Physics of balls

Adam Szalai

Jurisich Miklós High School

KŐSZEG

I love sport,

I like to play football,

And I also love sciences…

I love basketball,

The ball•Size, shape, mass, material, elasticity – all depending on the sport

•Soccer, basketball, volleyball, handball, football, baseball, la-cross, golf, table tennis, tennis, bowling, snooker etc.

What happens to the ball?

•Collision–Starting: energy is given to the ball

• With rackets, hands, foot, stick, cue …

–Collision is more or less elastic

–Conservation of momentum can be used during the collision (angles!)

Deformation• Can be observed in low-speed movies

• Can be observed in case of slow motion (bubbles)

• Volume is approximartely the same

• Smaller surface bigger surface

Motion of the ball

• Rolling on the surface–Slows down and stops b/c of friction

–(E.g. golf; bowling etc.)

–Depends on the friction

Motion in the air

•Theoretically: projectile. The path is parabola– Vertically: uniformly accelerates (g)– Horizontally: Uniform motion

•In practice: air resistance affects the path

Why does the path bend?

• Air „sticks” to the spinning objects

• As spinning body moves, the relative speed is different, pressure is different (Bernoulli law)

Speed – pressure2

2

1vpp o

p

Vrelp

Vrel

Magnus effect

• In sport - bent path of the balls

• In traffic - on a two-lane road two oppositely moving cars

• Helicopters

• Etc.

Be careful with it; take advantage of it, you might become

famous…