If a man with
with long-sighted eye want to
a' text book, what shoðld be the distance between
book and the lens? Give reason​

Answers

Answer 1
Lots of factors play a role. Firstly if he is presbyopic he won't be able to read without specs at normal reading distances. Many years ago a chap by the name of Donders published a table which shows a linear relationship between age and ability to focus. The ready made reader market relies on his findings to suggest the power you need for reading at different ages. Secondly if he is far sighted (needing correction at distance to see clearly) it will also influence his ability to see close. For example +3.00D distance Rx at an age of 40 years will be very different than the same prescription at age 20 years due to his ability to accommodate. My suggestion is to have comprehensive eye exam to find out what you need at the specific working distance (computer or laptop or book reading all have different reading distances).

Related Questions

A boat has a porthole window, of area 0.00849 m^2, 6.25 m below the surface. The density of sea water is 1027 kg/m^3. The air inside the boat is at 1 atm. What is the net force on the window?

Answers

Answer:

[tex]325.65\ \text{N}[/tex] outward.

Explanation:

[tex]\rho[/tex] = Density of water = [tex]1027\ \text{kg/m}^3[/tex]

g = Acceleration due to gravity = [tex]9.81\ \text{m/s}^2[/tex]

h = Height of the water = 6.25 m

A = Area of the window = [tex]0.00849\ \text{m}^2[/tex]

[tex]P_i[/tex] = Internal pressure of the boat = [tex]1\ \text{atm}=101325\ \text{Pa}[/tex]

Pressure by the water on the window

[tex]P=\rho gh\\\Rightarrow P=1027\times 9.81\times 6.25\\\Rightarrow P=62967.9375\ \text{Pa}[/tex]

Net pressure on the window

[tex]P_n=P-P_i=62967.9375-101325=-38357.0625\ \text{Pa}[/tex]

Force is given by

[tex]F=P_nA\\\Rightarrow F=-38357.0625\times 0.00849\\\Rightarrow F=-325.651460625\ \text{N}[/tex]

Net force on the window is [tex]325.65\ \text{N}[/tex] outward.

Answer: 534.6 N

Explanation:

This answer works for Acellus!

Robert hook used an early microscope to observed a cork sample. How did this help contribute to cell theory?

Answers

Answer:

Robert Hooke used an early microscope to observe a cork sample. How did this help contribute to cell theory? It helped to show that cells contain water. ... It helped to show that some cells are visible to the naked eye.

Explanation:

If your teacher checks if it was copied just put it in your on words

PLS ANSWER FAST WILL GIVE BRAINLY TIMED TEST


use the equation solving a= F divided by M


Also use metres per second squared [m/s2]



A loaded coal wagon with a total mass of 20, 000 kg is pushed by a force of 300,000 N. What was the wagon's acceleration?

Answers

a=F/m
a=(3000000)/(20000)
a=15 m/s^2

Hell it’s due soon??

Answers

Explanation:

don't know don't know don't know

Outward.................

Need help ASAP
Thanks + BRAINLIST only for correct answer

1.Cell phones convert sound waves into______waves.
-light waves
-sound waves
-radio waves

2.Electromagnetic waves used in cell phone communications are called?
-microwave
-radio wave
-infrared
-all of the above

3.To send out a radio signal far and wide...it is called?
-broadcast
-casting
-antenna

Answers

Answer:

answer my question

Explanation:

Mhm yeah correct I think yeah yeah lol

What is the netforce?

Answers

Answer:

6 Newtons to the left.

Explanation:

We can convert  this into a generic algebra equation by giving directions positive and negative values.

The 6 will be positive, and the 10 and 2 will be negative.

Add 10 and 2 to have 12.

6-12 = -6.

Therefore you have 6 newtons to the left (negative).

Take the force towards the right as positive (+6N) and towards the left as negative (-12N)
Add both as net force is the sum of all forces acting on an object
6N+(-12N)= -6N

The odometer of a car reads 57321 km when the clock shows the time 8.30 am. What is the distance moved by the car, if at 8.50 am, the odometer reading has changed to 57336.0 km? Calculate the speed of the car in km/min during this time.

Answers

Answer:

0.75km/min

Explanation:

I haven't learnt physics at all but I'll try

57336 - 57321 = 15km (Difference)

8.50 am - 8.30 am = 20 minutes (Difference)

If the car odometer adds up 15km every 20 minutes...

20 mins = 15km

1 min = 15 ÷ 20 = 0.75km

A raindrop falls from a cloud 100 m above the ground. Neglect air resistance. What is
the speed of the raindrop when it hits the ground? Is this a reasonable number? Explain.

Answers

Answer:

Explanation:

Use the kinematic equation

[tex]V^2=V^2_i+2a(x_f-x_i)[/tex]

The initial velocity was given from the word "falls." Acceleration due to gravity is 9.8 m/s^2.

[tex]V^2=0^2+200(9.8)[/tex]

[tex]V=\sqrt{1960} =44.27m/s[/tex]

A raindrop falls from a cloud 100 m above the ground. Neglect air resistance. The speed of the raindrop when it hits the ground would be 44.27 meters/ second.

What is mechanical energy?

The sum of all the energy in motion (total kinetic energy) and all the energy that is stored in the system (total potential energy) is known as mechanical energy.

As given in the problem A raindrop falls from a cloud 100 m above the ground. Neglect air resistance, then we have to find out the speed of the raindrop when it hits the ground,

The speed of the raindrop  = √(2gh)

                                             =√(2*9.8*100)

                                              =44.27 meters/seconds

Thus, if a raindrop falls from a cloud 100 m above the ground. Neglect air resistance. the speed of the raindrop when it hits the ground would be 44.27 meters/ second.

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John slides down a hill at a 4 m height initially at rest. If all energy is conserved and friction is excluded, what is John's velocity at the bottom of the ramp?

Answers

The velocity at the bottom : v = 8.85 m/s

Further explanation

Given

height of the hill = 4 m

Required

The velocity at the bottom

Solution

The law of conservation energy :

ME₁=ME₂

(PE+KE)₁ = (PE+KE)₂

initially at rest⇒vo=0⇒KE₁=0

At the bottom⇒h=0⇒PE₂=0

So the equation becomes :

PE₁=KE₂

mgh=1/2.mv²

gh = 1/2v²

[tex]\tt v=\sqrt{2gh}[/tex]

v = √2x9.8x4

v = 8.85 m/s

Explain how smoking damages the respiratory system and name two conditions that can develop when a person smokes. ribe the location and importance of cilia and mucus in the respiratory system.

Answers

Answer:

Smoking damages the respiratory system by irritating the trachea and larynx due to the toxic chemicals and by causing swelling and narrowing of the airways and excess mucus in the lung passages. Two conditions that can develop when a person smokes is breathlessness and reduced lung function.

Explanation:

Smoking causes damages to the respiratory system by narrowing the airways and filling an excess of mucus in the lungs. It is a bad habit that may cause emphysema and chronic bronchitis.

Cigarettes contain more than 500 chemical substances in addition to nicotine, an addictive substance found in tobacco.

Cilia are hair-like projections localized in the airways that act to eliminate mucus and foreign (potentially harmful) matter.

The toxic compounds contained in cigarettes can paralyze the cilia in the airways and destroy them.

Smoking may produce:

The irritation and inflammation of the components of the respiratory system (e.g., trachea, larynx, lungs, etc)BreathlessnessExcess of mucous secretion in the lungs.Irreversible damage in the small air sacs of the lungs.

In consequence, smoking is associated with chronic obstructive pulmonary diseases, including chronic bronchitis or emphysema.

In conclusion, smoking causes damages to the respiratory system by narrowing the airways and filling an excess of mucus in the lungs. It is a bad habit that may cause emphysema and chronic bronchitis.

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How much force must be applied to a 4 kg to get it to accelerate at 3
m/s^2?

Answers

Answer:

12 g i think

Explanation:

brainliest pls

Two identical conducting spheres are charged with a net charge of +5.0 q on the first sphere and a net charge of −8.0 q on the second sphere. The spheres are brought together, allowed to touch, and then separated. What is the net charge on each sphere now?

Answers

Answer:

The net charge on each sphere is -1.5 q

Explanation:

Conductors are materials that allow the electrons which are the carriers of the charges to move between them, and when two conductors come in contact, the available charge is shared by the two conductors and the resultant like charges will spread on the surface of the conductor due to the repellent effect between similar charges such that if the conductors are identical, the resultant charge becomes evenly shared by the conductors when they become separated again

The given parameters of the conducting spheres meant to touch are;

The net charge on the first sphere, Q₁ = +5.0 q

The net charge on the second sphere, Q₂ = -8.0 q

The net charge on each sphere after touching and then separated, 'Q', is given as follows;

[tex]Q = \dfrac{Q_1 + Q_2}{2}[/tex]

Therefore, by substituting the known values of the variables, we have;

[tex]Q = \dfrac{5 \ q+ (-8 \ q)}{2} = -\dfrac{3 \ q}{2} = -1.5 \ q[/tex]

The net charge on each sphere, Q = -1.5 q.

The net charge on each sphere after spheres are brought together, allowed to touch is -1.5 q

What is charge?

Conductors are materials that allow the electrons which are the carriers of the charges to move between them, and when two conductors come in contact, the available charge is shared by the two conductors and the resultant like charges will spread on the surface of the conductor due to the repellent effect between similar charges such that if the conductors are identical, the resultant charge becomes evenly shared by the conductors when they become separated again

The given parameters of the conducting spheres meant to touch are;

The net charge on the first sphere, Q₁ = +5.0 q

The net charge on the second sphere, Q₂ = -8.0 q

The net charge on each sphere after touching and then separated, 'Q', is given as follows;

[tex]Q=\dfrac{Q_1+Q_2}{2}[/tex]

Therefore, by substituting the known values of the variables, we have;

[tex]\dfrac{5q+(-8q)}{2}=-1.5q[/tex]

Hence the net charge on each sphere after spheres are brought together, allowed to touch is -1.5 q

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Sometimes, a crackling sound is heard while taking off a sweater during winters. Explain

Answers

Answer:

it is somewhat frozen

Explanation:

Complete play the table by writing the location orientation size and type of image formed by the lenses below.


Please help me guyss!! :(​

Answers

Answ

Explanation:

HOPE IT HELPS..

The image formed by the location of object is beyond 2F the image by convex lenses is between F and 2F and is inverted, smaller and and real image. If it is at 2F, the image is inverted with the same size and real.

What is a convex lens ?

A convex lens is a type of lens that is projected outwards and shows the real image of an object.  Whereas a concave lens is curved inwards and shows virtual image of objects.

The image formed at by the location of convex lenses beyond 2F is inverted, smaller and and real image. If it is at 2F, the image is inverted with the same size and real. If the lens is placed between F and 2F the image formed is beyond 2F and it will be inverted, enlarged and real.

If the object is at F , no image will be formed. If it at between F and the lens, then the image forms beyond 2 F which is upright, enlarged and virtual.

The object be at any position with respect to the focal length of lens, the image formed by a concave lens is between F and the lens and upright, small and virtual.

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Suman with a mass of 45kg climbs in 3m heigh ladder in 10 seconds. Calculate her power. Plz help me​

Answers

Answer:

work done=fdcosø

f=mg=450N

d=+3m

ø=180

450×3×cos(180°) power=work done/

time taken

1350×-1 p=135watts

Which form of electromagnetic radiation with a relatively high amount of energy is used to sanitize lab goggles?

Answers

Answer:

Gamma radiation.

Explanation:

Electromagnetic waves are waves produced with respect to the interaction of electric field and magnetic field. They can be arranged with respect to their increasing or decreasing wavelength to form a pattern called electromagnetic spectrum.

Gamma radiation can be used for sterilization purpose due to the fact that it has a relatively high amount of energy, and do not produce any characteristic radiation.

Please Help!! This is for my Science Assignment but I dont even know how to do the last part (d; Find frictional force)

Answers

Answer:

I known this much much except c and d. Hope this helps, thank you !!

A 2500-kg car is being pushed up a hill at an angle of 35 degrees. Determine the gravitational

force pulling down on the car if it is accelerating up the hill at a rate of 5 m/s/s.

Answers

Answer:

The force that pulls the car down is Wₓ = 14052.6 N and the one that pushes the car up is F = 26552.6 N

Explanation:

For this exercise we will use Newton's second law, let's set a reference system where the x axis is parallel to the plane, in the adjoint we can see the forces in the system.

           sin  35 = Wₓ / W

            cos 35 = W_y / W

            Wₓ = W sin 35

            W_y = W cos 35

            Wₓ = 2500 9.8 sin 35

             Wₓ = 14052.6 N

let's write the equations for each axis

and

Y axis  

       N-W_y = 0

       N = W_y

X axis  

       F -Wₓ = m a

       F = Wₓ + m a = mg sin 35 + m a

       F = m (a + g sin 35)

   

let's calculate

       F = 2500 (5 + 9.8 sin 35)

       F = 26552.6 N

The force that pulls the car down is Wₓ = 14052.6 N and the one that pushes the car up is F = 26552.6 N

There is a current of 2.95 A in one of the copper wires for 60 seconds. Calculate the charge flow through the wire.

Answers

Answer:

177 coulomb

Explanation:

Given data

I=2.95A

T=60

The relationship between current I and quantity of charge Q.

Q=IT

Substitute

Q=2.95*60

Q=177 coulomb

Which examples best demonstrate likely tasks for Legal Services workers? Check all that apply.

Cisco inspects an office building to make sure it meets fire safety regulations.
Gina gathers information about a court case.
Saul oversees inmates at a correctional facility.
Hana interviews and advises a person who has been accused of a crime.
Pamela pursues and arrests a person suspected of a crime.
Dewayne creates the paperwork for a business contract.

Answers

Answer:

b. d. f.

Explanation:

Got it right on Edge

Answer:

2. Gina gathers information about a court case.

4. Hana interviews and advises a person who has been accused of a crime.

6. Dewayne creates the paperwork for a business contract.

Determine the momentum of a system that consists of two objects. One object, m1, has a mass of 6 kg and a velocity of 13 m/s towards the east and a second object, m2, has a mass of 14 kg and a velocity of 7 m/s in that same direction.

Answers

Momentum = (mass) x (velocity)

Momentum m₁  =  (6 kg) x (13 m/s east)  =  78 kg-m/s east

Momentum m₂  =  (14 kg) x (7 m/s east)  =  98 kg-m/s east

Since they're both in exactly the same direction you can simply addum up to get their total momentum.  It's 176 kg-m/s east .

The  momentum of a system that consists of two objects should be 176 kg m/s on east hand side.

Calculation of the momentum:

Since we know that

Momentum = (mass) x (velocity)

So,

Momentum m₁  =  (6 kg) x (13 m/s east)  =  78 kg-m/s east

Momentum m₂  =  (14 kg) x (7 m/s east)  =  98 kg-m/s east

Since they are on same direction so the total momentum should be

= 78 + 98

= 176 kg-m/s east

hence, The  momentum of a system that consists of two objects should be 176 kg m/s on east hand side.

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