P3.2 Using physics to make things work 0.0 / 5 ? PhysicsEnergyForces and MotionForcesGCSEAQA Created by: Emily_OCreated on: 02-02-14 12:08 What is the centre of mass of an object? The point at where its mass may be thought to be concentrated 1 of 18 Where is the centre of mass if an object is freely suspended? Directly below the point of suspension 2 of 18 Where is the centre of mass of a symmetrical object? Along the axis/line of symmetry 3 of 18 Equation for the time for pendulums T = 1/f (T=time period, s; f=frequency, Hz) 4 of 18 How does the length of a pendulum affect the time period? The longer the pendulum, the longer the time period 5 of 18 What is a moment? The turning affect of a force 6 of 18 Equation to caculate size of moment M=Fxd (M=moment of force,Nm; F=force,N; d=perpendicular distance from the line of action of the force to the pivot,m) 7 of 18 What should the moments be like if an object isn't turning? The total clockwise moment must be exactly balanced by the total anticlockwise moment about any pivot 8 of 18 Equation for calculating the size of the force, or its distance from the pivot, acting on an object that's balanced W1d1=W2d2 9 of 18 What happens to an object if the resultant moment about its point of turning isn't zero? It topples over 10 of 18 How can you increase the stability of an object? Make its base as wide as possible and its centre of mass as low as possible 11 of 18 What is pressure? Force divided by the area which the force acts on (P=F/A) 12 of 18 What is the unit for pressure? The pascal (Pa) which is equal to 1N/m/\2 13 of 18 What do hydraulic systems do? Use the pressure in a fluid to exert a force 14 of 18 What does the force exerted by a hydraulic system depend on? The force exerted by the system; the area of the cylinder which this force acts on; and the area of the cylinder that exerts the force 15 of 18 What happens when an object moves in a circle? (circular motion) It continuously accelerates towards the centre of the circle but this acceleration changes the direction of motion of the body, not its speed 16 of 18 What is centripetal force? The force causing the acceleration towards the centre of a circle of an object moving round the circle 17 of 18 What causes the centripetal force on an object to increase? (3) If the mass of the object increases; the speed of the object increases; or the radius of the circle decreases 18 of 18
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