Downhill Physics 101
Once, while dating my sweetie, I parked my brand new 1974 Nova SS in front of her parent's house. When I came out a few hours later, my car was gone. Poof! It wasn't until I was fully out of the house standing in the middle of the driveway that I realized my car had slid 50-60 feet, just inches away from several giant maple trees, nearly onto the busy 55mph road. What my hormone hopped up brain hadn't counted on was that the icy, gently sloped driveway would begin to melt ever so slightly under the tires. (Psst. Ignoring my poor parking choices, she married me 44 years ago.)
Whenever we park we should always evaluate our landing zone. Slope, for and aft, side to side. Gravel. Ice. Mud. Even parking on wet grass and leaves could turn out to be our hardest physics lesson. Using tire chocks may just be the best decision you ever made.