1. If you apply a force to an object only for just and instant, for examples, if you hit a ball with a force of 10 N and it moves 100 meters, are you making work? 2. How can a constant force that is applied to an object during a period of time can make it move with constant speed? According to Newtons second law, F=ma, so the object should accelerate. 3. My teacher says that if we push a pendulum with the exact force it requires to reach its maximum high, the time it will take to reach that point will be infinite. How can this be possible? Thanks in advance.