Question about solving the air resistance force on a table tennis ball?
Written by admin on February 17th, 2009
mysterious_purple_haze asked:
Hi there,
Hi there,
Please can you give me some hints on how to solve this question:
“A table-tennis ball of mass 10g is falling towards the ground with a constant speed of 8.2 ms. Calculate the magnitude and direction of the air resistance force acting on the ball.”
I know obviously the air resistance force is going to act upwards.
How do I solve the actual numerical value of air resistance?
Thanks!
Ok, dont worry… got the answer.
Tags: Air Resistance, Direction, Magnitude
2 Comments at "Question about solving the air resistance force on a table tennis ball?"
On a perfectly windless day, drop it from a high cliff and time its fall.
It will soon reach terminal velocity.
Calculate air resistance from that.
If the ball is falling with a constant velocity, then it is not accelerating.
Because the ball is not accelerating, all the forces acting on it must equal zero.
In this case, there are only two forces (1) the gravitational force pulling downward, and (2) the air resistance force acting upwards.
Thus, the magnitude of the air resistance force must equal the magnitude of the gravitational force. So:
Fair = Fgrav = ball mass * gravitational acceleration
.01 kg *9.8 m/s^2 = 0.098 N
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