By applying a force of 6.59-N to a 39.8-kg shopping cart, Carrie accelerates the cart with magnitude a such that
6.59 N = (39.8 kg) a
⇒ a ≈ 0.166 m/s²
so that over a period of 2.05 seconds, the cart's speed increases to
0.744 m/s + a (2.05 s) ≈ 1.08 m/s
Or, if you've been introduced to the concept of momentum and impulse, we get the shopping cart's initial momentum,
p₁ = (39.8 kg) (0.744 m/s) ≈ 29.6 kg•m/s
and its final momentum when it attains speed v,
p₂ = (39.8 kg) v
Then the change in momentum of the cart is
∆p = p₂ - p₁ = (39.8 kg) (v - 0.744 m/s)
and this is equal to the impulse J due to the force Carrie applies,
J = F ∆t = (6.59 N) (2.05 s) ≈ 13.5 kg•m/s
Solve for v :
J = ∆p
⇒ 13.5 kg•m/s ≈ (39.8 kg) (v - 0.744 m/s)
⇒ v ≈ 1.08 m/s