ASRJC Kinematics Notes

ANDERSON SERANGOON JUNIOR COLLEGE PHYSICS 9749 / 8867 2-1 Additional Notes Topic 2: Kinematics Content: • Rectilinear motion • Non-linear motion Learning Outcomes Candidates should be able to: (a) show an understanding of and use the terms distance, displacement, speed, velocity and acceleration. (b) use graphical methods to represent distance, displacement, speed, velocity and acceleration. (c) identify and use the physical quantities from the gradients of displacement -time graphs and areas under and gradients of velocity-time graphs, including cases of non- uniform acceleration. (d) derive, from the definitions of velocity and acceleration, equations which represent uniformly accelerated motion in a straight line. (e) solve problems using equations which represent uniformly accelerated motion in a straight line, including the motion of bodies falling in a uniform gravitational field without air resistance. (f) describe qualitatively the motion of bodies falling in a uniform gravitational field with air resistance. (g) describe and explain motion due to a uniform velocity in one direction and a uniform acceleration in a perpendicular motion.

ANDERSON SERANGOON JUNIOR COLLEGE PHYSICS 9749 / 8867 2-2 Additional Notes Introduction Kinematics is the branch of mechanics which deals with the description of the motion of bodies. In this chapter, two types of motion will be covered, namely, • along a straight line (rectilinear motion), and • on a plane (non-rectilinear motion). A Terms of Reference for Kinematics A.1 Distance and Displacement • Distance is a scalar quantity while displacement is a vector quantity. • Distance refers to the length of the path travelled by a body regardless of the direction of motion. • Displacement is the distance of a body or a point, in a sp ecified direction, from reference point. Check Your Understanding 1 When displacement of a body is zero, the distance travelled by the body must be zero. (True / False) A.2 Speed and Velocity Speed is a scalar quantity while velocity is a vector quantity. Direction of the velocity is the same as the direction of the change in displacement. Definition: Speed is distance travelled divided by the time taken. Definition: Velocity is the rate of change of displacement. memorise memorise Distance Displacement Demonstrating Science Inquiry Skills The study of kinematics begins with the introduction of precise terminology and language for describing motion, to reduce ambiguity in expression and confusion in thought. Using multiple representations such as motion diagrams, graphs and equations, we can express motion of objects.

ANDERSON SERANGOON JUNIOR COLLEGE PHYSICS 9749 / 8867 2-3 Additional Notes A.3 Instantaneous Speed and Velocity versus Average Speed and Velocity Both average speed and average velocity are measured over a time interval t.