The optics of your visual system have a total refractive power of about +60 D—about +20 D from the lens in your eye and +40 D from the curved shape of your cornea. Surgical procedures to correct vision generally do not work on the lens; they work to reshape the cornea. In the most common procedure, a laser is used to remove tissue from the center of the cornea, reducing its curvature. This change in shape can correct certain kinds of vision problems.
The length of your eye decreases slightly as you age, making the lens a bit closer to the retina. Suppose a man had his vision surgically corrected at age 30. At age 70, once his eyes had decreased slightly in length, he would be:________.
A. Nearsighted.
B. Farsighted.
C. Neither nearsighted nor farsighted.

Answer:

Farsighted

Explanation:

Farsightedness also known as hypermetropia is caused by the eye being too short(the eye shortens with advancing age) or the crystalline lines not being sufficiently convergent.

A farsighted person can see far objects but can not see nearby objects. His near point is now farther than the 25 cm near point of a normal eye. Images are formed some distance behind the retina.

This eye defect is corrected by the use of a converging lens to reduce the divergence of the rays entering the eye from an object.

What is happening in the graph shown below?


A.
The object moves away from the origin at a speed of 3 m/s, stands still 6 m away from the origin for 3 seconds, then moves toward the origin at a speed of 2 m/s.
B.
The object moves toward the origin at a speed of 3 m/s, stands still 6 m away from the origin for 3 seconds, then moves away from the origin at a speed of 2 m/s.
C.
The object moves toward the origin at a speed of 6 m/s, stands still 6 m away from the origin for 3 seconds, then moves away from the origin at a speed of 8 m/s.
D.
The object moves away from the origin at a speed of 6 m/s, stands still 6 m away from the origin for 3 seconds, then moves toward the origin at a speed of 8 m/s.

The gravitational force between two objects with masses 1kg and 28kg separated by a distance 7m is ____________10-11 N.


a.
3.81

b.
26.68

c.
9151.24

d.
1307.32
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