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KIM [24]
3 years ago
10

A physicist's right eye is presbyopic (i.e., farsighted). This eye can see clearly only beyond a distance of 97 cm, which makes

it difficult for the physicist to read books and journals. Find the focal length and power of a lens that will correct this presbyopia for a reading distance of 25 cm, when worn 2 cm in front of the eye
Physics
1 answer:
Ivan3 years ago
5 0

Answer:

f = 19,877 cm   and  P = 5D

Explanation:

This is a lens focal length exercise, which must be solved with the optical constructor equation

        1 / f = 1 / p + 1 / q

where f is the focal length, p is the distance to the object and q is the distance to the image.

In this case the object is placed p = 25 cm from the eye, to be able to see it clearly the image must be at q = 97 cm from the eye

let's calculate

        1 / f = 1/97 + 1/25

        1 / f = 0.05

        f = 19,877 cm

the power of a lens is defined by the inverse of the focal length in meters

         P = 1 / f

         P = 1 / 19,877 10-2

         P = 5D

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Answer:A) Risk(R)= $1000

B) There is justification for spending an additional cost of $100 to prevent a corrosion whose consequence in monetary terms is $1000

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Mathematically, R=P ×C

10 out of 1000 carbon-steal products failed

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The consequence of failure by corrosion given in monetary term =$100,000

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4 0
3 years ago
Find an expression for the electric field e⃗ at the center of the semicircle. hint: a small piece of arc length δs spans a small
ahrayia [7]
Let l = Q/L = linear charge density. The semi-circle has a length L which is half the circumference of the circle. So w can relate the radius of the circle to L by 

<span>C = 2L = 2*pi*R ---> R = L/pi </span>

<span>Now define the center of the semi-circle as the origin of coordinates and define a as the angle between R and the x-axis. </span>

<span>we can define a small charge dq as </span>

<span>dq = l*ds = l*R*da </span>

<span>So the electric field can be written as: </span>

<span>dE =kdq*(cos(a)/R^2 I_hat + sin(a)/R^2 j_hat) </span>

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8 0
3 years ago
Hummingbirds may seem fragile, but their wings are capable of sustaining very large forces and accelerations. (Figure 1) shows d
gulaghasi [49]

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5 0
2 years ago
What is the magnitude of the torque about his shoulder if he holds his arm straight out to his side, parallel to the floor
const2013 [10]

Complete Question

An athlete at the gym holds a 3.0 kg steel ball in his hand. His arm is 70 cm long and has a mass of 4.0 kg. Assume, a bit unrealistically, that the athlete's arm is uniform.

What is the magnitude of the torque about his shoulder if he holds his arm straight out to his side, parallel to the floor? Include the torque due to the steel ball, as well as the torque due to the arm's weight.

Answer:

The torque is  \tau = 34.3 \  N\cdot m

Explanation:

From the question we are told that

   The mass of the steel ball is  m  =  3.0 \  kg

    The length of arm is  l =  70 \ cm  = 0.7 \  m

    The mass of the arm is m_a  = 4.0 \  kg

Given that the arm of the athlete is uniform them the distance from the shoulder to the center of gravity of the arm is mathematically represented as

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=>    r = \frac{ 0.7}{2}  

=>    r = 0.35 \ m  

Generally the magnitude of torque about the athlete shoulder is mathematically represented as

      \tau =  m_a * g * r  + m * g *  L

=>    \tau =  4 * 9.8 * 0.35 + 3 * 9.8 *  0.70

=>    \tau = 34.3 \  N\cdot m

5 0
2 years ago
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baherus [9]

Answer:

\theta_c = 36.78^o

Explanation:

The relationship between the refractive index and the critical angle is given as follows:

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where,

η = refractive index = 1.67

θc = critical angle =?

Therefore,

\theta_c = Sin^{-1}(\frac{1}{1.67} )

\theta_c = 36.78^o

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3 years ago
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