A car accelerates uniformly from rest to $20.0 \mathrm{m} / \mathrm{s}$ in $5.6 \mathrm{s}$ along a level stretch of road. Ignoring friction, determine the average power required to accelerate the car if (a) the weight of the car is $9.0 \times 10^{3} \mathrm{N}$ and (b) the weight of the car is $1.4 \times 10^{4} \mathrm{N}$.