Presbyopia is the tendency to gradually become far-sighted (hyperopic) as you age. If you have normal vision when you are young, you have a near point of 25 cm. A. If the distance between your eye's lens and retina is 1.71 cm, what is the focal length of your eye's lens when you look at an object at your near point? f = cm B. As you get older, suppose that the near point of your eye increases to 46 cm. What is the focal length of your eye's lens when you look at an object at your near point now? f = cm C. With your near point at 46 cm, what is the focal length of the corrective lens (placed directly in front of your eye's lens) which you would need to look at an object that is 25 cm in front of your eye? f = cm D. As you continue to age, the corrective lenses will no longer be sufficient to allow you to see an object that is 25 cm in front of your eye. When you are wearing your corrective lenses, suppose that you can now see objects only if they are no closer than 36 cm in front of your eye. What is the actual near point of your eye now? N = cm What is the focal length of your eye's lens that corresponds to this new near point?

Atension test was conducted on a specimen of aisi 1020 hot-rolled steel having an initialdiameter of 9.11 mm. representative test data are given in table1in the form of force and engineering strain. for strain the extensometer gage length was li= 50.8 mm. in addition, minimumdiameters were measuredmanually with a micrometer in the necked region at several points during the test. after fracture, thebroken halves were reassembled, and the following measurements were made: (1) marks originally 25.4 mm apart and on opposite sides of the necked regionwere 38.6 mm apart due to the lengthwise stretching in the specimen; (2) similar marks originally 50.8 mm apart were 70.9 mmapart; (3) the final minimum diameter in the necked region was 5.28 mma) determine the following material properties: elastic modulus, 0.2% offset yield strength, ultimate tensile strength, percent elongation, and percent reduction in area. b) assume that the test was interrupted upon reaching a strain u = 0.007, and the specimen unloaded to zero force. estimate the elastic strain recovered and the plastic strain remaining. also, what would the new length of the original 50.8 mm gage section. hint: might save time/effort to use excel, mathcad, matlab, etc. to solve part a)table1 data and analysis for a tension test on aisi 1020 hot-rolled steeltest dataforce (p, kn)1. 0.002. 6.673. 13.344. 19.135. 17.796. 17.217. 17.538. 17.449. 17.2110. 20.7711. 24.2512. 25.7113. 25.7514. 25.0415. 23.4916. 21.3517. 18.9018. 17.39engr. strain (ε)1. 02. 0.00053. 0.00104. 0.00155. 0.00236. 0.00317. 0.00508. 0.00709. 0.010010. 0.049011. 0.125012. 0.218013. 0.234014. 0.306015. 0.330016. 0.348017. 0.360018. 03660diameter (d, mm)1. 9.112. 9.113. 9.114. 9.115. 9.116. 9.117. 9.118. 9.119. 9.1110. 8.8911. 8.8912. 8.2613. 8.2614. 7.6215. 6.9916. 6.3517. 5.7218. 5.28