Motion
Synopsis
- Rest and motion: If the object's position does not change with respect to time and surroundings, it is said to be at rest. If the position of an object changes with time and surroundings, it is said to be in motion.
- Displacement: The change in the position of a particle during a time interval is called its displacement in that time interval.
- Scalar quantity: A quantity that has only magnitude but no direction is called a scalar quantity, e.g., distance, speed, etc.
- Vector quantity: A quantity that has both magnitude and direction is called a vector quantity, e.g., displacement, velocity, etc.
- Speed: The speed of an object is the distance traversed by it in a given interval of time.
- Average speed :The average speed of a body for the complete journey is given by:
\[Average\,\,\,speed=\frac{Total\,\,dis\tan ce}{Total\,\,time\,\,taken}\]
- Uniform speed: lf an object covers equal distances in equal intervals of time (however small the time intervals maybe), it is said to be moving with a uniform or constant speed.
- Velocity of an object is the speed of the object as well as the direction of its motion. Velocity changes if either speed or the direction of motion changes.
- Acceleration of a moving object is the change in its velocity per unit time.
- Distance-time graph of an object moving with uniform speed is a straight line.
- Velocity-time graph: If an object moves with a constant acceleration in a straight line, its velocity-time graph is a straight line.
- Circular motion: A particle moving in a circular path changes its direction continuously and hence, it is in acceleration. The speed of a body in circular motion may be constant but the velocity is never constant because of the constant change in direction.
- Mathematical equations:\[S=vt\] (S is the distance, v is the speed, t is the time) \[V=u+at\] (u is the initial velocity, v is the final velocity, a is the acceleration (assumed/constant)).
\[S=ut+\frac{1}{2}a{{t}^{2}}\]
\[{{V}^{2}}={{u}^{2}}+2aS\]
Where \['v','u','s'\] and 'a' have their usual meanings.
