Answer:
a = 40.937 m / s²
Explanation:
For this exercise let's use the relationship between momentum and momentum variation
I = Δp
F t = m v_f - mv₀
F = m (v_f -v₀) / t
let's reduce the magnitudes to the SI system
v_f = 47 km / h (1000m / 1 km) (1h / 3600 s) = 13.056 m / s
v₀ = - 65 km / h = -18.056 m / s
the negative sign is bearing the speed is west
let's calculate
F = m (13.056 + 18.056) / 0.76
F = m 40.937
now we can use Newton's second law
F = m a
m 40.937 = m a
a = 40.937 m / s²