Mr. h ignites the enthusiasm of the class with a home-made cannon demonstration. the 1.27-kg cannon is loaded with a 54-gram tennis ball and placed on the floor. mr. h adds the fuel, waits for its vapors to fill the reaction chamber and then brings a match nearby. the explosion stuns the crowd and propels the ball forward. a photogate measurement determines that the cannon recoiled backwards with a speed of 7.8 m/s. determine the speed of the ball.