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Resolving Vectors This links to [[Physics - Combining Vectors]]S , since it’s like doing it in reverse. What is resolving vectors?? Finding the horizontal and vertical component of a vector. What is resolving vectors opposite to…?? Combining a vector. How is the the horizontal component of $F$ written?? $F_x$. What is $F_x$?? The horizontal component of vector $F$. How is the the vertical component of $F$ written?? $F_y$. What is $F_y$?? The vertical component of vector $F$.

Combining Vectors Combining Vectors is [[Physics - Resolving Vectors]]S in reverse, or vice-versa. What is the golden rule for adding vectors?? Always add vectors tip to tail. Combine these vectors, a boat moving $10kmh^{-1}$ across a $10kmh^{-1}$ flowing river PHOTO?? PHOTO $\sqrt{10^2 + 10^2} = \sqrt{200} = 10\sqrt{2} kmh^{-1}$ When can Pythagoras be used to combine two vectors?? When two known forces are at a right angle. How can you work out the angle between two forces?

Uncertainty What are the two types of uncertainty?? Absolute uncertainty Percentage uncertainty What is absolute uncertainty?? A number that gives the range of values for an experiment. E.g. $7.3mm \pm 0.2mm$ What is percentage uncertainty equal to for a single measurement?? The resolution of the equipment. What is percentage uncertainty equal to for multiple measurements?? The range of values divided by two. What is the percentage uncertainty for $0.65mm, 0.58mm, 0.62mm$?? $\pm 0.

Forces What is the weight of an object?? The force acting vertically downwards. What is the normal reaction?? The force acting perpindicular from a surface when an object is in contact with the surface. What is the normal reaction the same as?? The weight of an object on a surface. What is the name of the force acting perpindicular from a surface on an object resting on the surface?? The normal reaction. What is friction?? The force which opposed the motion between two rough surfaces.

Models What is a model?? A model is a simplified representation of a physical situation, made by accepting assumptions. What’s an example of a common assumption?? No air resistance Constant gravity Uniform mass What two questions need to be asked when setting up a mathematical model?? What are your assumptions? What are the variables? If the answer presented by a mathematical model is unreasonable, what should be done?? You should reconsider your assumptions.

Units and Prefixes Units and Prefixes are a simple topic but very important and foundational for the rest of physics as a whole. It’s one of those things that are important learning because it improves fluency in thought involving physics problems and having a good conceptual understanding of what the units actually represent can also be helpful. Units What are the two types of units?? Base units Compound units What is a base unit?