P3 Forces (Moments, CoM, Stability) 0.0 / 5 ? PhysicsForces and MotionGCSEAQA Created by: ColdAsteroidCreated on: 04-01-16 15:51 What is a lever? Machine that helps us do work more easily (small->large force) 1 of 37 What is a pivot? A point at which something turns. 2 of 37 What is the centre of mass/gravity? The point where all weight/mass appears to act. 3 of 37 Step one of finding the CoM/G in an irregular shaped lamina. 1)Freely hang the lamina from a retort stand. 4 of 37 Step two. Hang plumb line from the same point as the retort stand. 5 of 37 Step three. Mark plumb line on lamina with x's and join together. 6 of 37 Step four. Rotate and repeat process with plumb line. Different hole 7 of 37 Step five. Where the two lines cross will be the centre of gravity/mass. 8 of 37 Step six. To check, rotate and do with a third point. 9 of 37 How do we determine whether an object will topple or not? The position of an object's centre of mass/gravity will. 10 of 37 How do we increase the stability of an object? 1)Lower the COG. 2)Increase the area of the base. 11 of 37 Give any two examples of this being used. eg/ wine glass, traffic cone -a larger base/mass at the bottom 12 of 37 How do we determine toppling from tilting? Line in base=NOT TOPPLE Line outside base=WILL TOPPLE 13 of 37 What is a moment? Any turning effect which is caused by a force. (a spanner) 14 of 37 What are the two parts of a lever? Pivot and the rod (the body of the lever) 15 of 37 What is the formula for a moment? Moment,M (Nm)=Force,F (N) x distance,d (m) 16 of 37 On a seasaw, how can a large person reduce his force applied? Sit closer to the pivot (less distance) 17 of 37 How can the seasaw be balanced if there is a large person and a small person? Small person=large distance, large person=small distance 18 of 37 How do we know if the moments are balanced on either side of the pivot? The object will not turn. 19 of 37 Give a simplified write out of the principle of moments. Total anticlockwise moments=total clockwise moments 20 of 37 What is the time period of a pendulum? Time taken-swing from 1 side to other then back to orginal point 21 of 37 What is the equation of finding the time period of a pendulum? Time period(s)=1/frequency, F 22 of 37 What are the factors of determining the time period? Length. But not the mass of it or how high it's swung from. 23 of 37 True or false. Liquids are compressible. False. Liquids are virtually incompressible. 24 of 37 Therefore, where is the pressure transmitted? In ALL DIRECTIONS 25 of 37 How do we find the pressure in a liquid? Pressure, P(Pa)=Force, F(N)/Area, A(m2) 26 of 37 What is the same for both master and slave pistons? Pressure 27 of 37 If the work done is the same for both pistons, what should happen to the distances they travel? They should move proportional to the force given and work done 28 of 37 Eg/ On the master, if there is a small force and large distance, how much should the large piston rise? A smaller amount. 29 of 37 What is velocity? Vector quantity of speed and direction 30 of 37 In circular motion, the speed is the same but the object continues to accelerate. Explain why. It is constantly changing direction. So it's accelerating 31 of 37 What is the centripetal force? A resultant force to cause the object to accelerate. (N's 1st law) 32 of 37 Where is the centripetal force always directed to? The centre of the circle 33 of 37 What provides the centripetal force on a rope/wire? Tension 34 of 37 What provides the centripetal force on a track/road? Friction 35 of 37 What provides the centripetal force for satellites in orbit? Gravitational attraction between satellite and Earth 36 of 37 How do you increase the centripetal force? Increase: mass and speed of object. Decrease: radius of object 37 of 37
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