# HSC Physics Formulae Sheet

/Here are some notes to assist students in using the new HSC Physics Formulae Sheet that will be used in HSC examinations from 2019. These notes will be updated during 2018 and 2019 as the topics are taught in schools.

- The weight (F) of an object is given by F=mg, where m is mass and g is acceleration due to gravity.
- The force of static friction (F) between two surfaces is given by F
_{}≤μ_{s}N, where μ_{s}is the coefficient of static friction and N is the normal reaction force between the two surfaces. - Linear momentum (
**p**) is given by**p**= m**v**, where m is mass and**v**is velocity. - Linear momentum is conserved in all collisions or explosions. This means that for a system of two masses
- Kinetic energy is only conserved in elastic collisions. This means that for a system of two masses
- The Doppler effect equation for sound waves is , where
*f*^{'}is the frequency measured by the observer,*f*is the frequency of the sound waves emitted by the source,*v*is the speed of sound and*v*_{o}and*v*_{s}are the velocities of the observer and source respectively. Note: Draw the arrow from the observer to the source. This is the positive direction for choosing the signs of the velocity vectors,*v*_{o}and*v*_{s} - The heat conduction equation is where the negative sign indicates that the heat flow ∆
*Q*is from the high temperature end to the lower temperature end and the change in temperature ∆*T*is the final temperature minus the initial temperature. The thermal conductivity of the material is*k*, the cross sectional area that the heat flows through in a time ∆*t*is*A*and ∆*x*is the distance between the end points.