Learning Impulse and Momentum Is A Piece of Cake

Impulse can be defined as the 'change in momentum', or the average force multiplied by change in time. Impulse is a vector, just like momentum, and uses the same units (kg m/s). Let's work on finding the impulse in this problem. A 0.015 kg cake (like the one I have shown above) is thrown into the wall with a speed of 100 m/s. If the cake miraculously doesn't crumble and instead bounces back with a speed of 80 m/s, what is the impulse?

Well, first, we'd find the momentum. P=mv is P=.015 kg *100 m/s = 1.5 kg m/s. Then, P= .015 kg * 80 m/s = 1.2 kg m/s. When those two momenta are added together, you get 2.7 kg m/s, which is the change in momentum, or IMPULSE. And that, my friend, is the easiest way to have your cake and eat it, too. Although I'm not too sure why you'd throw that cake to begin with...