PHY101 Midterm Lectures 1-22

Lecture no 1

What is Physics?

The branch of science concerned with the nature and properties of matter and energy. The subject matter of physics includes mechanics, heat, light and other radiation, sound, electricity, magnetism, and the structure of atoms.

Define the category of Classical mechanics.

motion of macroscopic a physical theory describing the Classical mechanics is objects.

(OR)

Classical mechanics is the part of physics that describes how everyday things move and how their motion changes because of forces.

Define the category of electromagnetism.

Electromagnetism is a branch of physics involving the study of the electromagnetic force, a type of physical interaction that occurs between electrically charged particles.

Define the category of thermal physics.

Thermal physics is the combined study of thermodynamics, statistical mechanics, and kinetic theory of gases.

Define the category of quantum mechanics.

Science dealing with the behavior of matter and light on the atomic and subatomic scale is known as quantum mechanics

Points to be noted

imp quiz

✓ Every physical quantity can be expressed in terms of three fundamental dimensions: Mass (M), Length (L), and Time (T).

✓ You cannot add quantities that have different dimensions. So force can be added to force, but force can never be added to energy. ➢ Do not confuse units and dimensions. We can use different units to measure the same physical quantity.

✓ Always check your equations to see if they have the same dimensions on the left side as on the right. ✓ MKS stand for Meter Kilogram-Second system Formula

• Area has dimensions of L2 · • Density has dimensions of M / L3 (or ML-3) · • Frequency has dimensions of 1/T · • Speed has dimensions of L/T

Lecture 2 – KINEMATICS I

Function

Position of a body at time t is denoted as x(t) x is called a function of t.

In geometry and mechanics, a displacement is a vector whose length is the shortest distance from the initial to the final position of a point P undergoing motion.

Formula

If a body is moving with average speed v then in time t it will cover a distance d=vt

Speed and Velocity

The velocity of an object is the rate of change of its position with respect to a frame of reference, and is a function of time. Velocity is equivalent to a specification of an object's speed and direction of motion.

Average velocity = total distance traveled total time

Average velocity=

total time x x t t = x t

Acceleration

In mechanics, acceleration is the rate of change of the velocity of an object with respect to time. Accelerations are vector quantities. The orientation of an object's acceleration is given by the orientation of the net force acting on that object.

Constant Acceleration

If the velocity of the particle changes at a constant rate, then this rate is called the constant acceleration.

Formula · x = xo + vot + ½at2 · v = vo + at · Vectors

A vector is an object that has both a magnitude and a direction. Geometrically, we can picture a vector as a directed line segment, whose length is the magnitude