It,too,is hungry. Traveling across the ground at great speed, the cat nears the area where the pig is fighting for its life.

VOA: special.2010.04.07

When does it hit the ground and at what speed?"

该物体何时落地,落地速度是多少

耶鲁公开课 - 基础物理课程节选

Remember, you've got to keep track of the sign of acceleration, so if you're picking up speed towards the ground, a is negative, so it will be g plus a, but a is a negative number.

记住,一定要注意加速度的符号,所以当你加速下降的时候,a 是负的,还是 g 加上 a,但是 a 是负数

耶鲁公开课 - 基础物理课程节选