Dance is a type of sport that usually involves movements of the body, often performed to different types of music depending on the style. Dance is practiced in many cultures as a form of expression or social relationships in a spiritual or performance setting, and is even used to express certain beliefs and ideas. The dance has no traceable roots and it is not possible to say exactly when dance became an integral part of the culture, but historical evidence shows that dance has been an important aspect of rituals, services, revelry and entertainment since ancient developments. Since the dance was discovered, it has spread. Many dance forms and styles are used all over the world today, including ballet, swing, hip-hop, and even tango and salsa. Dancing isn't just about spinning and jumping; balance is also a key 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 they could fall or tip. The net force causes the change in the dancer's momentum and includes gravity, ground support, and floor friction. Torque is defined as one or more off-center forces that can turn the dancer. 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 still poses and in these cases the sum of all torques and forces must equal zero. The force pushing upward from the floor must cancel out the force of gravity pulling downward toward the dancer's foot. If this did not happen, then the dancer would accelerate towards the ground, causing him to fall. The forces sum to zero and both forces point...... middle of paper ...... The gravitational force depends on mass and if, for example, the gravitational force is more massive, then there is a greater gravitational attraction. The net effect of gravity is the same as if it were acting only on the dancer's center of gravity. Gravity only influences the vertical component of movement, not the horizontal. Similar to the height/time graph, the trajectory of the dancer during a jump is also a parabola. If the dancer jumps so that the center of gravity rises two feet and the horizontal velocity 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 over the time it took to get there. For example, if a dancer moves five meters to the left of the stage in fifteen seconds, then the equation would look like speed = 5 m/15 s. Consequently, the average speed would be equal to 0.3 m/s..