CBSE ADDA

Q.1. Can any object have mechanical energy even if its momentum is zero? Explain. Yes, mechanical energy comprises of both potential energy and kinetic energy. Zero momentum means that velocity is zero. Hence, there it no kinetic energy but the object may possess potential energy. Q.2. The potential energy of a body is 39600J. How high is the body if its mass is 20kg? The potential energy of a body = mgh h = PE/mg = 39600j/20kg x9.8m/s 2 =198m Q.3. A force of 20 N displaces a body through a distance of 1 m at an angle of 60° from its own direction. Calculate the amount of work done. Here, force F = 20 N, displacement, s = 1 m. Angle between force and displacement 60°. Work done,W =Fscos0 =20 X 1 X cos60°=20X 1 X 1/2 = 10J. A man of 50 kg jumps up to a height of 1.2 m. What is his potential energy at the highest point? The potential energy of man = mgh = = 50 + 10 X 1.2 J = 600 J Q.4. How much work is done by a force of 10 N in moving an object through a distance o

Sample Question Papers English Communicative (Class IX) English Language and Literature (Class IX) English Communicative (Class X) Exam specifications English Communicative (Class X) Sample Paper English Language and Literature (Class X) Hindi A & B (Class X) Sanskrit (Class X) Hindi A & B (Class IX) Sanskrit (Class IX) Social Science (Class X) Social Science (Class IX) Mathematics (Class X) Mathematics (Class IX) Science (Class X) Science (Class IX) Elements of Book Keeping & Accountancy (Class X) Elements of Book Keeping & Accountancy(Class IX) Elements of Business (Class IX) Elements of Business (Class X) Punjabi (Class IX) German (Class IX) Japanese (Class IX) Russian (Class IX) Spanish (Class IX) Persian (Class IX) French (Class IX) Ur

     Measurement and Motion   :Quest Time 1. Name one object that shows multiple motions? Ans: The Earth - Rotatory and translator motion Drilling - Rotatory and downward translator motion A ball moving along the ground- Rotatory and Rectilinear motion      2. How will you measure length in SI system? Ans: Using meter scale 3. What is the quantity that can be measured? Ans: Physical quantity like mass, length and Time 4. What type of motion body moves as a whole? Ans: Translatory motion 5.Which kind of motion produce sound? Ans: Vibratory motion 6. What types of motion is noticed in the pendulum of clock and swing? Ans: Oscillatory motion and periodic 7.  Falling of apple from tree is what types of motion? Ans: Rectilinear motion. 8. Discovery of what made transport easy? Ans: Wheel 9. Motion in which the distance from the axis remain same? Ans: Circular motion 10. To and fro motion of a body about a fix point is example of

1. Out of convex mirror and concave mirror, whose focus is situated behind the mirror ? Ans: The focus of convex mirror is situated behind it. 2. For what position of an object, a concave mirror forms an enlarged virtual image? Ans: Object between pole (P) and focus (F) of the concave mirror. 3. If the focal length of a concave mirror is 25cm. What is its radius of curvature? Ans: Focal length = Radius of curvature / 2 25 = R / 2 R = 25 X 2 = 50cm. 4. A ray of light falls on a mirror normally. What are the values of angle of incidence and the angle of  reflection? Ans: Both angle of incidence and the angle of reflection are zero. 5. What is the focal length of a plane mirror? Ans: Infinite. 6. Which spherical mirror is called a divergent mirror? Ans: A convex mirror is called a divergent mirror. 7. What is the angle of incidence, when a ray of light falls on the spherical mirror from its centre of curvature? Ans: The angle of incidence is zero, when a ra