Respuesta :

pstnonsonjoku

Answer:

8 seconds

Explanation:

From Newton's second law;

Ft = m(v-u)

F = Force applied

t = time taken

v = final velocity

u  = initial velocity

20 * t = 32 (9 - 4)

20t = 32 * 5

t = 32 * 5/ 20

t = 8 seconds