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.
40. Based on Figures 1 and 3, at a depth of 0.50 mm in the motor oil, what was the approximate drag exerted on the steel ball?
Your Answer is
Correct Answer is H
Explanation
Look at the motor oil curve in figure 3 first, when the depth of the ordinate is 0.5mm, the time of the abscissa is about 15msec;
Then correspond to the drag curve (dashed line) in figure 1, when the horizontal When the coordinate time is 15msec, the ordinate drag is about 270 μN