Exercise : Solution of Questions on page Number : 08 Answer : 1 The speed of light in vacuum is 299,792,458 m/s. Then time taken by light to cover a distance of 1 metre in vacuum = 1299, 792, 458 s Hence, the metre is defined as the distance travelled by light in 1299, 792, 458 s. As 300,000,000 m/s is an approximate speed … Read more
Exercise : Solution of Questions on page Number : 321 Answer: 1 No, in wave motion there is no actual transfer of matter but transfer of energy between the points where as when wind blows air particles moves with it. Answer: 2 It is a non-mechanical wave because this type of wave does not require … Read more
Exercise : Solution of Questions on page Number : 270 Answer: 1 Density is defined as mass per unit volume. It tells how closely packed are the molecules inside an object. When molecules are tightly packed, we say that the object is dense; when molecules are far apart, we say that the object is light. … Read more
Exercise : Solution of Questions on page Number : 250 Answer: 7 The mean position of a particle executing simple harmonic motion is fixed, whereas its extreme position keeps on changing. Therefore, when we use stop watch to measure the time between consecutive passage, we are certain about the mean position. Answer: 8 Figure (a) … Read more
Exercise : Solution of Questions on page Number : 223 Answer: 1 A particle will be in equilibrium when the net force acting on it is equal to zero. Two particles under the action of their mutual gravitational force will be in equilibrium when they revolve around a common point under the influence of their … Read more
Exercise : Solution of Questions on page Number : 192 Answer: 1 Yes, such motion is possible if the translation takes place along the axis of rotation. This type of motion is called screw motion. Answer: 2 Yes, it is an example of pure rotation. The axis of rotation passes through the pivot of the … Read more
Exercise : Solution of Questions on page Number : 156 Answer: 1 Yes, the centre of mass can be at a point outside the body. For example, the centre of mass of a ring lies at its centre, which is not a part of the ring. Answer: 2 Yes, if all the particles of a … Read more
Exercise : Solution of Questions on page Number : 130 Answer: 1 No. Work done in lifting the box increases the potential energy of the box. During lifting at every point, the force applied by us on the box in the upward direction is equal to the gravitational force acting on the box in the … Read more
Exercise : Solution of Questions on page Number : 351 Answer: 1 No, we cannot hear the sound of stones. Sound is a mechanical wave and requires a medium to travel; there is no medium on the moon. No, we cannot hear the sound of our own footsteps because the vibrations of sound waves from … Read more
Exercise : Solution of Questions on page Number : 379 Answer: 1 White light is a composition of seven colours. These are violet, indigo, blue, green, yellow, orange and red, collectively known as VIBGYOR. Spectrum of white light consists of sever colour bands. Each band consists of some range of wavelengths or frequencies. For orange … Read more