Describe a theme park ride that has a constant speed but changing velocity?

Well,

Let's just say that the Jaguar! (a certain ride in Knott's) could instantly go from zero speed to, let's say, 40 mph, and vice versa.  We know (if you have ridden it) that the Jaguar! is not a straight line, as you can't say that it is always traveling at 40 mph due north (otherwise it would never be able to make a loop)!

Remember that, since velocity is a vector quantity, a change in direction will constitute a change in velocity.

The changes to agriculture in the united states since 1900 is that increased mechanization has increased food production, thereby increasing the need for labor. there has been an increased need for higher speeds of food production due the fact that the population in the united states continues to rise.