WJEC Physics for AS Level: Revision Workbook

Q19 Dominic completes a table of vector and scalar values: Vectors Scalars Force Temperature Work Displacement Velocity Energy (a) State which of Dominic’s choices are incorrect. [2] ............................................................................................................................................................................................................................................................................................................................ ............................................................................................................................................................................................................................................................................................................................ ............................................................................................................................................................................................................................................................................................................................ (b) In fluid dynamics, the viscosity ( Ɋ ) of a fluid can be given by the equation: k uL ρ = where k is a dimensionless number, ɏ the density of the fluid, u the speed of the flow and L is a characteristic length. (c) (i) Explain why N s m −2 is a valid unit for the viscosity, Ɋ . [4] ............................................................................................................................................................................................................................................................................................................................ ............................................................................................................................................................................................................................................................................................................................ ............................................................................................................................................................................................................................................................................................................................ ............................................................................................................................................................................................................................................................................................................................ ............................................................................................................................................................................................................................................................................................................................ (ii) The dimensionless number, k, in the equation is an important factor in determining the motion of a cricket ball. Calculate k for a cricket ball with characteristic length ( L ) of 7.1 cm, travelling through air of density 1.16 kg m −3 and viscosity 1.87 × 10 −5 N s m −2 at a speed of 41.2 m s −1 . [3] ............................................................................................................................................................................................................................................................................................................................ ............................................................................................................................................................................................................................................................................................................................ ............................................................................................................................................................................................................................................................................................................................ ............................................................................................................................................................................................................................................................................................................................ ............................................................................................................................................................................................................................................................................................................................ Section 1 Basic physics | 19 Unit 1 Practice questions