Question

If a ball is thrown into the air with a velocity of 42 ft/s, its height (in feet) after t seconds is given by y = 42t − 16t2. Find the velocity when t = 1.

Answer 1

$\bf y=42t-16t^2\implies \left. \cfrac{dy}{dt}=42-32t \right|_{t=1}\implies 42-32\implies 10$