DPS GUWAHATI



Class IXName of Chapter: GravitationWeek22 :19th October to 25th October ,2020Periods 1&2: Pg no.131 to 134Step – IStudy the following topic from textbook:Gravitation (Topic 10.1)Universal law of Gravitation (Topic 10.1.1)Importance of the Universal Law of Gravitation (Topic 10.1.2)Step – IIStudy the same topic in the Extramark app.Step – IIIClear your doubts (if any) from your subject teacherStep – IVRevise using the following Bullet points:Gravitation: Earth attracts everything towards it by an unseen force of attraction. This force of attraction is known as gravitation or gravitation pull.3168650311150Universal Law of Gravitation: Every object in the universe attracts every other object by a force of attraction, called gravitation, which is directly proportional to the product of masses of the objects and inversely proportional to the square of distance between them. This is called Law of Gravitation or Universal Law of Gravitation. F = G Mm d2where F = Force of gravitation M = mass of the first object m = mass of the second object d = distance between the centres of the 2 objects G = Universal gravitational constant.Importance of Universal Law of Gravitation:This Law is applicable to every object in the universe.This law explains the cause of revolution of moon around earth and revolution of planets around sun.The gravitational force of the Earth is responsible to hold atmosphere around the earth.Constant:The value of G remains same through the universe and hence G is known as Universal Gravitational Constant.Value of G = 6.67 X 10-11 Nm2 kg-2Value of G was determined in laboratory by Henry Cavendish.Since the value of G is very small, so the gravitational force is a very weak force.Step – VAnswer the following questions in Physics class work copy:How does the force of gravitation between two objects change when the distance between them is reduced to half?What happens to the force between two objects, if the mass of one object is doubled? the distance between the objects is doubled and tripled? the masses of both objects are doubled? What is the magnitude of the gravitational force between the Earth and a 1 kg object on its surface? (Mass of the Earth is 6 × 1024 kg and radius of the Earth is 6.4 × 106 m).The Earth and the Moon are attracted to each other by gravitational force. Does the Earth attract the Moon with a force that is greater or smaller or the same as the force with which the moon attracts the earth? Why? If the Moon attracts the Earth, why does the Earth not move towards the Moon?End of Periods – 1&2TestStep – IRevise the above-mentioned bullet points for 15 minutes.Step – IIFull Marks: 10Answer the following questions: State the law Universal law of Gravitation. (1)Why is the Law of Gravitation called a Universal Law? (1) The gravitational force between two objects is 100 N. How should the distance between the objects be changed so that the force between them becomes 50 N. (2) Derive the formula for the gravitational force using factors on which it depends. (2) Calculate the gravitational force on a stone of mass 1kg held on the surface of the Earth. (2)Calculate the force exerted by the Sun on the Earth, if the mass of the Earth is 6X1024kg, the mass of the Sun is 2X1030kg and the distance between the Sun and the Earth is 1.5X1011m (2)End of 22nd Week ................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download