An object is said to be in state of motion if its position changes with the passage of time. If the position of the object does not change with the passage of time then the object is said to be at rest. We have now define what is motion and to describe it we consider simplest form of motion that is motion of any object in one dimension for example car moving on the road. To determine the position of car at different times , we could measure its distance from starting point and record all these observations. These observations can be recorded in form of a table or we can draw a distance versus time graph for the motion of the car and see how it is moving.
CBSE Scince Sample Papers 2012 for Class 12
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Acceleration in a curvilinear motion
The acceleration vector has the same direction as instantanous change in velocity. Since the direction of the velocity changes in the direction in which the curve bends ,the acceleration is always pointing towards concavity of the curve
The acceleration in curvilinear motion can also be expressed in terms of two components
How to use Gauss’s Law to find electric field
We all know that Gauss’s law is basically the relation between the charge distribution producing the electrostatic field to the behaviour of electrostatic field in space. Also Gauss’s law is based on the fact that flux through any closed surface is a measure of total amount of charge inside that surface and any charge outside that surface would not contribute anything to the total flux.
Advantages and disadvantages of A.C. over D.C.
ADVANTAGES
The generation of A.C. is cheaper than that of D.C.
A.C. machines are simple , robust and do mot require much attention for their repairs and maintainance during their use.
Wide range of voltages are obtained by the use of transformer.
Wave velocity in a continuous system
Any system whose particle motion are governed by classical wave equation is a system in which harmonic waves of any wavelength can travel with the speed v
The value of v depends on the elastic and inertial properties of the system under consideration.
(1) Transverse wave on a stretched string
Displacement of the string is governed by the equation
Crystals
Many materials like carbon can exist in various forms for example it can exist as diamond in solid form and graphite is also one form of carbon and clearly dimond and graphite have different mechanical, thermal, optical and electrical properties. These properties of different forms of carbon can be understood in terms of carbon atoms in the solid structure.