Shall we do a simple units analysis?

来源: Bonbon330S 于 2005-12-08 17:46:34 [] [旧帖] [给我悄悄话] 阅读数 : (417 bytes)
回答: No rpm is involved. 由 Bonbon330S 于 2005-12-08 16:49:20

Torque - Newton * meter
Force - Newton
Radius - meter
Gear ratio - unitless
rpm - 1 / second

Now, in my formula,

Force_at_wheels = Torque_at_engine * Gear_ratio / Radius,

both sides have units = Newton.

Now, you multiply rpm to the right-hand side, and its units becomes Newton / seconds. I don't know of any meaningful physics concept that has Newton / seconds as units.

所有跟帖： 

• 你还不明白，能量守恒！ -ifidonlike- ♂ 给 ifidonlike 发送悄悄话 (320 bytes) () 12/08/2005 postreply 18:13:12

• 你那个方程唯一有效的时候是引擎和车轮都是静止的时候才有效 -Bonbon330S- ♂ 给 Bonbon330S 发送悄悄话 (287 bytes) () 12/08/2005 postreply 18:31:19

• 回复：你那个方程唯一有效的时候是引擎和车轮都是静止的时候才有效 -ifidonlike- ♂ 给 ifidonlike 发送悄悄话 (324 bytes) () 12/08/2005 postreply 21:18:51

• 我得承认你的计算方法是对的，但你假设的比例有问题所以导致结论不对 -ifidonlike- ♂ 给 ifidonlike 发送悄悄话 (0 bytes) () 12/08/2005 postreply 21:54:12

• 举例时车轮的rpm（车速）也要考虑 -ifidonlike- ♂ 给 ifidonlike 发送悄悄话 (0 bytes) () 12/08/2005 postreply 22:00:05

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