1.When a particle in a circle,a force acts on it directed to

1.When a particle in a circle,a force acts on it directed toward the center of rotation.why is it that this foece does on the particle?
2.when a punter kicks a football ,is he doing any work on the ball while his toe is in contact with it?Is he doing any work on the ball after it loses contact with his toe?Are any forces doing work on the ballwhile it is in flying?
3.As asimple pendulum swings back and forth,the forces acting on the suspended object are the gravitational force,the tension in the supporting cord,and air resistance.(a)Which of this forces,if any,does no work on the pendulum?(b)Which of this negative at all times during the pendulum‘s motion?(c)Describe the work down by the gravitational while the pendulum is swinging.
4.One bullet has twice the mass of a second bullet.If both are fired that they have the same speed,which has more kinetic energy?What is the ratio of the kinetic energies of the two bullets?
5.(a)If the speed of a particle is doubled