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運動力學 20分 torque and angular

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Question pictureTorquehttp://upload.lsforum.net/users/public/b424061v176.pnghttp://upload.lsforum.net/users/public/h77662n176.pngHow to do?angularhttp://upload.lsforum.net/users/public/j210433v176.pnga.20=0.7x angular velocityangular velocity= 28.6 rad/sb.average angular acceleration=28.6/0.4 average... 顯示更多 Question picture Torque http://upload.lsforum.net/users/public/b424061v176.png http://upload.lsforum.net/users/public/h77662n176.png How to do? angular http://upload.lsforum.net/users/public/j210433v176.png a. 20=0.7x angular velocity angular velocity= 28.6 rad/s b. average angular acceleration=28.6/0.4 average angular acceleration=71.4rad/s/s c. average tangential acceleration=0.7x71.4 average tangential acceleration=50m/s/s d. average radial acceleration= 0.7x28.6^2 average radial acceleration=572.6m/s/s e. how to do? 更新: 1.(a) (ii) Torque = 35 x 0.3sin(45) N.m = 7.425 N.m Sin 45 點來?可唔可以畫幅圖來?

最佳解答:

1.(a)(i) Torque = 35 x 0.3.sin(0) N.m = 0 N.m (ii) Torque = 35 x 0.3sin(45) N.m = 7.425 N.m (iii) Torque = 35 x 0.3sin(90) N.m = 10.5 N.m (b) Let F be the medial deltoid force At position B: [F.sin(15)] x 0.05 = 7.425 i.e. F = 574 N At position C: [F.sin(15)] x 0.05 = 10.5 i.e. F = 811 N (c) The medial deltoid muscle needs to contract in order to give the necessary torque. 2.(e) Assume the pitch is completed in 0.4 s as before, the angular velocity will remains the same. Shortening the pitching arm will give a lower tangential speed of the ball at release. 2015-05-04 16:13:45 補充: Q:Sin 45 點來? A: The arm is lifted at 45 degress with the vertical. 0.3sin(45) is the perpendicular distance between the arm's weight and the shoulder joint.

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