine will be,
η = (output energy/input energy) × 100
η = 8000/10000 × 100
η = 80%.
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find the period of a simple pendulum of 1m length placed on earth and on moon g on moon =1.67m/s² g on earth=10m/s²
Answer:
[tex]T_{m }[/tex] = 4.86 s
[tex]T_{e}[/tex] = 1.98 s
Explanation:
Given:
Length = l = 1 m
Acceleration due to gravity of moon = [tex]g_{m}[/tex] = 1.67 m/s²
Acceleration due to gravity of Earth = [tex]g_{e}[/tex] = 10 m/s²
Required:
Time period = T = ?
Formula:
T = 2π [tex]\sqrt{\frac{l}{g} }[/tex]
Solution:
For moon
Putting the givens,
T = 2(3.14) [tex]\sqrt{\frac{1}{1.67} }[/tex]
T = 6.3 [tex]\sqrt{0.6}[/tex]
T = 6.3 × 0.77
T = 4.86 sec
For Earth,
Putting the givens
T = 2π [tex]\sqrt{\frac{1}{10} }[/tex]
T = 2(3.14) [tex]\sqrt{0.1}[/tex]
T = 6.3 × 0.32
T = 1.98 sec
How does charging by conduction work?
Answer:
During charging by conduction, both objects acquire the same type of charge. If a negative object is used to charge a neutral object, then both objects become charged negatively. ... In this case, electrons are transferred from the neutral object to the positively charged rod and the sphere becomes charged positively.
Talia is on a trip with some friends. In the first 2 hours , they travel 100 miles. Then they hit traffic and go only 30 miles in the next hour. The last hour of their trip , they drive 75 miles
Answer:
51 miles/hour
Explanation:
Talia is on a road trip with some friends. in the first 2 hours, they travel 100 miles. then they hit traffic and go only 30 miles in the next hour. the last hour of their trip, they drive 75 miles. calculate the average speed of talia’s car during the trip. give your answer to the nearest whole number.
The average speed would be 51 miles/hour.
The average speed of a moving object is defined as the total distance traveled relative to the total time taken fro the journey. Mathematically, it is given as:
total distance traveled/total time taken.
In this case;
Total distance traveled = 100 + 30 + 75 = 205 miles
Total time taken = 2 + 1 + 1 = 4 hours
Therefore;
Average speed = 205/4 = 51.25 miles/hour
To the nearest whole number = 51 miles/hour
What is the symbol for Pressure ? Help
Answer:
The answer is Pascal or Pa.
Answer:
Pa or small p
Explanation:
Force over Area. The SI unit is Pascal
what are two things that are infinite?
Answer:
Infinity = Never ending
Explanation:
The universe could be infinite, both in terms of space and time, but there is currently no way to test whether it goes on forever or is just very big. The part of the universe we are able to observe is finite, measuring about 46 billion light years in diameter.
The set of natural numbers is an infinite set. This kind of infinity is, by definition, called countable infinity. All sets that can be put into a bijective relation to the natural numbers are said to have this kind of infinity. This is also expressed by saying that the cardinal number of the set is aleph-naught (ℵ0).
Hope this helps. Mark as brainliest!
STARS ARE INFINITE , NUMBERS ARE INFINITE
Explanation:
What would Genaris and her classmates most likely do to
test this idea?
its
Explanation:
they would formulate a new hypothesis with the same dependent variable but a different independent variable as a virginal hypothesis .
A student drops two metallic objects into a 120 g steel container holding) 150 g of water at 25°C. One object is a 253 g cube of copper that is initially at 85°C, and the other is a chunk of aluminum that is initially at 5°C. To the surprise of the student, the water reaches a final temperature of 25°C, its initial temperature. What is the mass of the aluminum chunk? (please add an explanation)
Answer: 0.326kg
Explanation:
Given the following :
Mass of copper (Mc) = 253g
Initial temperature of copper (t1) = 85°C
Mass of aluminium(Ma)=?
Initial temperature of aluminum(t1) = 5°C
Specific heat capacity of aluminum(Ca) = 900
Specific heat capacity of copper (Cc) = 387
Final temperature(t2) = 5°C
Q = mc(t2 - t1)
Ma × Ca × (t2 - t1)a = Mc × Cc × (t2 - t1)c
Ma × 900 × (25 - 5) = 0.253 × 387 × (25 - 85)
Ma × 900 × 20 = 0.253 × 387 × 60
Ma × 18000 = 5874.66
Ma = 5874.66 / 18000
Ma = 0.32637
Ma = 0.326kg
The mass of the aluminum chunk dropped into the water is 325.5 g.
The given parameters;
mass of the steel, = 120 gmass of water = 150 ginitial temperature of water = 25 °Cmass of copper = 253 ginitial temperature of the copper = 85 °Cinitial temperature of the aluminum = 5 °Cfinal temperature of water = 25 °CSpecific heat capacity of aluminum = 0.9 J/gC Specific heat capacity of copper = 0.386 J/gCApply the principle of conservation of energy, the heat gained by the aluminum is equal to heat lost by the copper;
[tex]M_a C_a (t- t_a) = M_c C_c (t_c - t)\\\\M_a\times 0.9 \times (25-5) = 253 \times 0.386 \times (85-25)\\\\18 M_a = 5859.48\\\\M_a = \frac{5859.48}{18} \\\\M_a = 325 .5 \ g[/tex]
Thus, the mass of the aluminum chunk dropped into the water is 325.5 g.
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A box that has a mass of 80 kg slides down a ramp with a 30 degree angle. The free-body diagram shows the forces acting on the box. A block is shown on a 30-degree incline with a free body diagram drawn on the block with 2 force vectors. The first vector is pointing away from the surface of the incline and perpendicular to the surface, labeled F Subscript N Baseline. The second vector is pointing straight down to the center of the earth, labeled F Subscript g Baseline. Ignoring friction and air resistance, what is the acceleration of the box, to the nearest tenth? 0.5 m/s2 4.9 m/s2 8.5 m/s2 9.8 m/s2
HOW TO DO IT
Answer:
B. 4.9 m/[tex]s^{2}[/tex]
Explanation:
The parallel vector, [tex]F_{g}[/tex], make the box to accelerate down the plane due to the presence of an unbalanced force.
The perpendicular component of the force will balance the normal force because the box can not accelerate perpendicularly to the plane.
i.e [tex]F_{N}[/tex] = [tex]F_{g}[/tex]
Since the box slides down the ramp, neglecting friction and air resistance;
[tex]F_{g}[/tex] = ma
mg Sinθ = ma
But; m = 80 kg, θ = [tex]30^{0}[/tex], g = 9.8 m/[tex]s^{2}[/tex]
80 × 9.8 × Sin [tex]30^{0}[/tex] = 80 × a
784 × 0.5 = 80 a
392 = 80 a
a = [tex]\frac{392}{80}[/tex]
= 4.9
Thus, the box accelerates down the ramp at 4.9 m/[tex]s^{2}[/tex].
Answer:
b
Explanation:
b
Technological design leads to the development and innovation of new technologies.
Which statement represents innovation?
O Solar panels have increased in efficiency over the past 20 years.
O The Sun is the primary source of energy for the solar system
O Previous models of a type of car have fewer engine problems.
O Natural selection ensures that only the fittest survive.
Answer:
Solar panels have increased in efficiency over the past 20 years
Explanation:
Because if efficiency have increased other technologies will be discovered
Answer:
Solar panels have increased in efficiency over the past 20 years
Explanation:
In the equation for elastic potential energy below, what is represented by the symbol k? Ee = ½ × k × e²
Answer:
K is the spring/elastic constant measured in Newton per metre square (N/m²)
Explanation:
E = ½Ke²
In the equation above,
E is the energy in Joules (J)
K is the elastic/spring constant in Newton per metre square (N/m²)
e is the extension in metre (m)
Answer:
In the equation Ee = ½ × k × e², "k" = spring constant
Explanation:
Se realiza un trabajo mecanico de 3500 J para levantar una cubeta con area cuyo peso tiene una determinada magnitud. Determina la altura a la que se elevo la cubeta
Answer:
10 m
Explanation:
Trabajo (W) = 3500 J, peso de la cuchara (F) = 350 N.
El trabajo es el producto de la fuerza que actúa sobre un objeto y la distancia o desplazamiento. La unidad de trabajo estándar son los joules (J).
Trabajo (W) = fuerza (F) × distancia (d)
W = F × d
[tex]d=\frac{W}{F} =\frac{3500J}{350}=10m[/tex]
el cubo se elevó a 10 m
The height (distance) to which the bucket was raised is equal to 10 meters.
Given the following data:
Work done = 3500 JoulesWeight of bucket = 350 NewtonTo determine the height (distance) to which the bucket was raised:
Mathematically, work done is given by the formula:
[tex]Work\;done = Force \times distance[/tex]
Substituting the given parameters into the formula, we have;
Note: Force = weight.
[tex]3500 = 350 \times distance\\\\Distance = \frac{3500}{350}[/tex]
Distance = 10 meters.
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What is a resistor? A. a light bulb B.a switch C. a battery
Answer:
A resistor is a battery
Answer:
The answer is A
Explanation:
A resistor is a light bulb because it is the flow of an electric current in an electric circuit.
What are some potential sources of error in the
experiment that is described in the article?
Answer: experimental design
the accuracy of data-collecting devices
human error
bias in selecting samples
incorrect data analysis
incorrect treatment of the control group
Explanation:
Instrumental, environmental, procedural, and human errors are frequent causes. Depending on how they affect the outcomes, each of these errors can either be random or systematic.
What are Experimental Error?The discrepancy between a measured value and its true value is known as experimental error. In other words, the error or inaccuracies are what prevent us from perceiving a measurement that is 100 percent accurate.
Every measurement has some degree of experimental error, which is fairly common. Due to the widespread belief that some degree of error is inherent to the scientific method, it is not typically seen as a "mistake" in the classic sense.
However, scientists can reduce error and obtain results that are more accurate by embracing and comprehending the ways that experimental error can affect any scientific operation.
The potential sources of error in experiment are Instrumental, environmental, procedural, and human errors.
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A squeeze bottle squeezes when pressed. It regains its shape when pressed .It regains its shape when the pressure from your hand is withdrawn. What may happen if the squeeze bottle is pressed to take the sauce out and then immediately corked tightly? Will it regain its shape? If not, Why?
Answer: It will not regain its shape, because when it is corked it can not replace the volume of material that you just take out of it.
Explanation:
When you squeeze the bottle, you are changing the volume of the bottle, in this process, you are "expelling" the material inside the bottle.
When you stop squeezing, there is a change in pressure, and the bottle "absorbs" air, until the pressure is equilibrated, and in this process, the bottle returns to the original shape.
Now, if you take the sauce out of the bottle and immediately cored it, then you removed the material inside of the bottle and did not let the bottle to "refill" the empty space with air, so it can not regain its shape.
Suggest what would happen to the pressure of a gas at constant temperature if the volume of the gas is halved.
Answer:
8.31 m3-Pa/mol-K
Explanation:
A tuning fork is vibrating the air around it. What best describes the waves produced by the tuning fork?
Answer:
The water particles move in the same direction as the vibrating source of the sound wave. ... What best describes the waves produced by the tuning fork? mechanical, because the vibrating tuning fork makes air molecules around it vibrate. A wave is produced in a Slinky as shown.
Explanation:
Answer:
mechanical, because the vibrating tuning fork makes air molecules around it vibrate
Explanation:
1a. Assuming 100% efficient energy conversion, how much water stored behind a 50cm high hydroelectric dam would be required to charge a 50 ampere-minute 12 volt battery with 600j of energy stored in it
Answer:
7.22 m³ of water should be stored behind the hydroelectric dam.
Explanation:
First we find the total energy that can be stored in the battery. For that purpose we use the formula:
P = VI
where,
P = Power delivered by battery
V = Voltage of Battery = 12 volts
I = Current in Battery
Multiplying both sides by time interval (t), we get:
Pt = VIt
where,
Pt = (Power)(Time) = Total Energy Stored in Battery = E = ?
It = Current Rating of Battery = (50 A.min)(60 s/min) = 3000 A.s
Therefore,
E = (12 volt)(3000 A.s)
E = 36000 J
Now, we have to find the energy required to fully charge the battery:
Energy Required = ΔE = Total Energy Capacity(E) - Already Stored Energy
ΔE = 36000 J - 600 J
ΔE = 35400 J
Now, this energy must be equal to the potential energy of water stored behind hydroelectric dam to fully charge the battery, provided that the conversion efficiency is 100 %.
Therefore,
ΔE = mgh
where,
m = mass of water behind hydroelectric dam
g = 9.8 m/s²
h = height of dam = 50 cm = 0.5 m
Therefore,
35400 J = m(9.8 m/s²)(0.5 m)
m = (35400 J)/(4.9 m²/s²)
m = 7224.5 kg
Now, to find the volume of stored water, we use:
ρ = m/V
V = m/ρ
where,
ρ = density of water = 1000 kg/m³
V = Volume of water behind dam = ?
V = (7224.5 kg)/(1000 kg/m³)
V = 7.22 m³
what is the wavelength of the radio waves transmitted by an FM station at 90MHz where 1M=10^6 AND THE SPEED OF RADIOWAVE IS 3*10^8m/s
Answer: 0.3m
Explanation:
Given the following :
Speed of radio wave(V) = 3 × 10^8 m/s
If 1M = 10^6
Frequency(F) = 90MHz = 90 × 10^6
Wavelength (λ) =?
Speed of wave (V) = frequency(F) × wavelength(λ)
V = fλ
(3 × 10^8) = (90 × 10^6) × λ
λ = (90 × 10^6) / (3 × 10^8)
λ = 30 × 10^(6 - 8)
λ = 30 × 10^-2
λ = 0.3m
which of the following terms describes a machine that converts heat into work?
A. Entropy pump
B. Heat engine
C. Heat pump
D. Entropy engine
Answer: A
Heat engine
Explanation: just took the test
A non-uniform rod 60cm long and weighs 32N is balanced at the 45cm mark. A load of 2N is hung on the zinc rod at the 25cm mark. Where must a second knife-edge be placed to balance the zinc rod horizontally
Answer:
The second knife-edge must be placed 46.2 cm from the zero mark of the rod.
Explanation:
From the law of equilibrium, ΣF = 0 and ΣM = 0.
Let R be the reaction at the knife edge. Since the weight of the rod and zinc load act downward, and we take downward position as negative
-32 N - 2 N + R = 0
-34 N = -R
R = 34 N
Also, let us assume the knife-edge is x cm from the zero mark. Taking moments about the weight and assuming the knife-edge is right of the weight of the rod. Taking clockwise moments as positive and anti-clockwise moments as negative,
-(45 - 25)2 + (x - 45)R = 0
-(20)2 + (x - 45)34 = 0
-40 = -(x - 45)34
x - 45 = 40/34
x - 45 = 1.18
x = 45 + 1.18
x = 46.18 cm
x ≅ 46.2 cm
The second knife-edge must be placed 46.2 cm from the zero mark of the rod.
