1. A meter and 2-meters length wire are pulled with the same force, then the length increase 0.5 mm and 1.0 mm, respectively. If the diameter of the 2-meters wire is twice as long as 1-meter wire, Find the ratio of Young's modulus of 1-meter and 2 meters wire. 2. Three springs have the same constants arranged in series. If at the bottom of spring is hung with a 6 kg weight, the spring extends 5 cm. Find the extension of the spring arrangement if given a load of 8 kg. 3. A 50 cm spring with a spring constant of 200N/m, cut into two equal parts. A spring part is pulled by 40 N force, Find the extension of the spring part. 4. Some pencils each have a cross-sectional area of 0.002 m² are tied together. The maximum stress for each pencil is 22,500 Pa. How many pencils that can be broken at once with 135 Newton force? 5. An elevator using steel wire with a cross-sectional area of 5 cm², that can hold loads up to 25,000 N. for safety reason, the tension of the steel wire must not exceed 25% of its elasticity limit which is 5 x 10⁸ Pa. Determine the maximum lift acceleration that is still allowed (upwards).
1. 1. A meter and 2-meters length wire are pulled with the same force, then the length increase 0.5 mm and 1.0 mm, respectively. If the diameter of the 2-meters wire is twice as long as 1-meter wire, Find the ratio of Young's modulus of 1-meter and 2 meters wire. 2. Three springs have the same constants arranged in series. If at the bottom of spring is hung with a 6 kg weight, the spring extends 5 cm. Find the extension of the spring arrangement if given a load of 8 kg. 3. A 50 cm spring with a spring constant of 200N/m, cut into two equal parts. A spring part is pulled by 40 N force, Find the extension of the spring part. 4. Some pencils each have a cross-sectional area of 0.002 m² are tied together. The maximum stress for each pencil is 22,500 Pa. How many pencils that can be broken at once with 135 Newton force? 5. An elevator using steel wire with a cross-sectional area of 5 cm², that can hold loads up to 25,000 N. for safety reason, the tension of the steel wire must not exceed 25% of its elasticity limit which is 5 x 10⁸ Pa. Determine the maximum lift acceleration that is still allowed (upwards).
1. Y1/Y2 = (d2/d1)^2. (ΔL2/ΔL1)
2^2. (1/0.5) = 8
2. mg = k Δx ==> Δx = (8/6).5 =6.67 cm
3. Δx = (40/200).50= 10 cm
4. (135/0.002)/22,500 = 3
5. a = (T - mg)/m
= (1.25. 5. 10^8. 5. 10^(-4) - 25,000)/2500 = 125 m/(s^2)
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