Question

From what height must a water balloon be dropped in order to have a velocityof 12 m/s when it reaches the ground? (Hint: KEinitial = 0, PEfinal = 0.)A. 15 mB. 0.61 mC. 72 mO D. 7.3 mSUBMIT

Answer 1

D. 7.3 m

Explanation:

We can calculate the value of the height, from the following formula:

`\begin{gathered} v^2-u^2=2ah \\ \text{ in this case} \\ v=0 \\ a=-g=-9.8(m)/(s^2) \\ u=12\text{ m/s} \end{gathered}`

We replace and solve for h what would be the height, like this:

`\begin{gathered} 0^2-12^2=2\cdot-9.8\cdot h \\ h=(144)/(19.6) \\ h=7.3\text{ m} \end{gathered}`