A 2.7 kg cart is rolling across a frictionless, horizontal track toward a 6.4 kg cart that is held initially at rest. The carts are loaded with strong magnets that cause them to attract one another. Thus, the speed of each cart increases. At a certain instant before the carts collide, the first cart's velocity is 4.1 m/s, and the second cart's velocity is -1.9 m/s. What was the velocity of the first cart when the second cart was still at rest

the independent variable, or the one that is intentionally manipulated is the speed.

first thing first of the answer is with technology. second thing second thing is that the big bang theory did not happened u see they say it did but what they dont realize is that like dinasures are still a round they might deny it but they and look at these 12 foot human skelteons they find lets see didnt the bible say something about giants. hope this peace.