Why Can't You Escape from a Black Hole?

How can your students use a water fountain to understanding black holes? One of the most frequently made statements about black holes is that ‰ÛÏnothing can escape from a black hole." But what does this exactly mean? And why can't anything escape?

In this activity, students explore this statement, first, from the perspective of Newton's theory of universal gravitation using the concept of escape velocity. Next, they consider it from the perspective of Einstein's model of gravity (general relativity) using a simple hands-on water-based model of a black hole. They realize for themselves a limitation of Newton's model and how Einstein's model more accurately describes the properties of black holes.