In the famous Road Runner cartoon, Wile Coyote often runs off a cliff, slows down, and then falls once he realizes that he is no longer standing on solid ground. And while this may be humorous, it makes no sense scientifically. As a matter of fact, this cartoon violates two principles: horizontal acceleration and gravity.
First, horizontal acceleration. In the cartoon, once Wile E Coyote runs off the cliff, he begins to slow down and eventually comes to a stop. That, however, is impossible. According to Newton’s first law of motion, objects moving at a uniform speed will remain in that state unless acted upon by an external force. This means that there would have to be some sort of outside force at work to make the coyote stop completely. Looking at the cartoon, the only external force acting on the character is air resistance, meaning it could be the only thing that stops the horizontal motion. However, since the coyote was already able to accelerate and achieve uniform motion, the only way for the air resistance to possibly achieve the desired effect would be for Wile E Coyote to have a different mass before and after running off the cliff. And since the law of conservation of mass says that such is not possible, there is no way that the coyote could have run off the cliff without maintaining a near uniform velocity.
Second, gravity. According to Newton’s universal law of gravitation, gravity is a constant force. However, in the cartoon, it takes several seconds in order for the force to take effect on the character. In reality, the Coyote should have begun falling the second he stepped of the cliff. Additionally, in the cartoon the Coyote often continues running on the air. But since there is no ground to exert a normal force on his feet while he is running, it is impossible for his legs to continue to propel him forward. As a result, there are no conceivable explanations for the antics of Wile E Coyote.