What is the difference between the initial velocity of slingshots in winter and summer?

40。 Due to the high temperature in summer, the elastic band on the slingshot is soft and can be stretched, which can convert more tension into thrust. In summer, the initial speed is basically 130. In winter, the elastic band is not soft enough and stretched very long, and the initial speed will drop to 90. After calculation, the initial velocity with a difference of 40 can be obtained.