Motion Notes

• Mechanics is the branch of Physics that deals with study of objects at rest or under motion in space and time like distance traveled, displacement, velocity, acceleration, speed etc. It also deals with associated causes of motion like force, torque etc.

1. Statics: Branch of mechanics which deals with the study of objects at rest.
2. Kinematics: Branch of mechanics which deals with the study of motion of objects without taking into account the factors which cause motion.
3. Dynamics: Branch of mechanics which deals with the study of motion of objects taking into account the factors which causes motion.

Motion:

• The distance covered by a moving object is the actual length of the path followed by the object, irrespective of the direction in which the body travels.
• So, Distance is a scalar quantity. SI unit of distance is meter.
• Displacement is the shortest distance covered by a moving object from the point of reference (initial position of the body), in a specific direction. i.e., it is a straight line between the initial position and the final position of the body, along with the direction.
• SI unit of displacement is metre.
• Displacement is a vector, i.e., the displacement is given by a number with proper units and direction.

Examples:

• A body has a uniform motion if it travels equal distances in equal interval of time.
• The distance time graph for uniform motion is a straight line.