问题
填空题
When an object is dropped, the number of feet N that it falls is given by the formula 
, where t is the time in seconds since it was dropped and g is 32.2, if it takes 5 seconds for the object to reach the ground, how many feet does it fall during the last 2 seconds ？（）
答案
参考答案：257.6
解析：
根据题意可知，前3秒钟该物体下落的距离为：
[*]英尺
同理5秒种该物体下落的距离为：
[*]英尺
最后2秒下落的距离等于5秒钟下落的距离减去前3秒下落的距离：
402.5-144.9=257.6英尺。