What is the acceleration of a projectile at its highest point? what is the acceleration just before and after the point?

Ignoring effects of air resistance, the acceleration of a projectile near the surface of the earth is -9.8 m/s².  This is true at all points along the trajectory.

conservation of mass

mass before something happens = mass afterwards

the design of a ski jumping suit involves a trade-off between giving the skiers lift to get higher jumps and ensuring the skier does not face a lot of drag before the jump itself. an expansive suit may to lift the skier higher, but at the same time, it will also increase the air resistance. higher air resistance as the skier goes down the slope limits the speed of the jump. a big suit also increases the risk of losing balance or control, especially if there's a strong gust of wind. while technologically enhanced suits a lot, clothing is not the only factor in a ski jumper’s success. gathering speed while skiing down the slope, ensuring good speed on the ramp, and maintaining good body posture and form in the air all contribute to a ski jumper's success.