Physics Class 9 Chapter 3 - Dynamics

What is the branch of mechanics called that deals with the study of motion of an object and the cause of its motion? Dynamics is the branch of.................? How can we open the door? A batsman can change the direction of a moving ball by pushing it with his..........? Whose laws of motion are of fundamental importance in understanding the causes of motion of a body? Which law states that “To every action there is always an equal but opposite reaction”?