Force = mA

edit1: corrected by ST
edit2: added new comparisons


[units needed]
mass --> kg
acceleration --> m/(s^2) http://en.wikipedia.org/wiki/Acceleration

1. Being hit by Superman at escape velocity
m = 120 kg
Velocity = Mach 9
A = 2970 m/(s^2))
F = 1,058,508,000 N

2. Force of a passenger hitting windscreen/seat in a car accident
m = 60 kg
Velocity = 80 kph
A = 22.22 m/(s^2))
F = 29,624 N

3. Force of a assault rifle round
m = 3.95-5.18 g (0.00395-0.00518 kg)
Muzzle Velocity = 990 m/s
A = 772–930 m/(s^2) -- apparently, energy is lost. so the Force for the paintball pellet should be lower
F = 2,354 - 4,480 N

4. Force of a 9mm handgun round
m = 7.5-9.5 g (0.0075-0.0095 kg)
Muzzle Velocity = 300-360 m/s
A = 300-360 m/(s^2) -- assuming no energy loss for simple calculation
F = 675 - 1,231 N

5. Force of a paintball pellet
m = 3 g? (0.003 kg)
Muzzle Velocity = 90 m/s
A = 90 m/(s^2) -- assuming no energy loss for simple calculation
F = 24.3 N



Conclusion:
a. It's easier to dodge a speeding car
b. Belt up!

edit: [courtesy of ST]
force needed to propel a paintball pellet
http://answers.yahoo.com/question/index?qid=20080307185202AAyfPfU