The Scientific Slugger imitates a ball being hit perfectly by a major league player.
In order to see what makes a home run, try adjusting the strength of your swing and the angle at which the ball leaves bat. You can also vary the pitch speed to create more complex combinations. Try changing one variable at a time, and notice what happens.
The distance a baseball travels depends on two primary factors: the angle at which the ball leaves the bat, and how fast the ball is hit. The speed of the ball depends on both the speed of the pitch and the speed of the bat. If the bat is standing still and the ball hits it, the ball will bounce off the bat with most, but not all, of the pitch speed. (Some of the energy is wasted in the friction of deforming the ball, making a sound, etc.) If the ball is standing still and is hit by the bat, it's given a good portion of the bat's speed. Combine the two and you can see that a pitched ball hitting a swinging bat gains a good portion of the sum of both the pitch and the bat speed.
Gravity is always pulling downwards on the ball. If you hit the ball straight up, it spends quite a bit of time in the air, but doesn't travel far from home plate. If you hit the ball horizontally, as in a line drive, the ball moves away from home plate at maximum velocity, but quickly hits the ground because of gravity -- still not very far from home plate. To maximize your hitting distance, you need to have both a high horizontal velocity AND you need to keep the ball in the air for a longer time. You can do this by hitting the ball at an upward angle.
If there were no air resistance (that is, if a ball didn't have to make its way through the air on its way out of the park), the ball would travel nearly twice as far. Air resistance depends on humidity, temperature, and altitude: To make a ball go farther, you want high humidity, high temperature, and high altitude. The Scientific Slugger is set for constant air resistance based on zero humidity, at 56 degrees Fahrenheit, all played at sea level.