physics about mechanics

2008-09-20 9:32 pm

A vehicle moves up a road inclined at an angle θ to the horizontal with a
constant velocity of 10m/s, if the forces resisting the movement of the
vehicle are uniform, the power developed by the vehicles engine is ?

A. constant
B. increasing uniformly
C. decreasing uniformly
D. increasing,but not uniformly

請教2條問題!

第一，用中文解釋一次條問題
第二，解答此問題，並加解釋
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回答 (1)

用戶35015

2008-09-20 9:55 pm

✔ 最佳答案

答案是A

這條問題是：一輛汽車在與地平面(水平)成角θ 的路上行駛(A vehicle moves up a road inclined at an angle θ )，它的速度是10 m/s ，保持不變(constant)。如果作用於汽車上，阻礙汽車運動的力是均等(uniform)的。那汽車的功率(power)是？

A. constant
B. increasing uniformly
C. decreasing uniformly
D. increasing,but not uniformly

由於作用於汽車的阻礙力和速度都是不變(i.e. resisting force and velocity are constants)，而Power 是 Fv ( Force x velocity ) 。如果Force 和 Velocity 是constant ，Power 也是constant

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