Basketball “Hang Time” Physics

Michael Jordan Flies Through the Air (statue) from Esparta on Flickr

Michael Jordan Flies Through the Air (statue) from Esparta on Flickr

The stadium is packed with fans as Michael Jordan flies through the air on his way to the rim. Gravity seems suspended in this “hang time” phenomenon.

The hot dog dealer casually explains that by using THE TRUTH, and possibly a know/don’t know table, it can easily be calculated that it is true that Jordan spends 2/3 of the time actually in the air and with a vertical leap of over forty inches this can be a long time.

The hot dog dealer continues to explain the physics of the game by showing how vector analysis can track the motion of basketball stars.

A vector has direction and magnitude and can be added or subtracted using normal additive rules.

Thus he explains that the offense can jump both forward and up, but if the defense has the same vertical component they will both land at the same time since horizontal and vertical motion components are independent.

The dealer then continues on his way and warns not to use tangent for the x or y components

Instead, multiply the vector by sin(θ) to find the y component (magnitude in the y direction) and multiply the vector by cos(θ) for the  x component (magnitude in the x direction.

Also, by convention you should measure θ from the positive x-axis (this is physics convention anyway).

Michael Jordan top 40 moments

Golf Ball Physics

Golf Balls Have dimples on their surfaces to minimize drag (a force that dissipates when an object moves through a fluid).

A smooth ball causes the air to flow in such a way that the air “sticks” to the ball longer. The dimples also act to create backspin- which makes the air pressure on the top of the ball decrease- giving it lift (somewhat like the situation with an airplane’s wings).

A smooth ball that ravels 65 meters would travel something like 275 meters with dimples when hit with the same force.

Golf balls have 300-500 dimples that can be 0.25 mm deep.