P3 1 Turning Forces Key points of P3 1 - Turning Forces. 4.0 / 5 based on 2 ratings ? PhysicsForces and MotionGCSE Created by: Samantha JordanCreated on: 26-03-10 16:52 P3 1.1 Moments The moment of a force F about a pivot is F x d, where d is the perpenidicular distance from the pivot to the line of action of the force. 1 of 8 P3 1.2 Centre Of Mass The centre of mass of an object is the point where its mass is thought to be concentrated. When a suspended object is in equilibrium, its centre of mass id directly beneath the point of suspension. The centre of mass of a symmetrical object is along the axis of symmetry. 2 of 8 P3 1.3 Moments In Balance For an object in equilibrium, the sum of the anticlockwise moments about any point = the sums of the clockwise moments about that point. 3 of 8 P3 1.4 Stability The stability of an object is increased by making its base as wide as possible and its centre of mass as low as possible. An object will tend to topple over if the line of action of its weight is outside its base. 4 of 8 P3 1.5 Circular Motion For an object moving in a circle at a constant speed, the object accelerates continuously towards the centre of the circle, the centripetal force needed increases, as the mass or the speed of the object increases as the radius of the circle decreases 5 of 8 P3 1.6 Gravitational Attraction The force of gravity between two objects is an attractive force, is bigger the greater the mass of each object is, is the smaller the greater the distance between the two objects is. 6 of 8 P3 1.7 Planetary Orbits To stay in orbit at a particular distance, a small body must move at a particular speed around the larger body. The larger an orbit is, the longer the orbiting body takes to go round the orbit. 7 of 8 P3 1.8 Satellites A satellite in a geostationary orbit has a period of 24 hours and stays at the same position directly above the Earth's equator. Geostationary orbits are usually used for communication satellites. Monitoring satellites are usually in low polar orbits. 8 of 8
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