Passage VI
An object falling through a liquid has 3 forces acting on it: gravity, a buoyant force, and drag (a force that opposes motion). If the net upward force on the object is equal in magnitude to the net downward force on the object, then the object will fall at terminal speed.
A steel ball was dropped from rest into a column of motor oil and into a column of glycerin. Figures 1 and 2 show how the speed of the ball and the drag on the ball varied with time as the ball fell through the oil and through the glycerin, respectively. Figure 3 shows how the depth of the ball varied with time for each case.
35. Based on Figure 3, the depth of the steel ball in the motor oil at time = 50 msec would most likely have been closest to which of the following?
Your Answer is
Correct Answer is D
Explanation
See figure 3, according to the slope of the motor oil curve, when the abscissa time=50mesc, the ordinate depth should be greater than 1.9mm, so 2.10mm is reasonable