**QUESTION**

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1. Young's modulus is a physical quantity to describe the rigidity of a material. Which factor of the material is related to Young's modulus? Multiple-Choice (2 Points) A. Size and shape B. Processing and manufacturing methods C. External force D. Structure and chemical composition 2. When measuring the the length of metal wire, the length of optical lever arm, the distance between scale and flat mirror and the diameter of wire, the uncertainty of $0.5 \mathrm{~mm}$ is also produced. Which one has the greatest influence on the measurement result of Young's modulus? Multiple-Choice (3 Points) A. The diameter of metal wire B. The distance between ruler and flat mirror C. The length of optical lever arm D. The length of metal wire

3. Young's modulus is larger, which indicates that under the same force, the shape change of material is larger when the material is compressed or stretched. True/False (2 Points) A. False B. True 4. In the young's modulus experiment, because it can't guarantee that the tested material is perfectly elastic and has certain plasticity, the material will not recover completely in the process of loading and unloading, and the reading will be slightly different. Therefore, it is necessary to make the weight reduction measurement after the woight addition measurement. Truo/False (2 Points) A. False B. True

5. The magnification of optical lever is $2 \mathrm{D} / \mathrm{b}$. In the experiment, we can try to 0 to make $2 \mathrm{D} / \mathrm{b}$ larger. $D$ is the distance of the scale to the flat mirror. $b$ is the length of optical lever arm. Mulliple-Choice (3 Points) A. Increas ob appropriately B. Reduce $b$ at will C. Reduce b appropriately D. Increase D at will 6. If the diameter of the metal wire is doubled and the others remain unchanged, the elongation per $1 \mathrm{~kg}$ weight will be $1 / 4$ of the original. TruerFalse (2 Points) A. True B. False

7. In the experiment of measuring Young's modulus of metal wire, it is often necessary to preload $1 \mathrm{~kg}$ weight. What is its function? Multiple-Choice (2 Points) A. Eliminate friction B. Eliminate zero position error C. Straighten the matal wire D. No effect 8. Is the young's modulus of two steel wires with the same material and different diameter the same? Multiple-Choice (2 Points) A. The young's modulus of the motal wire with smaller diameter is larger. B. Uncertain C. Same D. The young's modulus of the motal wire with larger diameter is largec,

9. Is the following statement true or false? Measurement of length and diameter of the metal wire: we use the meter to measure the length and the spiral micrometer to measure the diamieter. The measurement results are written to $0.1 \mathrm{~mm}$ and $0.001 \mathrm{~mm}$. True/False (2 Points) A. True B. False