Physics education often relies on visualization of theoretical laws. While Java animations are widespread, they mostly lack user interaction. We propose a haptic device inviting users to interact with the law of physics. Based on an in-house design — a generic force feedback slider (FFS) — we have realized a software application simulating a catapult. As users interact, they receive both tactile and visual feedback. By calling upon two perceptual channels at a time, here tactile and visual, we assume users may construct their mental model more easily. This paper presents our application, the underlying FFS technology, a user study, future uses, and a discussion.