PLEASE HELP An object is thrown upward with an initial velocity of 32.1 m/s. What is its velocity in 4.0 s? (use g = 9.81 m/s2). Please include step by step process. -7.14 11.2 7.14 -4.6

-7.14

Explanation:

According to equation of motion

v = u + at

where

v is the final velocity at any time t

u is the initial velocity

a is the acceleration

and t is the time

Given

An object is thrown upward it means

its initial velocity is in upward direction

but acceleration due to gravity is in downward direction which will cause to decrease the velocity of object.

Intial velocity u = 31.1 m/s

final velocity v at 4 second we have to find.

t = 4 second

a = g = 9.81 m/s2 (it is acting in opposite direction of motion hence its sign will be negative ).

Thus

a = -  9.81 m/s2

using the above values in v = u + at

v = 32.1 - 9.81*4

v = 32.1 - 39.24

v = -7.14

Thus, correct option is -7.14.