Chemical reactions happen when a. atoms attract or repel one another b. heat is created by friction c.  two or more substances are mixed substances are heated or d. cooled

What is hidden during a lunar eclipse? isn't the moon hidden?

Imagine that someone pushes one marble toward a motionless marble. would there still be action-reaction forces involved in the collision? how might the marbles’ motions be changed? ?

If an astronaut takes an object to the moon the following is true (choose only one). a the mass will change but the weight will be the same. b both the mass and the weight of the object will be the same. c the weight will change but the mass will be the same. d both the mass and the weight of the object will change.