REALLY Need help on Projectile motion problem (algebra)?

Question

Problem- Suzie jumps from a 1 meter springboard with an initial upward velocity of 4.9 meters per second.
Questions i answered-
a- write an equation= -4.9t^2+4.9t
b. When will Suzie return to her initial height- 1 second
Questions I need help on-
c. When will she hit the water (water = 0 meters) assuming that you start from the 1 meter springboard.
d.How high above the water does she get?

Thank you.

Answer 1

For c, you need to set the formula equal to -1 and solve for t, since the water is at -1 meter height in the coordinate system you're using (i.e., in the one where the original formula/equation is correct, which is to say the one where the springboard is at 0 height).

The quadratic formula is your friend on that one.

For d I don't know what facts you have and haven't been taught about parabolas and so on, so I don't know what kind of explantion would be legit -- but in fact she reaches the max height at t = 1/2. So plug that into your formula to get her max height ABOVE THE SPRINGBOARD.

Add 1 to get her height above the water.