(a) Apply Newton's second law: The net force on the car is given by the equation:

\(DF - 650 = 1800 \times 0.5\)

Solving for DF gives:

\(DF = 1800 \times 0.5 + 650 = 1550\)

The power P is given by:

\(\frac{P}{20} - 650 = 1800 \times 0.5\)

Solving for P gives:

\(P = 1550 \times 20 = 31,000 ext{ W or } 31 ext{ kW}\)

(b) To find the steady speed, use the power equation:

\(\frac{31,000}{v} - 650 = 0\)

Solving for v gives:

\(v = \frac{31,000}{650} = 47.7 ext{ m s}^{-1}\)