tracy stands on a skateboard and tosses her backpack to her friend who is standing in front of her. which best describes the acceleration tracy experiences?

For the car in the picture ,in which direction is the normal force? -into the screen -down -out of the screen -up

Which are true about beta reactions? there will be more than one answer. a. it has no change b. it doesn't change the mass of the number c. it has a mass of 0.0005 atoms d. it causes transmutation.

Is the number of complete movements of a wave per second.