kinetic air pump

例句：

1. 1.The kinetic energy of the projectile is proportional to its mass and velocity.
   投射物的动能与其质量和速度成正比。
2. 2. The kinetic friction between the two surfaces is responsible for the wear and tear on the bearings.
   两个表面之间的动摩擦力是轴承磨损的主要原因。
3. 3. The kinetic energy of a ball bouncing off the wall can be calculated using the equation E = 1/2 m v^2, where E is the kinetic energy, m is the mass of the ball, and v is its velocity.
   一个球反弹到墙上时，其动能可以通过公式E = 1/2 m v^2来计算，其中E是动能，m是球的质量，v是球的速度。