This creates even stronger lift and the plane leaves the ground. Rotation speed, abbreviated VR, is one of three important airspeed settings calculated before every flight. Some of the factors affecting VR and V2 are the weight of the aircraft, the air temperature and the altitude of the airport. The heavier the aircraft, the more lift, and thus speed is needed to get it off the ground. Aircraft also need to go faster to fly on a hot day than on a cool day.
Hot air is less dense than cool air and less density produces less lift for the same speed.
Similarly, the higher the altitude, the less dense the air. Aircraft need more speed to leave the ground at a place like Denver than at a place like New York, with all other factors such as weight being equal. Some of these factors also are important in calculating V1, although the key factor is the length of the runway that is being used. Most large jets leave the ground at about 160 miles per hour and initially climb at an angle in excess of 15 degrees. The angle of a plane's wings to the air flowing around them is extremely important to maintaining lift.