"iPhone 5c is beautifully, unapologetically plastic, the better to bring its five decidedly uncommon colors to life. Beneath the smooth surface of the seamless outer shell, a steel-reinforced frame provides structural integrity. So iPhone 5c feels reassuringly solid in your hand." - Bro! Did you listen to that stumpypants speak!? He had a powergraph!
When you hit one of your hands with the other at just the perfect speed and velocity to get that distinguished, full, and powerful clapping noise.
The way (or angle) in which the hands connect is often much more important to the successful execution of the powerclap than the speed at which you clap them.