If you need to cut through some wood in a hurry, the rip saw is most likely the right choice for you. The rip saw is used specifically for cutting through wood, and will cut with the grain of the wood. A rip saw is usually going to be anywhere from 24″ to 26″ long, and will have around seven teeth per inch on the blade.
Use a rip saw when you need a powerful, quick blade to cut through some wood. If you are not worried about the smoothness of the cut, the rip saw will do just fine for you. As the rip saw has fewer teeth and cuts with the grain, however, you are not going to get the smoothest edge possible. For a smoother edge, you may want to go with something like a cross cut saw. The rip saw, however, will cut through wood faster than the cross cut. If the speed of the job is a higher priority, then the rip saw is going to be your best bet.
A ripsaw blade acts as a chisel that cuts in parallel with the grain of the wood. Rip saw teeth are not angled forward or back like other saw types, but are flat, so as to push through the grain of the wood. This produces a very straight cut with the wood, if not the smoothest edges possible. Most rip saws are designed to do their cutting action on the push stroke of the blade. Some rip saw blades, such as many made in Japan, may actually do their cutting action on the pull stroke of the blade.
If the speed, straightness, and power of the cutting action is all you are focused on, then a rip saw type blade should accomplish everything that you need. For smoother cuts, you may want to look into something like the cross cut saw. A plytooth blade may also work if you are looking for that finely cut smooth edge.