Reaction force in bouncing balls

[taqi]

Ive seen in my book, that when a ball is bouncing, and is at rest (at max compression hitting the floor, just before it starts going up again), Fn >> Fg, so the normal force is much greater than the weight force. But how can this be? if the ball is at rest, then aren't all the forces equal, so no movement?

[moekamo]

it can be at rest, but there is still an acceleration, think of throwing a ball in the air, when it is at the top of its flight it is stationary, but gravity is still acting on the ball, so there is still a force and an acceleration.

[xZero]

The velocity is 0 but there can still be acceleration.( the gradient of the velocity graph at 0 can be anything) hence net force doesn't have to be 0

[kushwoho44]

The velocity is 0 but the can still be acceleration.( the gradient of the velocity graph at 0 can be anything) hence net force doesn't have to be 0

Yeh, same as when you're throwing a ball in the air. It's acceleration is a constant 10 metres per second per second towards the earth yet at the top of it's flight it's velocity is zero.

[taqi]

ah yes, that makes sense. thanks

[VivaTequila]

this is something i've always struggled to understand conceptually, but meh. just come to accept it.

i just think of it using methods, if you have a quadratic, at it's turning point the gradient equals zero, but if you sketch the derivative of the quadratic you'll find that the gradient function is on a slope.

i find imagining the slope of the derivative helps, but that's just me, don't know if it has any relevance but it's a helpful analogy