Solving for Speed, Height of Boy on Water Slide

[Fermat]

vi = 10 m/s is correct.

But this is the vertical velocity (when he hits the water)
You already know the horizontal velocity, vf at the slide.

Use pythagoras to get the speed (do you know what I mean ?)

 

[hannsparks]

a2 + b2 = c2?

 

[Fermat]

I assume you mean,

a² + b² = c²

or,

vf^2 + vi^2 = speed^2

 

[hannsparks]

so it would be 10^2+ 0^2=speed^2

 

[hannsparks]

no that doesn't make any sense because the speed would be the same as the final speed, so we have to calculate the vi some how

 

[hannsparks]

would it make sense to solve for vi using the conservation of energy equation?

 

[Fermat]

Sorry, I've missed out a step.

I thought you had already worked out another velocity.

Ok, forget my earlier post about vi being a vertical velocity - that's wrong.

the 10 m/s, that is the horizontal velocity that the boy has when he leaves the slide. I think you called that Vb.

Ok, now we have to find the vertical velocity that the boy hits the water with.

He falls from a height h = 2.4 m ( the height of the slide above the water). He falls with a acceleration of g = 9.8 m/s². So,

v² - u² = 2as (with u,v,a,s as defined before)

v² - 0 = 2g*2.4
v = 6.858 m/s
===========

Then,
v² + Vb² = speed²

 

[hannsparks]

wow! thanks fermat for all your patience with me I greatly appreciate it! I only discovered this website two days ago and I thank God I did you've been a tremendous help. thanks again

 

[Fermat]

Ciao