Effects of Forces Cambridge CIE IGCSE Physics PDF 2021

Head to www.savemyexams.com for more awesome resources Cambridge (CIE) IGCSE Physics Your notes Effects of Forces Contents Resultant Forces Page 1 of 6...

Head to www.savemyexams.com for more awesome resources Cambridge (CIE) IGCSE Physics Your notes Effects of Forces Contents Resultant Forces Page 1 of 6 © 2015-2024 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Resultant Forces Your notes Effects of forces A force is defined as: A push or a pull that acts on an object due to the interaction with another object Forces can have a variety of effects on an object Forces can change an object's speed direction shape size Effects of forces on different objects A thrust force can cause a car to speed up, a gravitational force can cause a comet to change direction, compression forces can cause a spring to change shape The effects of forces on an object often depend on the type of force acting The push force (thrust) of an engine can cause a car to speed up, whilst the force exerted by the brakes (friction) can cause it to slow down Page 2 of 6 © 2015-2024 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources The gravitational pull of the Sun on a comet causes the comet to change direction When two opposing forces push on each end of a spring, the spring changes shape (it Your notes compresses) Resultant forces on a straight line What is a resultant force? A resultant force is a single force that describes all of the forces operating on a body When multiple forces act on one object, the forces can be combined to produce one net force that describes the combined action of all of the forces This single resultant force determines: The direction in which the object will move as a result of all of the forces The magnitude of the net force experienced by the object Balanced and unbalanced forces The forces acting on an object can be described as balanced or unbalanced Forces are balanced if multiple forces act in opposing directions with an equal magnitude in each direction The effects of the forces then cancel out There is no resultant force in that plane of direction Forces are unbalanced if the effects of the forces acting in each plane do not cancel out There is a resultant force in one or more planes of direction A book is a rest on a table The gravitational pull of the Earth on the book (weight) acts in a downward direction The push force of the table on the book (normal contact force) acts in the upward direction The forces are equal in magnitude and opposite in direction The forces are therefore balanced There is no resultant force acting on the book Zero resultant force on a book resting on a table Page 3 of 6 © 2015-2024 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Your notes A book resting on a table is an example of balanced forces Calculating resultant force Force is a vector quantity, it has both magnitude and direction When adding forces together, it is important to assign positive and negative values to show the direction in which the forces are acting If a 5 N force acts to the right and a 5 N force acts to the left on an object, then we assign one of the values as positive and one as negative So the resultant force acting on the object is resultant force = 5 + (−5) resulotant force = 0 N The forces acting on the object are equal in magnitude and opposite in direction; therefore they cancel one another out This is like two people pushing a box with equal force from opposite sides, the box doesn't move If two people push the box from the same side in the same direction, one with a 3 N force and one with a 7 N force, then the forces will add together and the box will move in the direction of the resultant force Page 4 of 6 © 2015-2024 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources resultant force = 3 + 7 resultant force = 10 N Your notes If two people push the box in opposite directions, one with a 7 N force to the left (negative) and one with a 3 N force to the right (positive), then the forces will add together and the box will move in the direction of the resultant force resultant force = (−7) + 3 resultant force = − 4 N Zero and non-zero resultant forces Zero and non-zero resultant forces acting on three objects WORKED EXAMPLE Calculate the magnitude and direction of the resultant force in the diagram below. Answer: Step 1: Assign a direction to the forces Forces acting to the right are positive Page 5 of 6 © 2015-2024 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers  Head to www.savemyexams.com for more awesome resources Forces acting to the left are negative Step 2: Add together all the forces acting on the object Your notes resultant force = (−14) + 4 + 8 resultant force = ( 14) + 12 resultant force = − 2 N Step 3: State the magnitude and direction of the resultant force The resultant force is 2 N to the left EXAM TIP Mathematically, it doesn't matter which direction you assign to be positive or negative, as long as you are consistent throughout your calculation. Page 6 of 6 © 2015-2024 Save My Exams, Ltd. · Revision Notes, Topic Questions, Past Papers