Lesson Archives

  1. Page No 268: Question 10.1: Explain why (a) The blood pressure in humans is greater at the feet than at the brain (b) Atmospheric pressure at a height of about 6 km decreases to nearly half of its value at the sea level, though the height of the atmosphere is more than 100 km (c) […]
  2. Page No 242: Question 9.1: A steel wire of length 4.7 m and cross-sectional area 3.0 × 10–5 m2 stretches by the same amount as a copper wire of length 3.5 m and cross-sectional area of 4.0 × 10–5 m2 under a given load. What is the ratio of the Young’s modulus of steel to […]
  3. Page No 201: Question 8.1: Answer the following: (a) You can shield a charge from electrical forces by putting it inside a hollow conductor. Can you shield a body from the gravitational influence of nearby matter by putting it inside a hollow sphere or by some other means? (b) An astronaut inside a small space […]
  4. Page No 178: Question 7.1: Give the location of the centre of mass of a (i) sphere, (ii) cylinder, (iii) ring, and (iv) cube, each of uniform mass density. Does the centre of mass of a body necessarily lie inside the body? Answer: Geometric centre; No The centre of mass (C.M.) is a point where […]
  5. Page No 134: Question 6.1: The sign of work done by a force on a body is important to understand. State carefully if the following quantities are positive or negative: (a) work done by a man in lifting a bucket out of a well by means of a rope tied to the bucket. (b) work […]
  6. Page No 109: Question 5.1: Give the magnitude and direction of the net force acting on (a) a drop of rain falling down with a constant speed, (b) a cork of mass 10 g floating on water, (c) a kite skillfully held stationary in the sky, (d) a car moving with a constant velocity of […]
  7. Page No 85: Question 4.1: State, for each of the following physical quantities, if it is a scalar or a vector: volume, mass, speed, acceleration, density, number of moles, velocity, angular frequency, displacement, angular velocity. Answer: Scalar: Volume, mass, speed, density, number of moles, angular frequency Vector: Acceleration, velocity, displacement, angular velocity A scalar quantity […]
  8. Page No 55: Question 3.1: In which of the following examples of motion, can the body be considered approximately a point object: (a) a railway carriage moving without jerks between two stations. (b) a monkey sitting on top of a man cycling smoothly on a circular track. (c) a spinning cricket ball that turns sharply […]
  9. Page No 35: Question 2.1: Fill in the blanks (a) The volume of a cube of side 1 cm is equal to…..m3 (b) The surface area of a solid cylinder of radius 2.0 cm and height 10.0 cm is equal to … (mm)2 (c) A vehicle moving with a speed of 18 km h–1covers….m in […]
  10. Sum of probabilities Thus, the assignment is valid. (b) ω1 ω2 ω3 ω4 ω5 ω6 ω7 Here, each of the numbers p(ωi) is positive and less than 1. Sum of probabilities Thus, the assignment is valid. (c) ω1 ω2 ω3 ω4 ω5 ω6 ω7 0.1 0.2 0.3 0.4 0.5 0.6 0.7 Here, each of the […]