The screenshot was taken after I threw a crate with more mass against another crate with less mass, launching it a good distance over the other crates. It's not realistic, to say the least, but it actually turned out how I wanted. The physics are more like what you might see in Smash Bros rather than real life. When the main character is throwing cars at that bad guys, I think it will pay off (and yes, I do plan on having that in the game).
Up next, I think I need to get the rest of the main character's moves programmed in. Then I'll probably create some sort of bot enemy to fight against.