You manage to exert a 50Newton force on it. This is the force that the Earth exerts on you. Two teams have a tug of war, in the beginning the match is very even. The team on the right now begins to win because the left team is exhausted and is only pulling half as hard. In a good swivel chair you must push against something to start or stop spinning.
Ice skaters pull their arms in to speed up.
Decreases the moment of inertia. A crackpot inventor friend shows you a bicycle that uses the entire back tire as the rear sprocket, instead of just a small sprocket near the hub. The pedals would require less force but it would go slower. A common pair of pliers has a wire cutter that is close to the pivot point. A speeding locomotive.