一題 Form 4 Physics - Mechanics 問題

anthony

Santa Claus is riding on a sledge to distribute Christmas presents. The deers apply a force of 5000N to pull a sledge up a slope at a constant speed. The slope is at an angle of 10° to the horizontal. Suppose the friction acting on the sledge is 4250N and the total weight of Santa Claus and the sledge is 3000N. Find the weight of the presents.

答案是 1320N，但是我不懂如何做，希望大家指點。

anthony

原帖由 sapphire 於 28/10/2006 13:55 發表
Let the weight of the presents be x N.

Since the sledge is moving at cont. speed, the net force acting on the sledge along the plane is zero.

5000 = 4250 + ( 3000 + x ) sin10∘
       ...

thank you very much

sapphire

Let the weight of the presents be x N.

Since the sledge is moving at cont. speed, the net force acting on the sledge along the plane is zero.

5000 = 4250 + ( 3000 + x ) sin10∘
       x = 1319.08 = 1320 (corr. to 3 sig. fig.)