This is a demonstration going back to Ch. 5 in Newton's laws. We have a cork attached to a string on a beaker. Once I accelerate this beaker to your right, The cork will tend to stay where it is from an inertial reference frame, which
is you. I will place my hands behind the cork to help you see better. The cork tended to stay where it was until the beaker hit it and was accelerated to your right. We will now add a twist to this demonstration by bringing in fluids. I'm going to fill this
beaker with water. The cork is now afloat in the beaker. Your job is to predict and explain what will happen once I accelerate this beaker to your right. We will show you the answer in another demonstration.