Without a net centripetal force, an object cannot travel in circular motion. In fact, if the forces are balanced, then an object in motion continues in motion in a straight line at constant speed. This can be demonstrated by carrying a tennis ball upon a flat, level board. Once the tennis ball and the board are in motion, they will continue in motion in the same direction at the same speed unless acted upon by an unbalanced force. This demonstrates Newton's first law of motion. But if an unbalanced force is applied to the flat board, then the flat board will accelerate. If the force is continually directed towards a point at the center of the circle, then the flat board will round the corner in a circular-like path. The ball on the other hand will continue to move in the same direction since there is no unbalanced force acting upon it. The board will move out from under the tennis ball. This is illustrated in the animation on the right.