RI 2025 summaries all chapters

H2 Physics 2025 Revision 1 Chapter 1: Measurement 1. S.I. Units • The seven base units are: metre (m), kilogram (kg), second (s), ampere (A), kelvin (K), mole (mol) and candela (cd). • Derived units are defined in terms of base units. They are expressed as products or quotients of base units. • An equation is said to be homogeneous or dimensionally consistent if every term on both sides of the equation has the same base units. • A homogeneous equation may not be true or correct. 2. Errors and Uncertainties Item Accuracy Precision Instrument Calibration of instrument Smallest division of instrument Measurements Closeness of average to true value Closeness of measurements to one another • Systematic errors result in all readings or measurements being always smaller or always larger than the true value by a fixed amount. • Random errors result in readings or measurements being scattered about the true value. • Accuracy is the degree of closeness of the average value of the measurements to the true value. It is affected by systematic error. • Precision is the degree of agreement between repeated measurements of the same quantity. It is affected by random error. • Calculations: If Q = a X ± b Y, then ∆Q = |a| ∆X + |b| ∆Y. If mnQ aX Y= × or m n XQa Y= , then Q XYmnQ XY ∆ ∆∆= + . Percentage uncertainty of Q = 100%Q Q ∆ × .  A bsolute uncertainty Q∆ should always be expressed to 1 s.f.  Q uantity Q should be expressed up to the same decimal place as Q∆ . Eg: ( ) 19.81 0.02 m sgg −±∆ = ±  Fractional and percentage uncertainty is expressed to 2 s.f. Eg: 0.02 0.0020 (2 s.f.) 0.20 % (2 s.f.)9.81 g g ∆ = = = 3. Scalars & Vectors • A scalar quantity has a magnitude only. • A vector quantity has both a magnitude and a direction.

H2 Physics 2025 Revision 2 Chapter 2: Kinematics 1. Interpretation of Graphs s – t graph v – t graph a – t graph Gradient instantaneous velocity ds vdt= = = Gradient instantaneous acceleration dv adt= = = Area under the graph 2 1 change in displacement t t v dt s= = ∆ = ∫ Area under the graph 2 1 change in velocity t t a dt v= = ∆ = ∫ 2. Rectilinear Motion (1-D) ( )gradient vua t −= = v u at∴= + (1) ( )1area 2s u vt= = + (2) substituting (1) into (2), 21 2s ut at= + (3) and 22 2v u as= + (4) Equations (1) to (4) apply only to motion in a straight line at constant acceleration. 3. Solving kinematics problems • Draw diagram(s) and transfer data from the question onto the diagram(s). • Indicate positive displacements along the vertical and horizontal directions. • Ensure that sign conventions are applied consistently to all quantities. • Apply the above equations independently along the vertical and horizontal directions. t / s s / m t1 0 t / s v / m s −1 t1 0 t2 a / m s −2 t / s t1 0 t2 velocity v t time u 0

H2 Physics 2025 Revision 3 4. Projectile Motion