Dance is a type of sport that usually involves body movement, often performed to different types of music depending on the style. Dance is practiced in many cultures as a form of expression or social relationship in a spiritual or entertainment context, and is also used to express certain beliefs and ideas. Dance has no traceable roots and it is not possible to say when exactly dance became part of the culture, but historical evidence shows that dance has been an important aspect of rituals, services, festivals and entertainment since ancient developments. Ever since dance was discovered, it has become prevalent. Many different dance forms and styles are used around the world today, including ballet, swing, hip-hop, and even tango and salsa. Dance isn't just spinning and jumping; Balance is also a fundamental aspect in any dance style. For balance, in physical terms, the net force and net torque are zero, otherwise the dancer's momentum would change and he or she might fall or tip over. The overall force causes the change in the dancer's momentum and is composed of gravity, floor support, and floor friction. Torque is defined as one or more off-center forces that can cause the dancer to spin. Newton's third law states that for every force there is an equal and opposite force in the opposite direction. A dancer is involved in many motionless poses and in these cases the sum of all torques and forces must be zero. The force pushing up from the floor must cancel out the force of gravity pushing down towards the dancer's foot. If this did not happen, the dancer would accelerate towards the floor causing him to fall. The sum of the forces is zero and both forces point... to the center of the paper... The gravitational force depends on mass and if, for example, the gravitational force is more massive then there is a greater gravitational pull. The net effect of gravity is the same as if it acted only at the dancer's center of gravity. Gravity affects only the vertical component of movement, not the horizontal one. Similar to the height/time graph, the dancer's trajectory in a jump is also a parabola. If the dancer jumps so that the center of gravity rises two feet and the horizontal speed is 10 ft/sec, the path will look like this. To find the average speed of an object, the total distance traveled by the object or dancer in the time it takes to get there. For example, if a dancer moves five meters to the left of the stage in fifteen seconds, the equation would be velocity=5 m/15 s. Consequently, the average speed would be 0.3 m/s.