NCERT CLASS 11 PHYSICS CHAPTER 4 – LAWS OF MOTION IN-TEXT QUESTIONS AND ANSWERS 1. What is force? Force is an external agent that changes or tends to change the state of rest or uniform motion of a body. It can also change the direction or shape of an object. 2. What is inertia? Inertia is the natural tendency of a body to resist any change in its state of rest or uniform motion in a straight line. 3. What are the three types of inertia? The three types of inertia are: Inertia of rest: The tendency of a body to remain at rest. Inertia of motion: The tendency of a moving body to continue moving with uniform velocity. Inertia of direction: The tendency of a body to resist a change in its direction of motion. 4. State Newton's first law of motion. Newton's first law states that a body continues to remain at rest or in uniform motion along a straight line unless acted upon by an external unbalanced force. 5. What is momentum? Momentum is the product of the mass and velocity of...

  NCERT CLASS 11 PHYSICS CHAPTER 5 – WORK, ENERGY AND POWER IN-TEXT QUESTIONS AND ANSWERS 1. What is work in physics? Work is said to be done when a force acting on a body produces displacement in it. For a constant force: W = F s cos θ Where: W = work done F = applied force s = displacement θ = angle between force and displacement The SI unit of work is joule (J). 2. When is work done by a force positive? Work is positive when the force has a component in the direction of displacement. For example, when a person lifts a bag vertically upwards, the applied force and displacement are in the same direction. W = Fs cos 0° W = Fs 3. When is work done by a force negative? Work is negative when the force acts opposite to the direction of displacement. For example, friction does negative work on a moving body because friction acts opposite to its motion. W = Fs cos 180° W = −Fs 4. When is work done by a force zero? Work done is zero in the following situations: When there is no displaceme...