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Maths Y13 Mech
Maths Spring Y13
| Question | Answer |
|---|---|
| When integrating | Keep adding the +c and then removing it with proof at every stage e.g. v = something at t = 0 |
| v^2 = u^2 + 2as | Dont need in vector form - too complex to square vectors for single maths. Use the basic formulas and use i and j for simple algebra |
| Speed | Give magnitude |
| When integrating i and j coefficients | Make sure to add c1, c2, etc to both i and j at every stage, proving each of them into constants at each stage as per normal |
| r = xi + yj. What is r? | Position vector. Not the same thing as displacement. When calculating using suvat, add the displacement to the start point to get r. |
| Cartesian equations | Where r = xi + yj, where x and y are expressions in terms of t, can sometimes eliminate variable t to get a cartesian equation. 1. Find x and y equations 2. Rearrange easiest for t 3. Sub into the other equation 4. Simplify |
| Domain of x using cartesian | t can only be positive so shows what domain of x. e.g. x = t + 2, so x =< 2 |
| e.g. Find cartesian equation for path of particle r = (t^2 - 2)i + (t+1)j | x = t^2 - 2 y = t + 1 t = y - 1 x = (y-1)^2 - 2 x = y^2 - 2y - 1 |
| Range from projectile motion | The x displacement |
| Symmetry of projectile motion | Dont assume symmetry for e.g. landing angle. DRAW DIAGRAM. If starting at a weird point, add the vector position of its start point to the displacement |
| Phrasing for angle | '30 degrees above/below horizontal' |
| For v^2 suvat equation | No t, so is +- as multiple possible points can be there. Watch out for the +- |
| For force diagram questions | Give values if at all possible Add resistance, tension, etc if relevant - dont miss one Add acceleration value too if given |
| Resultant forces | Make sure they're *end-to-end* - rearrange if needed |
| When resolving perpendicular/parallel to slope | Make sure to add the perpendicular and parallel components of weight or other horizontal/vertical forces to the ones already in correct directions. Also make sure arrows going correct way to be end-to-end of resultant of weight |
| When given the bearing something is moving at and multiple times in your answer | To remove solutions, check to make sure that at both times it's moving in the correct bearing not the opposite direction. |