Force and Motion

Finding Work Done from a Graph

Finding Work from Force-Displacement GraphIn a Force-Displacement graph, work done is equal to the area in between the graph and the horizontal axis. Example:The graph above shows the force acting on a trolley of 5 kg mass over a distance of 10 m. Find the work done by the force to move the trolley.Answer:In a Force-Displacement graph, work done … Read more

Work Done by/Against the Gravity

Work Done Against the Force of Gravity Example:Ranjit runs up a staircase of 35 steps. Each step is 15cm in height. Given that Ranjit’s mass is 45kg, find the work done by Ranjit to reach the top of the staircase. Answer:In this case, Ranjit does work to overcome the gravity. Ranjit’s mass = 45kgVertical height … Read more

Work

Work Work done by a constant force is given by the product of the force and the distance moved in the direction of the force. The unit of Nm(Newton metre) or J(Joule). Work is a scalar quantity. Formula When the direction of force and motion are same, θ = 0o, therefore cosθ = 1Work done, … Read more

Forces in Equilibrium

Vectors in Equilibrium When 3 vectors are in equilibrium, the resultant vector = 0. After joining all the vectors tail to head, the head of the last vector will join to the tail of the first vector. Forces in equilibrium Forces are in equilibrium means the resultant force in all directions are zero. When the … Read more

Inclined Plane

Inclined PlaneWeight component along the plane = Wsinθ.Weight component perpendicular to the plane = Wcosθ. Example:A block of mass 2 kg is pulling along a plane by a 20N force as shown in diagram above. Given that the fiction between block and the plane is 2N, find the magnitude of the resultant force parallel to … Read more

Vector Resolution

Vector ResolutionA vector can be resolve into 2 component which is perpendicular to each others. Example:Diagram above shows a lorry pulling a log with an iron cable. If the tension of the cable is 3000N and the friction between the log and the ground is 500N, find the horizontal force that acting on the log.Answer: … Read more

Vector Addition

Vector Addition – Triangle Method Join the tail of the 2nd vector to the head of the 1st vector. Normally the resultant vector is marked with a double arrow. Vector Addition – Parallelogram Method Join the tail of the 2nd vector to the tail of the 1st vector. Normally the resultant vector is marked with … Read more

Vector Quantities

Vector and Scalar Quantity A scalar quantity is a quantity which can be fully described by magnitude only. A vector quantity is a quantity which is fully described by both magnitude and direction. Vector Diagram The arrow shows the direction of the vector. The length representing the magnitude of the vector. Equal Vector Two vectors … Read more

Pulley

There are 2 types of pulley, the fixed pulley and the movable pulley. (“Fixed pulley” by César Rincón available under a Creative Commons Attribution-Share Alike 3.0 Unported) (“Movable pulley” by Johjak available under a Creative Commons Attribution-Share Alike 3.0 Unported) In SPM, we will only discuss the fixed pulley. The fixed pulley change the direction, without changing the magnitude of the force. In … Read more