WEIGHT GRAVITY, MASS, AND WEIGHT OBJECTIVES I. II. Understands that the force of gravity acts between objects. Learn about what affects the strength of the force of gravity on an object. III. Differentiate between mass and weight. Weight is the force of gravity acting on an object. Weight is a force; hence its unit is Newton (N). Weight is measured with spring balance. The weight of a body varies from place to place. It depends on the mass of the object and the gravitational field Strength. Weight (W) = mass (M) X gravitational field strength (g) W=Mxg KEYWORDS: gravity, mass, weight, field strength GRAVITY Gravity is the force that pulls all objects towards each other. It is the reason why objects fall to the ground and why planets orbit around the sun. The force of gravity caused by an object acts towards the center of the earth. The size or strength of the force of gravity between two objects depends on i. ii. The mass of the two bodies, and The distance apart between the two bodies. The more the masses between bodies the more the gravitational force. The more the distance apart between the bodies the lower the gravitational force. MASS Mass is a measure of the amount of matter an object contains. It is the amount of stuff a body is made of. Mass is constant everywhere. The unit of mass is kilogram (Kg). A gravitational field is the region where a mass experiences a force. The gravitational field strength on the Earth is approximately 10 N/kg CALCULATION EXAMPLES 1. What is the weight of a body of mass 20kg if the gravitational field strength is 10 N/Kg? Mass = 20k, g = 10 N/kg W eight = ? Weight = mass X gravity = 20 Kg X 10 N/Kg = 200 N 2. An object has a weight of 80 N. Calculate the mass of the body. Take gravitational strength to be 10 N/Kg Mass = ?, g = 10 N/kg W eight = 80 N Weight = mass X gravity Mass = Weight/gravity = 80 N/10 N/Kg Mass = 8 Kg 1. Calculate the weight of an object which has a mass of 2000g. [ Take g = 10 N/Kg]
