Your brother goes down the (smooth) slide first without any difficulty and makes it to the end, but then as a prank he takes a handful of sand and throws it onto the slide. When you go down the slide next, you start to slow down when you run into the sand, so that you come to a stop in the middle of the slide.

explain the physics of what happened and why the two situations differed. Address the physics using ideas from both the Forces unit of our class, as well as the Energy unit of our class. Be thorough and demonstrate your understanding.