Question

$h=-16t^2+vt+k$
The equation above gives the height $h$, in feet, of a ball $t$ seconds after it is thrown straight up with an initial speed of $v$ feet per second from a height of $k$ feet. Which of the following gives $v$ in terms of $h,t$ and $k$?

• A. $v=h+k-16t$
• B. $v=\frac{h-k+16}{t}$
• C. $v=\frac{h+k}{t}-16t$
• D. $v=\frac{h-k}{t}+16t$

Answer 1

Answer: (D)

$v=\frac{h-k}{t}+16t$

Given, $h=-16t^2+vt+k$
$\Rightarrow h+16t^2-k=vt$
$\Rightarrow v=\frac{h+16t^2-k}{t}$
$\Rightarrow v=\frac{h-k}{t}+16t$