Answer:
F = 1400 N
Explanation:
It is given that,
Mass of the ball, m = 70 kg
It is moving with an acceleration of 20 m/s². We need to find the force exerted by the ball.
Force is given by the product of mass and acceleration. So,
F = ma
[tex]F=70\ kg\times \ 20m/s^2\\\\F=1400\ N[/tex]
So, the force of 1400 N is exerted by a metal ball.
2 Which invention was crucial to the development of cell theory?
Answer:
I guess i would say the microscope
Explanation:
Because of the microscope, we can see the cells.
6. What are the methods to control noise pollution?
Answer: Some of the ways to control noise pollution are as follows: (1) Control at Receiver's End (2) Suppression of Noise at Source (3) Acoustic Zoning (4) Sound Insulation at Construction Stages (5) Planting of Trees (6) Legislative Measures.
Answer:
You have to:
a) Improve your insulation.
b) Install a fence
c) Use modern Acoustic wall panels
d) Plant trees
e) Reduce electronic volumes,e.t.c.
Explanation:
okay.
What type of psychologist would help a place of business or a company find the best ways to help their employees and customers? Group of answer choices forensic psychologist health psychologist industrial organizational psychologist developmental psychologist
Answer:
The correct option is;
Industrial organizational psychologist
Explanation:
Industrial organizational psychology is a branch of the study of psychology that looks into the application of psychological principles and theories in industrial and organizational settings.
An industrial organizational psychologist provide support to organizations such analyzing orientation and behavior, assessment of the organization, training company personnel on how to be or become a good leader, design and development of organizational products , analysis of customer choices, the satisfaction of the customers, and the strategy the organization follows in marketing of their products such as to increase awareness and understanding of human behavior in a workplace setting.
Help please answer the two questions
Explanation:
this is it. hope u understand
obesity occurs due to (a) overeating of carbohydrates and fats(b) not eating enough carbohydrates and fats (c) overeating of vitamins and minerals (d) not eating enough vitamins and minerals
Answer:
B for BIG
Explanation:
carbs and fats is energy, if not being use or burned off, it'll be becomes body fat.
PLZ HELP ASAP!!!! THANK YOU The disturbance that occurs as longitudional waves travel through a medium can be described as a series of A:oscillations and refractions B:propagations and compressions C:destructions and constructions D:rarefactions and compressions
Answer:
D:rarefactions and compressions
Explanation:
Longitudinal waves are readily formed in materials such as a stretched spring. Longitudinal waves are waves which travel in a direction parallel to the vibrations of the medium.
Longitudinal waves are characterized by a series of compressions and rarefactions. The compressions are areas of clusters while rarefactions are areas of expansions. The same can be observed in a sound wave.
In a Young's double-slit experiment, a set of parallel slits with a separation of 0.102 mm is illuminated by light having a wavelength of 575 nm and the interference pattern observed on a screen 3.50 m from the slits.(a) What is the difference in path lengths from the two slits to the location of a second order bright fringe on the screen?(b) What is the difference in path lengths from the two slits to the location of the second dark fringe on the screen, away from the center of the pattern?
Answer:
Rounded to three significant figures:
(a) [tex]2 \times 575\; \rm nm = 1150\; \rm nm = 1.15\times 10^{-6}\; \rm m[/tex].
(b) [tex]\displaystyle \left(1 + \frac{1}{2}\right) \times (575\;\rm nm) \approx 863\; \rm nm = 8.63\times 10^{-7}\; \rm m[/tex].
Explanation:
Consider a double-slit experiment where a wide beam of monochromatic light arrives at a filter with a double slit. On the other side of the filter, the two slits will appear like two point light sources that are in phase with each other. For each point on the screen, "path" refers to the length of the segment joining that point and each of the two slits. "Path difference" will thus refer to the difference between these two lengths.
Let [tex]k[/tex] denote a natural number ([tex]k \in \left\lbrace0,\, 1,\, 2,\, \dots\right\rbrace[/tex].) In a double-split experiment of a monochromatic light:
A maximum (a bright fringe) is produced when light from the two slits arrive while they were in-phase. That happens when the path difference is an integer multiple of wavelength. That is: [tex]\text{Path difference} = k\, \lambda[/tex].Similarly, a minimum (a dark fringe) is produced when light from the two slits arrive out of phase by exactly one-half of the cycle. For example, The first wave would be at peak while the second would be at a crest when they arrive at the screen. That happens when the path difference is an integer multiple of wavelength plus one-half of the wavelength: [tex]\displaystyle \text{Path difference} = \left(k + \frac{1}{2}\right)\cdot \lambda[/tex].MaximaThe path difference is at a minimum (zero) at the center of the screen between the two slits. That's the position of the first maximum- the central maximum, a bright fringe where [tex]k = 0[/tex] in [tex]\text{Path difference} = 0[/tex].
The path difference increases while moving on the screen away from the center. The first order maximum is at [tex]k = 1[/tex] where [tex]\text{Path difference} = \lambda[/tex].
Similarly, the second order maximum is at [tex]k = 2[/tex] where [tex]\text{Path difference} = 2\, \lambda[/tex]. For the light in this question, at the second order maximum: [tex]\text{Path difference} = 2\, \lambda = 2 \times 575\; \rm nm = 1.15\times 10^{-6}\; \rm m[/tex].
Central maximum: [tex]k = 0[/tex], such that [tex]\text{Path difference} = 0[/tex].First maximum: [tex]k = 1[/tex], such that [tex]\text{Path difference} = \lambda[/tex].Second maximum: [tex]k = 2[/tex], such that [tex]\text{Path difference} = 2\, \lambda[/tex].MinimaThe dark fringe closest to the center of the screen is the first minimum. [tex]\displaystyle \text{Path difference} = \left(0 + \frac{1}{2}\right)\cdot \lambda = \frac{1}{2}\, \lambda[/tex] at that point.
Add one wavelength to that path difference gives another dark fringe- the second minimum. [tex]\displaystyle \text{Path difference} = \left(1 + \frac{1}{2}\right)\cdot \lambda[/tex] at that point.
First minimum: [tex]k =0[/tex], such that [tex]\displaystyle \text{Path difference} = \frac{1}{2}\, \lambda[/tex].Second minimum: [tex]k =1[/tex], such that [tex]\displaystyle \text{Path difference} = \left(1 + \frac{1}{2}\right)\cdot \lambda[/tex].For the light in this question, at the second order minimum: [tex]\displaystyle \text{Path difference} = \left(1 + \frac{1}{2}\right)\cdot \lambda = \left(1 + \frac{1}{2}\right)\times (575\; \rm nm) \approx 8.63\times 10^{-7}\; \rm m[/tex].
A spring of initial length 35 cm acquires a length of 55 cm when we hang from it a mass of 3.5 kg. Calculate:
a) The elastic constant of the spring.
b) The length of the spring when we hang a mass of 5 Kg.
Answer:
the elastic constant of the spring=1.715
the length of the spring=0.28
Explanation:
we know that according to hooks law
F=-k x
F= force
k= elastic constant
x= extension or compression
given
length change from 35cm to 55 cm so delta x = L2-L1= 55-35=20 cm
now to find k we need F and F =ma
M for part a is 3.5 kg
so F=3.5 kg *9.8=34.3
now k=F/x
k=34.3/20=1.715 N/cm=171.5 N/m
now to find length given mass is 5 kg so
F= ma
F=5*9.8=49 N
so x =F/k
x=49/171.5
x=0.28
All large radioactive atoms decay into smaller atoms by releasing alpha particles. Each alpha particle has 2 protons, 2 neutrons, and 0 electrons. The table below describes several neutral, low-mass atoms.
A 4-column table with 4 rows, labeled Stable Isotopes of Low-Mass Elements. The first column labeled element name has entries hydrogen, helium, lithium, beryllium. The second column labeled symbol has entries H, H e, L i, B e. The third column labeled atomic number has entries 1, 2, 3, 4. The fourth column labeled number of neutrons has entries 0, 2, 4, 5.
An alpha particle is also referred to as a nucleus of which isotope?
lithium-7
helium-4
hydrogen-2
helium-2
Answer: Helium=4 is the answer
Explanation:
took the test and got it right that'
s the answer.
Answer:
It's b
Explanation:
I took the quiz on EDGE and got it right.
The distance covered by a body along the x axis is given by x=2t^3+5t^2+t where t is measured in seconds and x is in meter. Find average speed in a time interval from t= 0s and t=2s
Explanation:
It is given that,
The distance covered by a body along the x-axis is given by :
[tex]x=2t^3+5t^2+t[/tex]
t is in seconds and x is meters
Speed of the body is given by :
[tex]v=\dfrac{dx}{dt}\\\\v=\dfrac{d(2t^3+5t^2+t)}{dt}\\\\v=6t^2+10t+1[/tex]
At t = 0,
[tex]v=6(0)^2+10(0)+1=1\ m/s[/tex]
At t = 2 s,
[tex]v=6(2)^2+10(2)+1=45\ m/s[/tex]
So, the average speed in a time interval from t= 0s and t=2s is 45 m/s.
In 1869, Dmitri Mendeleev was trying to arrange the 65 known elements in a logical way. He arrived at the solution when he saw the elements arranged by atomic weight in a dream. He tried this arrangement and it worked! What is this an example of?
Answer:
Creative thinking
Explanation:
As you can see in the question above, when Mandleev needed to organize the chemical elements in a logical, organized and efficient way, he thought until he came to the conclusion of organizing them according to the atomic weight of each one. This is a clear example of creative thinking, which is the term that refers to the act of solving a problem based on thought and reasoning.
Answer:
Creative thinking
Explanation:
explore how archemides principle is applied in building a ship and submarine
Answer:
Principle Archimedes is applied in building a ship and submarine using the manipulating that buoyancy, is controlled the ballast tank system.
Explanation:
Submarine is rather had they focused on main parts of the submarine,he is complex and long process implementation,the most submarine design like submarine stability.
Submarine stability is complete and the fundamental Archimedes principle to arrive the weight of submarine is equal to buoyancy force.
Submarine into the parts and components of ballast tank the sequence in diving and surfacing,there two vital parts:- flood parts and air vents
flood parts:- at the bottom position and allow water to enter or leave that tank.
air vents:- air vents at the top of the pressure hall,and that they submarine dive.
this time submarine is most modern system is depth is 300 to 450 meters,high pressure air is 15 bar is tank air valve.
submarine is basic of the effective volume of all the submarine surfaced condition,submarine minus to the free water flood is equal to the fully pressure hull,submarine is the surfaced condition.
What two factors determine how much potential energy an object has?
Answer:
The mass of the object and its height in the gravitational field of the Earth.
Explanation:
If we are talking about gravitational potential energy which is defined as:
[tex]U=m\,*\,g\,*\,h[/tex]
being "m" the object's mass, "g" the acceleration due to gravity, and "h" the height at which the object is located relative to the conventionally picked level for zero of potential energy.
As long as the value of "g" is constant, the only two variables that determine the gravitational potential energy are the mass (m) of the object and its relative height (h).
Answer:
The objects weight and height above Earth's surface
Explanation:
K12 :)
A group of Advanced Open Water Divers plans to make two dives. The first dive is on a reef in 90 feet of water for 20 minutes. The group then remains on the surface for 1 hour. The second dive is on a wreck in 60 feet of water, with a planned bottom time of 30 minutes. What will be the ending pressure group after the second dive
Answer:
The ending pressure is R.
Explanation:
This is Recreational scuba diving (R). According to standards, this diving has prescribed depth limit of 130 ft. This means that the limit must include a depth that is not greater than 130 ft while using only compressed air and not even requiring a decompression stop.
Now, from the question, we can see that that there was a prescribed limit of 60ft of water with a planned bottom time of 30 minutes.
Thus, the ending pressure is R.
Which of the following is the correct equation to calculate electrical energy? P = I/V V = P × I P = I × V E = P × t
You haven't told us what any of those letters represents.
I'm going to assume that ...
-- ' P ' = power
-- ' I ' = circuit current
-- ' V ' = circuit voltage
-- ' E ' = energy
-- ' t ' = time.
Now I'm ready to answer the question that I just invented.
P = I / V
V = P x I
Both of these are false statements, and can't be used to calculate anything.
P = I x V is the correct equation to calculate electrical power.
E = P x t is the correct equation to calculate electrical energy.
Two 110 kg bumper cars are moving toward each other in opposite directions. Car A is moving at 8 m/s and Car Z at −10 m/s when they collide head–on. If the resulting velocity of Car A after the collision is −10 m/s, what is the velocity of Car Z after the collision? 10 m/s −8 m/s 8 m/s 10 m/s-
Answer:
it will be 8ms-1
Explanation:
MaUa+MbUb=MaVa+MbVb
Because the neutron has no charge, its mass must be found in some way other than by using a mass spectrometer. When a neutron and a proton meet (assume both to be almost stationary), they combine and form a deuteron, emitting a gamma ray whose energy is 2.2233 MeV. The masses of the proton and the deuteron are 1.007 276 467 u and 2.013 553 212 u, respectively. Based on this data, what is the mass of the neutron
Answer:
Explanation:
Energy of gamma ray = 2.2233 MeV
Let mass of neutron be n amu
mass defect of deuteron = 2.013553212 - ( 1.007 276 467 + n ) u .
in terms of energy this mass defect will be equal to energy of gamma ray
1 amu = 931 MeV
931 [ 2.013553212 - ( 1.007 276 467 + n ) ] = 2.2233
( 1.007 276 467 + n ) - 2.013553212 = .00238807733
n = 1.008664822 amu
so mass of neutron = 1.008664822 amu
The distance from the Earth to the Sun equals 1 AU. Neptune is 30 AU from the Sun. How far is Neptune from the Earth? AU
Answer:
The answer is 29 AU
Hoped I helped
mark me as brainliest
Answer:
29
Explanation:
THE LENGTH OF A PENDULUM IS (1.5±0.01)m AND THE ACCELERATION DUE TO GRAVITY IS TAKEN AS (9.8±0.1)ms-² calculate the time period of the pendulum with uncertainty in it
Answer:
2.4583 ± 0.0207 seconds
Explanation:
The time period of a pendulum is approximately given by the formula ...
T = 2π√(L/g)
The maximum period will be achieved when length is longest and gravity is smallest:
Tmax = 2π√(1.51/9.7) ≈ 2.47903 . . . seconds
The minimum period will be achieved for the opposite conditions: minimum length and maximum gravity:
Tmin = 2π√(1.49/9.9) ≈ 2.43756 . . . seconds
If we want to express the uncertainty using a symmetrical range, we need to find half their sum and half their difference.
T = (2.47903 +2.43756)/2 ± (2.47903 -2.43756)/2
T ≈ 2.4583 ± 0.0207 . . . seconds
__
We have about 2+ significant digits in the given parameters, so the time might be rounded to 2.46±0.02 seconds.
1. Determina el momento que produce una fuerza de 7 N tangente a una rueda de un metro de diámetro, sabiendo que el punto de aplicación es el mismo borde de dicha rueda provocando un impulso en el sentido de las agujas del reloj. Solución:
Answer:
τ= F r into the blade
Explanation:
The moment of a force is defined by
τ = F x r
where the bold indicates vectors
Let us write in the expression in magnitude
τ = F r sin θ
in our case the force is tangent to the wheel therefore the angle between F and the radius is 90º, and the sin 90 = 1
τ= F r
The direction of τ can be used by the rule of the right hand, the fingers curve in the direction of the torque when advancing from the force to the radius and the thumb points in the direction of the torque.
In this case, for a clockwise rotation, the fingers are curved in the direction and the thumb points into the blade, this is the direction of the τ.
TRASLATE
El momento de una fura es definido por
τ = F x r
donde la negrillas indican vectores
Escribamos en ta expresión en magnitud
τ = F r sin θ
en nuestro caso la fuerza es tangente a la rueda por lo tanto el angulo entre F y el radios es 90º, y el sin 90=1
τ = F r
la dirección de tau la podemos usar la regla de la mano derecha, los dedos curva en la dirección del torque al avanzar dese la fuerza al radio y el pulgar apunta en la dirección del torque.
En este caso para un giro en sentido horario los dedos se curvan ente sentido y el pulgar apunta hacia dentro de lla hoja, esta es la dirección del troque
I need help. can I get some
Explanation:
a) Acceleration is the slope of the velocity vs time graph. When velocity vs time is a straight line, that means the acceleration is a constant. F = ma, so the resultant force is also constant.
b) As air resistance increases, the acceleration begins to decrease.
c) A falling object stops accelerating when it reaches terminal velocity.
d) F = ma, so when the acceleration is 0, the resultant force is also 0.
An average skater averages 11 m/s over the first 5 seconds of a race. find the average speed required over next 10 seconds to average 12 m/s overall.
Answer:
usa
Explanation:
A metal disk lies in the xy-plane, centered about the origin, and rotates with a constant angular velocity about the z-axis. There is a uniform 0.0314 T magnetic field parallel to the z-axis. The radius of the disk is 1.56 m. At what rate is the disk turning if an E of 3.86 V develops between the center of the disk and a point on its rim
Answer:
w = -101 rad / s
Explanation:
For this exercise we will use Faraday's law
E = - dФ / dt
where the magnetic flux is
Ф = B. A = B A cos θ
In this case, the angle between the magnetic field and the normal to the disk is zero, cos 0 = 1, they indicate that the field is constant, let's find the area
The area rotated by the disk is
A = ½ r s
if we express the angles in radians
θ = s / r
s = r θ
where is the arc supported
A = ½ r (r θ)
let us substitute in the Faraday equation
E = - d (B ½ r² θ) / dt
E = - ½ B r² dθ/dt
the definition of angular velocity is
w = dθ/dt
E = - ½ B r² w
w = - 2E / B r²
let's calculate
w = - 2 3.86 / (0.0314 1.56²)
w = -101 rad / s
A wave is represented by the equation y = 0.20 sin [ 0.4π (x – 60t)], where x and y are in cm and t is in s. The velocity of the wave is...
Answer:
v = 60 m/s
Explanation:
It is given that,
A wave is represented by the equation :
[tex]y=0.2\sin [0.4\pi (x-60)t][/tex]
We need to find the velocity of the wave
The general equation of a wave is given by :
[tex]y=A\sin (kx-\omega t)[/tex] ....(1)
Equation (1) can be written as :
[tex]y=0.2\sin (0.4\pi x-24\pi t)[/tex] ...(2)
If we compare equation (1) and (2) we get :
[tex]k=0.4\pi[/tex]
[tex]\omega=24\pi[/tex]
The velocity of a wave is given by :
[tex]v=\dfrac{\omega}{k}\\\\v=\dfrac{24\pi}{0.4\pi}\\\\v=60\ m/s[/tex]
So, the velocity of the wave is 60 m/s.
What is a hypothesis?
A. A piece of information gathered during an experiment
OB. A source that summarizes a primary source
O C. Something that a scientist intentionally changes during an
experiment
O D. An educated guess about the outcome of an experiment
Answer:
D!!!!!
Explanation:
A hypothesis is a supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation.
Answer:
D. An educated guess about the outcome of an experiment.
Explanation:
Hypothesis is an educated guess about the outcome of an experiment.
Hope this helps ;) ❤❤❤
3) A charged particle is moving with velocity of V in a magnetic field of B, which one of the followings is correct: A) The direction of force F on the charge is parallel to magnetic field B B) The direction of force F on the charge is parallel to velocity direction V C) The force is maximized when velocity direction and magnetic field are parallel D) The force F is perpendicular (normal) to both velocity V and magnetic field B E) The direction of force on positive charge or negative charge would be the same
Answer:
D) The force F is perpendicular (normal) to both velocity V and magnetic field B.
Explanation:
When a charged particle enters a magnetic field, it experiences a force which changes its direction of travel. The direction of motion of the charged particle, the magnetic field direction, and the direction of the force, are all perpendicular to one another. According to Lorentz right hand rule, hold the right hand parallel to the ground, with the palm facing up, and the thumb held out at right angle to the other fingers. If the direction of the other fingers represents the magnetic field line and direction, and the thumb represents the direction of motion of a positively charged particle, then, the palm will push up in the direction of the force. For a negatively charged particle, the force will push down in the direction of the back of the hand.
Pls help! If you know the answer
Answer:
-40
Explanation:
-40= (9/5)(-40) + 32
=-72 + 32
-40=-40
A parallel-plate capacitor has square plates that are 7.40 cm on each side and 3.20 mm apart. The space between the plates is completely filled with two square slabs of dielectric, each 7.40 cm on a side and 1.60 mm thick. One slab is Pyrex glass and the other slab is polystyrene. If the potential difference between the plates is 84.0 V, find how much electrical energy (in nJ) can be stored in this capacitor.
Answer:
The energy that can be stored in the capacitor is 239 nJ
Explanation:
We first calculate the capacitance of each material. Let C₁ be the capacitance of pyrex glass and C₂ be the capacitance of polystyrene.
C₁ = κ₁ε₀A/d where κ₁ = dielectric constant of pyrex glass = 5, A = area of plates = L² where L = length of square plate = 7.40 cm = 7.40 × 10⁻² m and d = thickness of pyrex slab = 1.60 mm = 1.60 × 10⁻³ m and ε₀ = permittivity of free space = 8.854 × 10⁻¹² F/m
C₁ = κ₁ε₀A/d = κ₁ε₀L²/d = 5 × 8.854 × 10⁻¹² F/m × (7.40 × 10⁻² m)²/1.60 × 10⁻³ m = 2424.2252/1.60 × 10⁻¹¹ F = 1515.14 × 10⁻¹¹ F = 15.2 × 10⁻⁹ F = 15.2 nF
C₂ = κ₂ε₀A/d where κ₂ = dielectric constant of polystyrene = 3, A = area of plates = L² where L = length of square plate = 7.40 cm = 7.40 × 10⁻² m and d = thickness of polystyrene slab = 1.60 mm = 1.60 × 10⁻³ m and ε₀ = permittivity of free space = 8.854 × 10⁻¹² F/m
C₁ = κ₁ε₀A/d = κ₁ε₀L²/d = 3 × 8.854 × 10⁻¹² F/m × (7.40 × 10⁻² m)²/1.60 × 10⁻³ m = 1454.5351/1.60 × 10⁻¹¹ F = 909.08 × 10⁻¹¹ F = 9.09 × 10⁻⁹ F = 9.09 nF
Since the capacitors are in series, we find their effective capacitance C from
1/C = 1/C₁ + 1/C₂
C = C₁C₂/(C₁ + C₂)
= 15.2 × 10⁻⁹ F × 9.09 × 10⁻⁹ F/(15.2 × 10⁻⁹ F + 9.09 × 10⁻⁹ F)
= 138.168 × 10⁻¹⁸/24.29 × 10⁻⁹ F
= 5.69 × 10⁻⁹ F
The amount of electrical energy stored in a capacitor is given by W = 1/2CV² where C = capacitance and v = voltage applied. Now C = 5.69 × 10⁻⁹ F and V = 84.0 V for this capacitor
So W = 1/2 × 5.69 × 10⁻⁹ F × 84.0 V
= 238.98 × 10⁻⁹ J
≅ 239 × 10⁻⁹ J
= 239 nJ
So the energy that can be stored in the capacitor is 239 nJ
a. Define Valency. b. Write the symbol and valency of the following : (i) Oxygen (ii) potassium 7. a. Magnesium burns in Oxygen to form Magnesium Oxide. a) Name the reactants b) Name the Products c) Write the word equation for the above reaction.
Answer:
Oxygen-Symbol-O Potassium Symbol-K
A) Valency is the combining capacity of any element. Valence electrons refers to the electrons found in the outermost shell of the atom of the element.
B) Symbol and valency:
Oxygen(O) = (At. no. 8) = -2(Valency)Potassium(K) = (At. no. = 19) = +1(Valency)C) The reaction would be:
[tex] \large{ \boxed{ \rm{2Mg + O_2 \longrightarrow \: 2MgO}}}[/tex]
Reactants = Magnesium and Oxygen Products = Magnesium oxideWord equation:[tex] \large{ \boxed{ \rm{Magnesium + Oxygen \longrightarrow Magnesium oxide.
}}}[/tex]
━━━━━━━━━━━━━━━━━━━━
a object 1.5cm high produces a real image 2cm high. placed at a distance of 20cm
from a concave mirror calculate: [a] the position of the image [b] focal lenght of the concave mirror
Answer:
a. 26.7 cm. b. 11.4 cm.
Explanation:
a. We know h'/h = d'/d where h' = image height = + 2 cm (since it is a real image), h = object height = + 1.5 cm, d' = image distance from mirror and d = object distance from mirror = 20 cm
So, from h'/h = d'/d
d = h'd/h
= 2 cm × 20 cm/1.5 cm
= 40/1.5 cm
= 26.67 cm
≅ 26.7 cm
The position of the image is 26.7 cm from the mirror
b. Using the mirror formula
1/d + 1/d' = 1/f where d = object distance from mirror = + 20 cm, d' = image distance from mirror = + 26.7 cm (its positive since its a real image) and f = focal length of mirror.
So, 1/d + 1/d' = 1/f
⇒ f = dd'/(d + d')
= 20 cm × 26.7 cm/(20 cm + 26.7 cm)
= 534/46.7
= 11.43 cm
≅ 11.4 cm
The focal length of the mirror is 11.4 cm
