If a stone is dropped from a height of 400 feet, its height after t seconds is given by s = 400 − 16t2. Find its instantaneous velocity function.

Explanation:

given,

s = 400- 16 t²

we know,

Velocity of an object is defined as the change in displacement per unit change in time.

velocity an also be return as

Hence, instantaneous velocity function given by

To calculate instantaneous velocity, you need to insert value of time.

ex, instantaneous velocity at t = 4 s

       v = -32 x 4 = -128 m/s.

i believe the answer is a