4. Give the model (differential equation) that describes a spring mass system serving as a shock absorber under a car's suspension, supports the M = 1000 kg mass of the car. For this shock absorber, k = 3 × 10^3 N/m and c = 2 × 10^3 N s/m. The car hits an unexpected hump in the road and experiences a constant force of F = 10 × 10^3 N from t = 0 till t = 2. (Do not solve the differential equation)