關於物理的簡單問題

1. As shown in the figure, a 3-kg mass is being pulled by a string such that the mass is accelerating uniformly to the right. Suddenly, the string breaks. Estimate the acceleration of the mass just before the string breaks, given that the maximum tension in the string is 200 N.

http://i617.photobucket.com/albums/tt257/michaelcoco_/4.jpg


The answer is 65.9 ms^-2.

2. 2. In the figure, a ball of mass m falls vertically down on a weighing scale with speed v just before impact. The ball rebounds with the same speed after the impact as shown. If the impact time is t, what will be the average reading of the weighing scale during the impact?

http://i617.photobucket.com/albums/tt257/michaelcoco_/6.jpg


The answer is mg + (2mv) / t.


※試列明計算步驟※