Question

Note: the 2 in the answers are exponents

Answer 1

Final speed after collision with the wall

$v_f = -0.4 m/s$

before collision the speed of ball initially

$v_i = 0.6 m/s$

time taken for the collision

$\Delta t = 0.2 s$

now as per the formula of acceleration we know that

$a = \frac{v_f - v_i}{\Delta t}$

now plug in all values in it

$a = \frac{-0.4 - 0.6}{0.2}$

$a = -5.0 m/s^2$

so acceleration is - 5 m/s/s for above situation