Gravity

• gravity is a non-contact force
• gravity is the force responsible for the formation of galaxies, stars and planets
• weight is the force acting on an object due to gravity
• the wight of an object depends on the gravitational field strength at the point where the object is
• weight (N) = Mass (Kg) X Gravitational field strength (N/Kg)
• W = m g
• you can use a newton meter to find the newtons
• weight and mass are directly proportional
• the weight of an object may be considered to act at a single point referred to as the objects ’centre of mass’ n
• the centre of mass of an irregular shaped 2-d object can be found by used a pin, some string and a small mass. by pinning the 2-d object up on a board with the string hanging from the pin the string will go through the centre of mass- mark with a line. rotate the object and rehang it. draw a line to show where the string hangs. where the lines cross is the centre of mass of the shape.