{"id":4626,"date":"2020-08-28T10:43:31","date_gmt":"2020-08-28T05:13:31","guid":{"rendered":"https:\/\/kseebsolutions.guru\/?p=4626"},"modified":"2021-07-02T15:04:06","modified_gmt":"2021-07-02T09:34:06","slug":"kseeb-solutions-class-8-science-chapter-8","status":"publish","type":"post","link":"https:\/\/kseebsolutions.guru\/kseeb-solutions-class-8-science-chapter-8\/","title":{"rendered":"KSEEB Solutions for Class 8 Science Chapter 8 Describing Motion"},"content":{"rendered":"<h2>Karnataka Board Class 8 Science Chapter 8 Describing Motion<\/h2>\n<h3>KSEEB Class 8 Science Chapter 8 Textual Questions &amp; Answers<\/h3>\n<p>I. Four alternatives are given to each of the following incomplete statement\/ question, choose the right answer.<\/p>\n<p>Question 1.<br \/>\nUniform circular motion is called continuously accelerated motion mainly because<br \/>\n(a) direction of motion changes<br \/>\n(b) Speed remains the same<br \/>\n(c) Velocity remains the same<br \/>\n(d) direction of motion does not change<br \/>\nAnswer:<br \/>\na) direction of motion changes<\/p>\n<p>Question 2.<br \/>\nA cricketer hits a sixer, the cricket ball moves up with a velocity of 2 ms<sup>-1<\/sup> and falls down. Its initial velocity while falling down will be<br \/>\na) 1 ms<sup>-1<br \/>\n<\/sup>b) 1 ms<sup>-2<\/sup><br \/>\nc) 0 ms<sup>-1<\/sup><br \/>\nd) 2 ms<sup>-1<\/sup><br \/>\nAnswer:<br \/>\nc) 0 ms<sup>-1<\/sup><\/p>\n<p>II. Fill in the blanks with suitable words:<\/p>\n<p>Question 1.<br \/>\nS.I. unit of acceleration is &#8230;&#8230;&#8230;&#8230;.<br \/>\nAnswer:<br \/>\nmeter per second<sup>2<\/sup>\/ms<sup>-2<\/sup><\/p>\n<p>Question 2.<br \/>\nVelocity has both speed and &#8230;&#8230;&#8230;.<br \/>\nAnswer:<br \/>\ndirection<\/p>\n<p>Question 3.<br \/>\nIf an object starts from A and comes back to A. It displacement will be &#8230;&#8230;&#8230;&#8230;.<br \/>\nAnswer:<br \/>\n(0) zero<\/p>\n<p>III. Solve<\/p>\n<p>Questions 1.<br \/>\nAn object is moving in a circular path of radius 3.5 m. If completes one full cycle, what will be the displacement and what is the distance traveled?<br \/>\nAnswer:<br \/>\nradius = 3.5 m<br \/>\nstarting point is A and ending point also A.<br \/>\nthe displace = 0<br \/>\nDistance traveled = \u03c0 \u00d7 3.5 \u00d7 2<br \/>\n<img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/live.staticflickr.com\/65535\/48107320178_be36ce6485_o.png\" alt=\"KSEEB Solutions for Class 8 Science Chapter 8 Describing Motion iii-1\" width=\"292\" height=\"81\" \/><br \/>\nQuestion 2.<br \/>\nAn object changes its velocity from 30 ms<sup>-1<\/sup> to 40 ms<sup>-1 <\/sup>in a time interval of 2 seconds what is its acceleration?<br \/>\nAnswer:<br \/>\nu = 30 ms<sup>-1<\/sup><br \/>\nv = 40 ms<sup>-1<\/sup><br \/>\nt = 2 sec<br \/>\na = ?<br \/>\n<img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/live.staticflickr.com\/65535\/48107282996_283310e71c_o.png\" alt=\"KSEEB Solutions for Class 8 Science Chapter 8 Describing Motion iii-2\" width=\"355\" height=\"70\" \/><br \/>\nQuestion 3.<br \/>\nAn object at rest starts moving. It covers a distance of 2 m in one second. It covers a, further distance of 5 m in two seconds in the same direction what is the average velocity and acceleration?<br \/>\nAnswer:<br \/>\ndistance traveled on 1 sec = 2 mts<br \/>\ndistance traveled on 2 sec = 5 mts<br \/>\ntotal distance traveled = 2 + 5 = 7 mts<br \/>\ntotal time taken to cover 7 mts = 1+2 = 3 sec<br \/>\n<img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/live.staticflickr.com\/65535\/48107294296_5c9370451e_o.png\" alt=\"KSEEB Solutions for Class 8 Science Chapter 8 Describing Motion iii-3\" width=\"334\" height=\"71\" \/><br \/>\n= \\(\\frac { 7 }{ 3 }\\) = 2.3 ms<sup>-1<\/sup><br \/>\nAverage velocity = 2.3 ms<sup>-1<br \/>\n<\/sup>s = ut + \\(\\frac { 1 }{ 2 }\\) at<sup>2<br \/>\n<\/sup>7 = 0 \u00a03 +\\(\\frac { 1 }{ 2 }\\) a \u00d7 3<sup>2<br \/>\n<\/sup>7 =0 + \\(\\frac { 1 }{ 2 }\\) a \u00d7 9<br \/>\n= \\(\\frac { 9 }{ 2 }\\) a = 7<br \/>\n9a =7 \u00d7 2 = 14<br \/>\na =\u00a0 \\(\\frac { 14 }{ 9 }\\)\u00a0 = 1.5 ms<sup>-2<\/sup><\/p>\n<p>IV. Answer the following.<\/p>\n<p>Question 1.<br \/>\nIf a body is moving with uniform velocity in a given direction its acceleration will be zero, why?<br \/>\nAnswer:<br \/>\nThe acceleration will be zero in the above situation since there is no change in velocity in unit time.<\/p>\n<p>Question 2.<br \/>\nDistinguish between speed and velocity.<br \/>\nAnswer:<\/p>\n<ol>\n<li>Speed\n<ul>\n<li>Speed is the distance traveled by an object in unit time<\/li>\n<li>Speed = \\(\\frac { distance }{ time }\\)<\/li>\n<li>Speed is a scalar quantity<\/li>\n<li>Speed has the only magnitude<\/li>\n<\/ul>\n<\/li>\n<li>Velocity\n<ul>\n<li>Velocity is the rate of displacement of the body in unit time.<\/li>\n<li>Velocity =\\(\\frac { displacement }{ time }\\)<\/li>\n<li>Velocity is a vector quantity<\/li>\n<li>It has both magnitude and direction.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n<p>Question 3.<br \/>\nDistinguish between distance traveled and displacement.<br \/>\nAnswer:<\/p>\n<ol>\n<li>Distance traveled\n<ul>\n<li>Distance traveled is the length of actual path traveled by a body from one position to another.<\/li>\n<li>It is a scalar quantity<\/li>\n<li>It has an only numerical value<\/li>\n<\/ul>\n<\/li>\n<li>Displacement\n<ul>\n<li>Displacement is the shortest path between initial and final position of the moving body.<\/li>\n<li>It is a vector quantity<\/li>\n<li>If has both numerical value and direction.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n<p>Question 4.<br \/>\nWhat are uniform and non-uniform speed?<br \/>\nAnswer:<\/p>\n<ol>\n<li>If an object covers equal distance in equal intervals of time, it is said to be uniform motion.<\/li>\n<li>non-uniform motion: If an object covers unequal distance in equal intervals of time, it is said to be non uniform motion.<\/li>\n<\/ol>\n<p>Question 5.<br \/>\nWhile mentioning acceleration the time is mentioned two times, why?<br \/>\nAnswer:<br \/>\nVelocity is the rate of displacement of a body in unit time.<br \/>\nV =\\(\\frac { displacement }{ time }\\)<br \/>\nAcceleration is the change in velocity of a body in unit time.<br \/>\n<img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/live.staticflickr.com\/65535\/48107405041_2af0591b0f_o.png\" alt=\"KSEEB Solutions for Class 8 Science Chapter 8 Describing Motion 8-5\" width=\"449\" height=\"120\" \/><br \/>\nWhile mentioning acceleration time is mentioned two times. (Acceleration occurs twice)<\/p>\n<p>V. Extended activity<br \/>\nRepresent the following motion by a graph.<br \/>\n<img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/live.staticflickr.com\/65535\/48107526327_72255b755e_o.png\" alt=\"KSEEB Solutions for Class 8 Science Chapter 8 Describing Motion 8-v\" width=\"446\" height=\"232\" \/><br \/>\nQuestion 1.<br \/>\nFind the acceleration<br \/>\nAns. Acceleration from the graph<br \/>\n= \\(\\frac { 40-10 }{ 4-1 }\\) = \\(\\frac { 30 }{ 3 }\\) = 10 ms<sup>-1<\/sup><\/p>\n<p>Question 2.<br \/>\nFind the time taken when the velocity in 35 ms<sup>-1<\/sup><br \/>\nAnswer:<br \/>\nTime taken to travel a distance of 35 ms<sup>-1\u00a0<\/sup> is 1.5 seconds.<\/p>\n<h3>KSEEB Class 8 Science Chapter 8 Additional Questions &amp; Answers<\/h3>\n<p>Question 1.<br \/>\nDefine motion?<br \/>\nAnswer:<br \/>\nThe change in position of a body with time when compared with that of another body is called motion.<\/p>\n<p>Question 2.<br \/>\nMotion is reflective-substantiate this statement with a suitable example.<br \/>\nAnswer:<br \/>\nImagine that you are sitting inside the train when the train starts moving you a fee that the persons on the platform are moving backward you feel that you and the other persons inside the train are not moving.<br \/>\nBut for a person standing outside the train, the feeling will be that the train, you and the other members inside the compartment are all moving.<\/p>\n<p>Question 3.<br \/>\nAn object travels from A to B and then from B to C as shown in the figure.<br \/>\n1. Find the distance traveled and<br \/>\n2. Find the displacement<br \/>\n3. Write the conclusion<br \/>\nAnswer :<\/p>\n<p><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/live.staticflickr.com\/65535\/48107433196_e9e880e93c_o.png\" alt=\"KSEEB Solutions for Class 8 Science Chapter 8 Describing Motion add-3\" width=\"171\" height=\"109\" \/><br \/>\nLet ABC is a right-angled triangle with B as shown in the actual figure,<\/p>\n<ol>\n<li>If a person travels from A to B and then to C the total distance traveled is = (3 m + 4 m) = 7 mts.<\/li>\n<li>The displacement is the change in position from A to C<br \/>\n<img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/live.staticflickr.com\/65535\/48107583297_fb669257cf_o.png\" alt=\"KSEEB Solutions for Class 8 Science Chapter 8 Describing Motion 8-3\" width=\"293\" height=\"71\" \/><\/li>\n<li>displacement value is lesser than the distance traveled.<\/li>\n<\/ol>\n<p>Question 4.<br \/>\nAn object moves from A to A in a circular path of radius 7 m. What is the distance traveled? What is the displacement?<br \/>\nAnswer:<br \/>\nDisplacement = Diameter = 2 \u00d7 radius = 2 \u00d7 7= 14 m<br \/>\nDistance traveled = \\(\\frac { 1 }{ 2 }\\) \u00d7 circumference<br \/>\n= \\(\\frac { 1 }{ 2 }\\) \u00d7 2 \u00d7 \u03c0 \u00d7 r<br \/>\n= \\(\\frac { 1 }{ 2 }\\) \u00d7 2 \u00d7 \\(\\frac { 22 }{ 7 }\\) \u00d7 7<br \/>\n= 22 m<\/p>\n<p>Question 5.<br \/>\nDefine the following<br \/>\na) Speed<br \/>\nb) Velocity<br \/>\nAnswer:<\/p>\n<ol>\n<li>Speed: is the distance traveled by an object in unit time<\/li>\n<li>Velocity: is the rate of displacement of a body in unit time.<\/li>\n<\/ol>\n<p>Question 6.<br \/>\nAn object is moving in a circular path of radius 7 m. To travel from \u2018A\u2019 to \u2018B\u2019 along the circumference it takes 2 seconds?<br \/>\nAnswer:<br \/>\nData : radius = 7 m<br \/>\ntime = 2 s<br \/>\naverage speed = ?<br \/>\nspeed = \\(\\frac { distance traveled }{ time }\\)<br \/>\n<img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/live.staticflickr.com\/65535\/48107619897_82e31b3b39_o.png\" alt=\"KSEEB Solutions for Class 8 Science Chapter 8 Describing Motion 8-6\" width=\"291\" height=\"157\" \/><br \/>\nQuestion 7.<br \/>\nWhen can we say that speed and velocity are synonyms.<br \/>\nAnswer:<br \/>\nSpeed and velocity will be equal for uniform motions along a straight line. Then it will be one and the same.<\/p>\n<p>Question 8.<br \/>\nWhat is meant by acceleration?<br \/>\nAnswer:<br \/>\nA change in velocity of a body in unit time or the rate of change of velocity is called acceleration.<\/p>\n<p>Question 9.<br \/>\nFor an object moving at a uniform speed in a circular path, though the speed is uniform it is continuously accelerated, why? Give reason.<br \/>\nAnswer:.<br \/>\nFor an object moving in a circular path, the direction is changing at every point even though the speed is the same. Therefore velocity changes and hence it is continuously accelerated.<\/p>\n<p>Question 10.<br \/>\nAn object at rest gains an average velocity of 40 ms-1 in 5 seconds. What will be its acceleration?<br \/>\nAnswer:<br \/>\nIts initial velocity, u = 0<br \/>\nIts final velocity, v = 40 ms<sup>-1<br \/>\n<\/sup>Time taken t = 5 second the<br \/>\nrate of change of velocity<br \/>\n\\(\\frac { 40 }{ 8 }\\) = 8 ms<sup>-2<\/sup><br \/>\nacceleration, a = 8 ms<sup>-2<\/sup><\/p>\n<p>Question 11.<br \/>\nAn object at rest starts moving and attains a velocity of 10 ms<sup>-1 <\/sup>after 5 seconds. What is the acceleration?<br \/>\nAnswer:<br \/>\nInitial velocity, u = 0<br \/>\nFinal velocity, v = 10 ms<sup>-1<\/sup><br \/>\nTime interval, t = 5 second<br \/>\na = \\(\\frac { u-v }{ t }\\) = \\(\\frac { 10 &#8211; 0 }{ 5 }\\) = 2 ms<sup>-2<\/sup><\/p>\n<p>Question 12.<br \/>\nAn object moving with a uniform velocity of 10 ms<sup>-1 <\/sup>comes to rest after 5 seconds. What is the acceleration?<br \/>\nAnswer:<br \/>\nInitial velocity, v = 10 ms<sup>-1<\/sup><br \/>\nFinal velocity, u = 0<br \/>\nTime interval, t = 5 second<br \/>\na = \\(\\frac { u-v }{ t }\\) =\u00a0 \\(\\frac { 0 &#8211; 10 }{ 5 }\\) = &#8211; 2 ms<sup>-2<\/sup><\/p>\n<p>Question 13.<br \/>\nAn object at rest starts moving with a uniform acceleration of 1 ms<sup>-2<\/sup> Calculate the distance traveled by it in 4 seconds.<br \/>\nAnswer:<br \/>\nu = 0<br \/>\na = 1 ms<sup>-2<\/sup><br \/>\nt = 4 second ,<br \/>\nDistance traveled s = ut + \\(\\frac { 1 }{ 2 }\\) at<sup>2<\/sup><br \/>\nS = 0 \u00d7 4 + \\(\\frac { 1 }{ 2 }\\) \u00d7 1\u00a0 \u00d7 4<sup>2<\/sup><br \/>\n=0 + \\(\\frac { 1 }{ 2 }\\) \u00d7 1 \u00d7 16 = 18 m<\/p>\n<p>Question 14.<br \/>\nAn object starts from rest and attains a uniform acceleration of 4 ms<sup>-2<\/sup> what will be its velocity at the end of half a meter?<br \/>\nAnswer:<br \/>\nu = 0<br \/>\na = 4 ms<sup>-2<\/sup><br \/>\ns = \\(\\frac { 1 }{ 2 }\\)<br \/>\nv<sup>2<\/sup> = ?<br \/>\nv<sup>2<\/sup>= u<sup>2<\/sup> + 2as<br \/>\nv<sup>2 <\/sup>= 0<sup>2 <\/sup>+ 2 \u00d7 4<sup>2 <\/sup> \u00d7 \\(\\frac { 1 }{ 2 }\\)<br \/>\nv<sup>2 <\/sup> = 4<br \/>\nv<sup>2<\/sup> = \\(\\sqrt { 4 } \\) = 2 ms<sup>-1<\/sup><\/p>\n<p>Question 15.<br \/>\nWhat is the distance-time graph? What are its uses?<br \/>\nAnswer:<br \/>\nMotion can be represented by a time graph. If it represents time on the x-axis and distance traveled on the y-axis, it is called a distance-time graph.<\/p>\n<p>Uses of the distance-time graph are,<\/p>\n<ol>\n<li>The distance at which the body is at present from its starting point can be found out.<\/li>\n<li>Time taken to cover a definite distance can be determined<\/li>\n<li>Since it is uniform motion speed of the body can also be calculated.<\/li>\n<\/ol>\n<p>Question 16.<br \/>\nWhat do you infer about the velocity when the velocity-time graph is parallel to the x-axis.<br \/>\nAnswer:<br \/>\nThe body is at rest no acceleration.<\/p>\n<p>Question 17.<br \/>\nDefine negative acceleration?<br \/>\nAnswer:<br \/>\nIt is a Negative acceleration as the moving body reduces its velocity due to applied force, denoted by \u201c-a\u201d.<\/p>\n<h4><a href=\"https:\/\/kseebsolutions.guru\/kseeb-solutions-class-8-science\/\"> KSEEB Solutions for Class 8 Science<\/a><\/h4>\n","protected":false},"excerpt":{"rendered":"<p>Karnataka Board Class 8 Science Chapter 8 Describing Motion KSEEB Class 8 Science Chapter 8 Textual Questions &amp; Answers I. Four alternatives are given to each of the following incomplete statement\/ question, choose the right answer. Question 1. Uniform circular motion is called continuously accelerated motion mainly because (a) direction of motion changes (b) Speed &hellip;<\/p>\n","protected":false},"author":5,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/posts\/4626"}],"collection":[{"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/comments?post=4626"}],"version-history":[{"count":0,"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/posts\/4626\/revisions"}],"wp:attachment":[{"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/media?parent=4626"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/categories?post=4626"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/tags?post=4626"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}