It's always opposing the velocity, so this is the magnitude of the resistive force.

总是和速度相反，这是阻力的大小。

youdao

Because the speed increases, so the resistive force will grow, and there comes a time that the two are equal.

因为速度的增加，所以阻力在增大，在某，一时段，这两个力相同。

youdao

If an object moves through a medium — - air or a liquid — there is a resistive force which always opposes the velocity.

如果物体通过媒介-，比如说空气或者液体-，都会遇到阻力，阻力总是和速度相反。

youdao