1. The problem statement, all variables and given/known data A mirror is moving to the right with a velocity 15 m/s, and an object is moving to the right with a speed of 5m/s. All speeds are wrt ground. Find the velocity of image wrt ground. 2. Relevant equations 3. The attempt at a solution I present to you two probable solutions: 1) Using formula: VIMAGE=2VMIRROR-VOBJECT Now, its a mere substitution problem. Using right as positive direction, we get the required velocity as 25m/s to the right. 2) This is a controversial one. I thought about this as i like to explore all the different correct of incorrect methods of a problem. the above problem is equivalent to: the mirror is moving to the right with a velocity of 10m/s and the object is at rest. Now, substituting in the formula used in the previous method, VIMAGE=20m/s to the right. Now, my book says that that the correct answer is 10m/s, but its not matching with any of my answers. Please check it and let me know why both are incorrect.