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natali 33 [55]
3 years ago
6

A farsighted boy has a near point at 2.3 m and requires eyeglasses to correct his vision. Corrective lenses are available in inc

rements in power of 0.25 diopters. The eyeglasses should have lenses of the lowest power for which the near point is no further than 25 cm. The correct choice of lens power for eyeglasses, in diopters, is:
Physics
1 answer:
tino4ka555 [31]3 years ago
5 0

Answer:

P = 3.5 D

Explanation:

As we know that convex lens is to be used to make the near point of eye to be correct

So we will have

\frac{1}{d_i} + \frac{1}{d_o} = \frac{1}{f}

here we have

d_i = 2.3 m = 230 cm

d_o = 25 cm

now plug in all values into the formula

-\frac{1}{230} + \frac{1}{25} = \frac{1}{f}

f = 28 cm

now for power of lens

P = \frac{1}{f}

P = \frac{1}{0.28} = 3.5 D

so the power in dioptre is

P = 3.5 D

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Tires of a Bigfoot truck has a diameter of 2.2 m. If it rotates 60 revolutions find distance travel on the road.
Firlakuza [10]

Answer:

s = 414.7 m\\

Explanation:

The relationship between the linear distance covered by an object and its angular displacement is given by the following formula:

s = rθ

where,

s = distance traveled on road = ?

r  radius of tires = diameter/2 = 2.2 m/2 = 1.1 m

θ = angular displacement = (60 rev)(2π rad/1 rev) = 377 rad

Therefore,

s = (1.1 m)(377 rad)\\s = 414.7 m

8 0
3 years ago
The air in a room has a pressure of 1 atm, a dry-bulb temperature of 24°C, and a wet-bulb temperature of 17°C. Using the psychro
Licemer1 [7]

Answer:

Given that

Dry-bulb temperature(T) =24°C

Wet-bulb temperature(Tw) = 17°C

Pressure ,P = 1 atm

As we know that  psychrometric chart are drawn at constant pressure.

From the diagram

ω= specific humidity

Lets take these two lines   Dry-bulb temperature(T) line and Wet-bulb temperature(Tw) cut at point P

From chart at point P

a)

Specific humidity,ω = 0.00922 kg/kg

b)

The enthalpy ( h)

h=47.59 KJ/kg

c)

The relative humidity, RH

RH= 49.58 %

d)

Specific volume ,

v= 0.853 m³/kg

5 0
3 years ago
three girls were pushing the same car with a net force of 450 N [N48°E]. Two of the girls were pushing with forces of 310 N [N25
ElenaW [278]

The net force is the vector

∑ F = (450 N) (cos(42°) i + sin(42°) j)

and two of the forces provided by the girls are

F₁ = (310 N) (cos(115°) i + sin(115°) j)

F₂ = (250 N) (cos(285°) i + sin(285°) j)

Then the force provided by the third girl is the vector

F₃ = ∑ F - F₁ - F₂

F₃ = ((450 N) cos(42°) - (310 N) cos(115°) - (250 N) cos(285°)) i

… … … + ((450 N) sin(42°) - (310 N) sin(115°) - (250 N) sin(285°)) j

F₃ ≈ (400.722 N) i + (261.635 N) j

So, the third girl provided a force of magnitude

||F₃|| = √((400.722 N)² + (261.635 N)²) ≈ 478.572 N ≈ 480 N

pointing in a direction

arctan((261.635 N)/(400.722 N)) ≈ 33.1409° ≈ 33°

relative to East which refers to 0°; that is, 33° N of E or E33°N. Since the other forces are given relative to North or South, we can write this direction as N57°E.

So, the third girl pushed with force 480 N [N57°E].

5 0
3 years ago
What is the energy due to compressing a spring
Westkost [7]

Answer: Elastic Potential Energy

Explanation: Energy present on compressed strings is called Elastic Potential Energy.

8 0
3 years ago
The pressure of liquid varies as per<br>its depth​
Slav-nsk [51]

Answer:

Yes.

Explanation:

The pressure varies as per the depth of the container

4 0
3 years ago
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