Effects of forces

What the syllabus asks of you

• Know that forces may produce changes in the 9 Define the spring constant as force per unit size and shape of an object extension; recall and use the equation k = F / x
• Sketch, plot and interpret load–extension 10 Define and use the term ‘limit of proportionality’ graphs for an elastic solid and describe the for a load–extension graph and identify this associated experimental procedures point on the graph (an understanding of the elastic limit is not required)
• Determine the resultant of two or more forces 11 Recall and use the equation F = ma and know acting along the same straight line that the force and the acceleration are in the same direction
• Know that an object either remains at rest or continues in a straight line at constant speed unless acted on by a resultant force
• State that a resultant force may change the 12 Describe, qualitatively, motion in a circular path velocity of an object by changing its direction of due to a force perpendicular to the motion as: motion or its speed (a) speed increases if force increases, with mass and radius constant (b) radius decreases if force increases, with mass and speed constant (c) an increased mass requires an increased force to keep speed and radius constant ( F = mv 2 / r is not required) continued Core Supplement
• Describe solid friction as the force between two surfaces that may impede motion and produce heating
• Know that friction (drag) acts on an object moving through a liquid
• Know that friction (drag) acts on an object moving through a gas (e.g. air resistance)