RI 2022 Forces

Chapter 4 RAFFLES INSTITUTION 2022 YEAR 5-6 PHYSICS DEPARTMENT FORCES Content • Types of forces • Equilibrium of forces • Turning effects of forces • Centre of gravity Learning Outcomes Candidates should be able to: (a) recall and apply Hooke's law (F = kx, where k is the force constant) to new situations or to solve related problems. (b) describe the forces on mass, charge and current-carrying conductor in gravitational, electric and magnetic fields, as appropriate. · (To be covered in later topics.) (c) show qualitative understanding of normal contact forces, frictional forces and viscous forces including air resistance. (No treatment of the coefficients of friction and viscosity is required). (d) show an understanding that the weight of a body may be taken as acting at a single point known as its centre of gravity. (e) define and apply the moment of a force and the torque of a c9uple. (f) show an understanding that a couple is a pair of forces which tends to produce rotation only. (g) apply the principle of moments to new situations or to solve related problems. (h) show an understanding that, when there is no resultant force and no resultant torque, a system is in equilibrium. (i) use a vector triangle to represent forces in equilibrium. U) derive, from the definitions of pressure and density, the equation p = pgh. (Not in H1) (k) solve problems using the equation p = pgh. (Not in H1) (I) show an understanding of the origin of the force of upthrust acting on a body in a fluid. (Not in H1) (m) state that an upthrust is equal in magnitude and opposite in direction to the weight of the fluid displaced by a submerged or floating object. (Not in H1) (n) calculate the upthrust in terms of the weight of the displaced fluid. (Not in H1) (o) recall and apply the principle that, for an object floating in equilibrium, the upthrust is equal in magnitude and opposite in direction to the weight of the object to new situations or to solve related problems. (Not in H1) 1

4.1 Y(lo/, there's empty space hllrll fllf' u, to cniwl ... You silly worm, this space is for students to jot down important notes. 4.2 Weight When lab&lli ng fore&S ina Fru Body Diagram, you nud to write out 'weight", 'normal contact force " in full, insteod of just WorN . Normal contact force RAFFLES INSTITUTION 2022 YEAR 5-6 PHYSICS DEPARTMENT Introduction To date, physicists recognize four fundamental forces in nature: 1. The gravitational force 2. The electromagnetic force 3. The strong nuclear force} not in the syllabus 4. The weak (nuclear) force All other forces we know can be derived from these four fundamental forces. Other than the gravitational force, most forces such as pushes, pulls and other contact forces like the normal force and friction, can be considered due to the electromagnetic force acting at the atomic level. In the H2 Physics syllabus, you will learn that a mass experiences a gravitational fo