In: Physics
On the way up, the magnitude of the ball's acceleration is _____.
A ball is tossed straight up. Air resistance is not negligible; the force of air resistance is opposite in direction to the ball's velocity. Assume its magnitude is less than the ball's weight. Answer choices:
(a) Less than g
(b) Equal to g
(c) Greater than g
Let the mass of the ball be m and the force of air resistance be F. The FBD of the ball when it moves down with acceleration ay is shown below:
From the above free body diagram, the weight of the ball (mg) acts in down ward direction. Using the ’s second law of motion, the net force acting on the ball is
Fnet = m(-ay)
= may
When the ball is move down with acceleration, the resultant force acting on the ball is
Fnet + mg = F
-may + mg = F
ay = g – F/m
This shows that the magnitude of the acceleration of the ball is lesser than g. Therefore, the correct choice is (a).
This shows that the magnitude of the acceleration of the ball is lesser than g. Therefore, the correct choice is (a).