In order to dunk a basketball, Jim must jump to a height of 1.2 meters. He can jump with an initial velocity of 5.1m/sec. Can he dunk? (quadratic solution?)

Question

In order to dunk a basketball, Jim must jump to a height of 1.2 meters.  He can jump with an initial velocity of 5.1m/sec.  Can he dunk? (quadratic solution?)

anonymous · Answer

We know u=5.1, s=? a=9.8 and final velocity = 0
Using $$v^2=u^2+2as$$

anonymous · Answer

$$0=5.1^2 + 2 (-9.8)s$$

anonymous · Answer

So a = -9.8 sorry

anonymous · Answer

Solve for s (displacement) if >1.2 he can dunk :) that ok?

anonymous · Answer

I'm supposed to use the quadratic formula to solve this one, specifically the discriminant.

anonymous · Answer

Um

anonymous · Answer

Yeah, that's what I said!

amistre64 · Answer

the physics quadratic for this is:$$h=-\frac12gt^2+v_ot+h_o$$

amistre64 · Answer

the quadratic formula can tell us when he jumps, and when he lands,  the determinant really isnt all the useful to us in determining the vertex of the parabola tho

amistre64 · Answer

i spose when h=1.2 ... that will zero things out in the end

amistre64 · Answer

$$1.2=-4.9t^2+5.1t$$
$$4.9t^2-5.1t+1.2=0$$
and i see i confused all the d terms,  discriminant is the axis of symmetry value

anonymous · Answer

This question was part of an assignment that started with the outcomes wen the "discriminant" was positive vs. negative in an algebra quadratic formula, so I'm guessing he's driving at my being able to put the information given into that formula.  So much for explicit teaching!!

amistre64 · Answer

discriminant is defined as:  -b/2a

5.1/2(4.8) = t

amistre64 · Answer

.... my fingers hate me today :)

anonymous · Answer

Not sure where the 4.8 and 4.9 came from.