What is the most important reason to control the conditions of an experiment?

Imagine that someone pushes one marble toward a motionless marble. would there still be action-reaction forces involved in the collision? how might the marbles’ motions be changed? ?

Assume this car is driven off a cliff . how many arrows of force need to be drawn in the free body diagram? assume no air resistance -five -one -three -four

Which is not true of the intertropical convergence zone? a) it features heavy precipitation b) it's where the trade winds collidec) it's a high-pressure zone with sinking air d) it is also known as the doldrums