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 Equilibrium Its States and Conditions of Equilibrium Book Problems 

 Center of Mass or Center of Gravity A body behaves as if its all mass is concentrated at one point called as Center of Mass or Center of Gravity. Even though earth attract every part of it.  Below figure shows center of masses of different shapes. Center of Mass of Irregular Shapes: In case of regular shapes it is easier to find the center of mass because of their structure, but can we find the center of mass of an irregular shape? Yes we can. Following are some steps to find the center of mass of the irregular shapes: Step 01: Make small holes on the edges of the irregular shapes.  Step 02: Suspend the irregular shape one whole retord stand. Step 03: Hung a plumb line or weight from the pin in front of irregular shape. Step 04: When plumb line is steady, trace the line on the irregular shape. Step 05: Repeat step 2-4 for second and third hole.   Couple: A couple is formed by two unlike forces of same magnitude but opposite in direction.  The torque produc...

  Principle of Moments Considering above figure, lets discuss what is principle of moments. The torque or moment of force produced as spanner is subjected to force as shown above in figure part a. The rotation produced will be in Clockwise direction . The torque or moment of force produced as spanner is subjected to force as shown above in figure part b. The rotation produced will be in  Anticlockwise direction . Statement: "A body is balanced if the sum of clockwise moments acting on the body is equal to the sum of anticlockwise moments acting on the body." Sum of clockwise moments = Sum of anticlockwise moments Example: A meter rod is supported at its middle point O as shown in figure 4.15 (refer book). The block of 10N is suspended at point B, 40cm from O . Find the weight of the block that balances it at point A, 25 cm from O. Data: w1= ? w2=10N Moment of arm of w1=OA=25cm or 0.25m Moment of arm of w2=OB= 40cm or 0.40m Solution: According to the Principle of the moments w...

 Torque or Moment of Force The turning effect of the force is called Torque. It is also known as Moment of Force.  Torque depends on: The magnitude of force. The perpendicular distance between point of application of the force and the pivot.  It is also called as Moment Arm. Now considering above equation, we have unit of torque is  Nm. Moments are described as Clockwise or Anti-clockwise in direction. Example Problems on Torque Example 01: A driver tightens the nut of the wheel using 2cm long spanner by exerting a force of 300N. Find the torque. Data: d= 2cm => 2/100= 0.02m F= 300N Torque =? Solution: Torque = F x d Torque = 300 x 0.02 Torque = 6Nm. Self-Assessment Question: What will be the moment of force? When 500N of force is applied on 40cm long spanner to tighten the nut? Data: d= 40cm = 0.4m F=500N Torque =? Solution: Torque = F x d Torque = 500 x 0.4 Torque = 200Nm. Example 02: A mechanic tightens the nut of the bicycle using a 15cm long spanner by exerti...

 DETERMINATION OF FORCE FROM ITS RECTANGULAR COMPONENTS In this method, we are going to find the resultant force, its direction and the magnitude, when its rectangular components are given. Consider the figure given above. Let Fx and Fy are the rectangular/perpendicular components of the force F. Applying Head-to-Tail Rule we get, OR = OP + PR Since,  OR =F OP= Fx PR= Fy so,  F = Fx + Fy For Magnitude of Force: Applying Pythagoras theorem to the above figure we get,            Taking Square root on both the sides. For Direction: The direction of the force (F) with the x-axis can be found as,

 CHAPTER 3 DYNAMICS SECTION A: MULTIPLE CHOICE QUESTIONS

 MOMENTUM IN TERMS OF FORCE                             (    Δp = Ft) Download PPT Lecture Download Now

 NUMERICAL PROBLEMS ON EQUATIONS OF MOTION (EXERCISES + EXAMPLES) Download PPT of the lecture:  Download Now

  SCALAR AND VECTOR QUANTITIES Table of Contents: What are Physical Quantities What are Scalar Quantities What are Vector Quantities PHYSICAL QUANTITIES:                                         Those quantities which can be measured and have a unit are called Physical Quantities. They are divided into two types of quantities Scalar Quantities Vector Quantities Scalar Quantities: Those quantities which are specified by their Magnitude and unit only are termed as Scalar Quantities. Magnitude is nothing but it is a number for instance, 5 kg of sugar. Here 5 is Magnitude and kg is the unit. For Example: Speed Distance Energy Workdone Power Vector Quantities Those quantities which are specified by their magnitude + unit and direction, are called Vector Quantities. For Example: Velocity Acceleration Force Tension Graphical Representation of Vect...

  SOME SOLVED PROBLEMS ON SPEED VELOCITY AND ACCELERATION Hello students in this article I have posted few solved problems on Speed, Velocity and Acceleration.  Example#01: A sprinter completes its 100 meters race in 12 sec. Find its average speed. Solution:               From the given data we have;                              distance = 100 meters                              Time taken = 12 seconds                              Average speed=?               As we know that                          Avg. speed= distance travelled/time taken         ...

  Types of Motion As in previous article I have discussed about the basics of Kinematics, and also discussed about the concept of Rest and Motion. In this article I am going to give you the concept of types of Motion. So there are three types of Motion namely; 1. Translatory Motion 2. Rotatory Motion 3. Oscillatory Motion 1. TRANSLATORY MOTION When all the points of the body moves uniformly along the same straight line, such motion is known as Translatory Motion. For Example:                              A train moving straight on a track is an example of Translatory Motion.      Translatory motion is further classified into; (i) Linear Motion (ii) Circular Motion (iii) Random Motion (i) LINEAR MOTION:                                              ...

 KINEMATICS Mechanics is the branch of Physics, which deals with the study of motion of objects with or without the reference of force. It is divided into two branches: 1. Kinematics 2. Dynamics Kinematics deals with the motion of objects without the reference of the force. Such as: Motion of free fall body. Motion of a car on straight line. Dynamics on the other hand is the study of the motion of objects, with the reference of force. Such as: Motion of cars (Here we basically talk about the forces acting on an engine) Throwing of an object  (When we through an object the force acted/ applied by the muscle being discussed here.) REST AND MOTION A body is said to be in the state of rest, if it does not change its position with respect to its surroundings. For Example:                              When you are sitting in a bus and the bus is moving but you are not changing your position with res...

 SIGNIFICANT FIGURES The value of a physical quantity is expressed by a number followed by some suitable unit. Every measurement of a quantity is an attempt to find its true value. The accuracy in measuring a physical quantity depends upon various factors:  + the quality of the measuring instrument  + the skill of the observer  + the number of observations made For example, a student measures the length of a book as 18 cm using a measuring tape. The numbers of significant figures in his/her measured value are two. The left digit 1 is the accurately known digit. While the digit 8 is the doubtful digit for which the student may not be sure. Another student measures the same book using a ruler and claims its length to be 18.4 cm. In this case all the three figures are significant. The two left digits 1 and 8 are accurately known digits. Next digit 4 is the doubtful digit for which the student may not be sure. A third student records the length of the book a...