# NTNUJAVA Virtual Physics LaboratoryEnjoy the fun of physics with simulations! Backup site http://enjoy.phy.ntnu.edu.tw/ntnujava/

## Easy Java Simulations (2001- ) => misc => Topic started by: Fu-Kwun Hwang on November 26, 2010, 01:23:48 pm

 Title: projection of a vector: inner product A‧B, and cross productor AXB Post by: Fu-Kwun Hwang on November 26, 2010, 01:23:48 pm The following applet shows 1. The inner product(which is a scale) is defined as $\vec{A}\cdot\vec{B}=|\vec{A}|\,|\vec{B}|\cos\theta$ ,   So projection of vector $\vec{A}$ into another direction $\vec{B}$ can be calculated as $\vec{C}=(\vec{A}\cdot \hat{B}) \hat{B}=(\vec{A}\cdot\frac{\vec{B}}{|\vec{B}|})\frac{\vec{B}}{|\vec{B}|}$ 2. The cross product $\vec{D}=\vec{A}\times\vec{B}$, $|\vec{D}|=|\vec{A}|\, |\vec{B}| \sin\theta$ where $\theta$ is the angle between $\vec{A}$ and $\vec{B}$