Question

An object is thrown downward with an initial velocity of 3 feet per second. The relationship between the distance s it travels and time t is given by s = 3t + 16t2. How long does it take the object to fall 70 feet?

Answer 1

Answer:2 s

Step-by-step explanation:

Given

initial velocity
`u=3 ft/s`

distance travel
`s=3t+16t^2`

time taken to travel 70 feet

`70=3t+16t^2`

`16t^2+3t-70=0`

using
`x=(-b\pm √(b^2-4ac))/(2a)` to get roots

`t=(-3\pm √(3^2-4(16)(-70)))/(2\cdot 2)`

t=2 and -2.19

only feasible time is 2 s

thus it requires 2 s to cover 70 feet