I have three physics questions.
1) if I have a velocity time graph, and the acceleration is not constant how can I calculate the displacement when the velocity is
2) A ball is dropped and let fall for 6 seconds until it crashes through a glass plate. In this crash it loses two thirds of its velocity. After the crash it takes the ball 2 s to reach the ground. How high from the ground is the glass plate?
3) How can I calculate the amount of days it takes for water with Radon with activity of 10 000 Bq/l to 1000 Bq/l, if the half-life of Radon is 3.8 days?
I feel hopeless. I don't know how to do these and the physics test is tomorrow. If someone could help me I would be really grateful.