A tall cylinder is filled with viscous oil. A round pebble is dropped from the top with zero initial velocity. From the plot shown in the figure, indicate the one that represents the velocity (v) of the pebble as a function of time (t).
The answer is the option (c)
When a cylinder is filled with viscous oil and a pebble is dropped from the top, it falls under the effect of gravity and acceleration due to this force. When it enters the oil, a dragging force acts the opposite, and hence, the acceleration of the pebble decreases till it becomes zero,o, and the velocity becomes constant. Hence option c is correct.