# who enters the water first? by how much? In a diving siblings showcase, 11 year old Hannah takes off from a 24.61 foot platform with an initial velocity of 9.7 ft/sec at the same time that her...

who enters the water first? by how much?

In a diving siblings showcase, 11 year old Hannah takes off from a 24.61 foot platform with an initial velocity of 9.7 ft/sec at the same time that her brother Tyler, who is 3.5 years older, takes off from a 32.81 foot platform with an initial velocity of 4.51 ft/sec. round to the nearest hundredth.

lfryerda | High School Teacher | (Level 2) Educator

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The height function for constant acceleration is `h=-1/2 g t^2+v_0t+h_0` where `v_0` is the initial velocity and `h_0` is the initial height.

For both children, the time to enter the water is found by setting the height to zero and solving for t.

For Hannah, we need to find the time by solving:

`-1/2(32)t^2+9.7t+24.61=0`

`t={-9.7-sqrt{9.7^2+4(24.61)(16)}}/{2(-16)}`   using negative root to keep time positive

`=1.58`

For Tyler, solve the equation:

`-1/2(32) t^2+4.51t+32.81=0`