Hello, I just started a Physics course last week and unfortunatly I am stuck with a teacher that can't teach So , I have come across a few questions that I need help in. 1. A car travelling at 90km/h strikes a tree. The front end of the car compresses and the driver comes to rest after travelling 0.80m . What was the average acceleration od th driver during the collision? 2. A stone dropped from the top of a cliff. It is seen to hit the ground below after 3.50seconds. How high is the cliff? 3. A heliocopter is ascending vertically with a speed of 5.50m/s . At a hight of 105m above the Earth, a package is dropped from a window. How much time does it take for the package to reach the ground? Thank you in advance.