Trepidation and a healthy fear are wise when hauling a trailer, especially if it's not something you do often. Still, modern trucks are equipped with a host of safety features to keep you and your load moving safely down the road. That doesn't mean you still can't mess things up, of course.
Here's a very simple tip that can make your towing adventures much safer: Put the weight as close to the front of the trailer as possible.
As you can see in the demonstration video, a trailer with its weight set forward is easier to control. Once the weight moves to the rear, the model car can no longer handle the swinging movement and sideways forces (like wind or the aerodynamic effect of another passing trailer) make it lose control. The simple act of putting the weight at the front of the trailer helps stabilize the load.
U-Haul, the source of this demonstration, recommends this on its trailer usage tips page. By putting 60 percent of the cargo weight on the front half of the trailer, you can help mitigate potential trailer whip scenarios. Additionally, if you do find yourself in such a situation, be sure to ease off the throttle to slow down your vehicle. This should help you reduce the sway. Once you're able to come to a stop, it's time to reposition your cargo to make sure the weight is properly shifted (and held) forward in or on the trailer.
Sometimes all it takes is a model car demonstration to help us better understand physics.