How, in terms of particles, do these 2 types of mixtures differ?

Using the work energy theorem. what is the velocity of a 850kg car after starting at rest when 13,000j of work is done to it.

A2000 kg car is rounding a curve of radius 200 m on a level road. the maximum frictional force the road can exert on the tires of the car is 4000 n. what is the highest speed at which the car can round the curve?

Why is the energy that results from a roller coaster's position at the top of a hill referred to as potential energy?