Prove algebraically that a ball thrown vertically upward with a certain speed, will have the same velocity when it comes back to its starting position

Question

Need help for a physics assignment due in a couple hours HELP!

Answer 1

Hi everyone--first, I should admit that the math and physics here are beyond me, but I think what Surendra is saying is that when the ball reaches its maximum height, it has come to a stop, and so at that instant, as there is no speed or direction, it is at a velocity of 0, which will be the same as when it lands and stops moving again.

 

That said, I think the wording of the question is not great--it should be more specific than "a ball thrown vertically..."

 

Hope I didn't just confuse Egemen more. :-)  And yeah, Egemen, tell those teachers at Au Sable Valley to ease off the late-nite math!

 

(I work at a camp in Keeseville during the summers!)

 

Best to all,

 

Matt

Answer 2

Equation of motion vertically up----

 

v^2=u^2-2gh

 

Final velocity is zero, when reaches maximum height.

 

h=(u^2)/(2g)

 

Equation of motion vertically down------

 

Initial velocity =0

 

v^2=u^2+2gh

 

v^2=2g*h

 

      =2g*(u^2)/2g

 

      =u^2

 

That means---

 

v = u

 

final velocity at reaching ground =  initial velocity of throw from ground.