{"id":7814,"date":"2023-12-13T15:24:25","date_gmt":"2023-12-13T09:54:25","guid":{"rendered":"https:\/\/onlitutor.com\/courses\/lab-manual-science-class-8-cbse\/lesson\/viva-questions-3\/"},"modified":"2023-12-13T15:24:25","modified_gmt":"2023-12-13T09:54:25","slug":"viva-questions-3","status":"publish","type":"lesson","link":"https:\/\/onlitutor.com\/courses\/lab-manual-science-class-8-cbse\/lesson\/viva-questions-3\/","title":{"rendered":"Viva Questions"},"content":{"rendered":"<p><strong>Q: What is friction?<\/strong><\/p>\n<p>A: Friction is a force that opposes the relative motion between two surfaces in contact.<\/p>\n<p><strong>Q: What factors does the force of friction depend on?<\/strong><\/p>\n<p>A: The force of friction depends on the nature of the surfaces in contact.<\/p>\n<p><strong>Q: What is combustion?<\/strong><\/p>\n<p>A: Combustion is a chemical process in which a substance reacts with oxygen to give off heat and light.<\/p>\n<p><strong>Q: What do you mean by ignition temperature?<\/strong><\/p>\n<p>A: The lowest temperature at which a substance catches fire is called its ignition temperature.<\/p>\n<p><strong>Q: What causes friction?<\/strong><\/p>\n<p>A: Friction is caused by the irregularities on the two surfaces in contact.<\/p>\n<p><strong>Q: Does frictional force act even when there is a very smooth surface? How does it happen?<\/strong><\/p>\n<p>A: Yes, even when the surface is smooth, the frictional force is present due to the presence of a large number of minute irregularities on it.<\/p>\n<p><strong>Q: Describe how the force of friction acts between surfaces.<\/strong><\/p>\n<p>A: All surfaces have minute irregularities on them. These irregularities on the two surfaces lock into one another, and when we attempt to move anything over a surface, we have to apply a force to overcome these interlockings. Thus, the force of friction acts upon the surfaces.<\/p>\n<p><strong>Q: Is friction the same for all surfaces?<\/strong><\/p>\n<p>A: No, friction is not the same for all surfaces. Rough surfaces have more friction than smoother ones.<\/p>\n<p><strong>Q: Explain how friction is an essential evil.<\/strong><\/p>\n<p>A: Friction is essential as it allows us to write with a pen or pencil, prevents objects from moving endlessly, and enables the construction of buildings. However, it is also considered an evil as it causes wear and tear of materials.<\/p>\n<p><strong>Q: Which force of friction acts in the opposite direction of motion?<\/strong><\/p>\n<p>A: The force of friction acts in the opposite direction of motion.<\/p>\n<p><strong>Q: Which substance is used to reduce friction?<\/strong><\/p>\n<p>A: Lubricant is used to reduce friction.<\/p>\n<p><strong>Q: Which of the following is not a property of friction?<\/strong><\/p>\n<p>A: Friction does not depend on how hard the two surfaces are pressed together.<\/p>\n<p><strong>Q: Which type of friction has the least force?<\/strong><\/p>\n<p>A: Rolling friction has the least force.<\/p>\n","protected":false},"comment_status":"open","ping_status":"closed","template":"","_links":{"self":[{"href":"https:\/\/onlitutor.com\/index.php\/wp-json\/wp\/v2\/lesson\/7814"}],"collection":[{"href":"https:\/\/onlitutor.com\/index.php\/wp-json\/wp\/v2\/lesson"}],"about":[{"href":"https:\/\/onlitutor.com\/index.php\/wp-json\/wp\/v2\/types\/lesson"}],"replies":[{"embeddable":true,"href":"https:\/\/onlitutor.com\/index.php\/wp-json\/wp\/v2\/comments?post=7814"}],"wp:attachment":[{"href":"https:\/\/onlitutor.com\/index.php\/wp-json\/wp\/v2\/media?parent=7814"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}