... We are talking a tangent on a circle that is changing every second.<p>So that is a change of velocity, which is acceleration.  Outwards is clearly &quot;out&quot; of the circle.  The tangent (on the curve) would be a snapshot of that &quot;outward&quot; velocity.<p>As a said: Tangential velocity is the same as saying outward acceleration.  Unless you were referring to just that single &quot;snapshot&quot; in a frozen time scenario.<p>That &quot;outward&quot; force usually comes from a massive rocket... It is then maintained by the inward force of gravity.