Example 9.13 A car of mass 1000 kg travelling at \( 36 \mathrm{~km} / \mathrm{h} \) is brought to rest by applying brakes. Calculate the distance travelled by the car before coming to rest, if the frictional force between the twheels and the road is 2000 N . Solution

एक सरल आवर्ती दोलक की गतिज ऊर्जा 10 Hz की आवृत्ति दोलित होती है । दोलक एक चरम स्थिति से दूसरी स्थिति तक कि समय लेगा? \( \begin{array}{llll}\text { (1) } 0.1 \mathrm{~s} & \text { (2) } 0.2 \mathrm{~s} & \text { (3) } 0.4 \mathrm{~s} & \text { (4) } 0.5 \mathrm{~s}\end{array} \)

Ответ: 2,4 13 Небольшой предмет расположен на главной оптической оси тонкой собираюшей линзы с фокусным расстоянием 20 cm . Расстояние от линзы до предмета составляет 40 cm . Определите расстояние от линзы до изображения предмета. Ответ:

4) Suppose a uniform electric field exists in the room in which you are working, suc at the lines of force are horizontal and at right angles to one wall. As you walk towar e wall from which the lines of force emerge into the room, are you walking toward Points of lower potential Points of the same potential (equipotential line)? All Choices Are Wrong 5) Which of these statements is not characteristic of a static magnetic field? It is solenoidal. Magnetic flux lines are always closed. It has no sinks or sources All Choices Are Wrong

3) One of the following is not a source of magnetostatic fields: A dc current in a wire An electric field linearly changing with time A permanent magnet A charged disk rotating at uniform speed

2) By saying that the electrostatic field is conservative, we do not mean that All Choices Are Wrong The potential difference between any two points is zero. lts circulation is identically zero. Its curl is identically zero. It is the gradient of a scalar potential.