Which characteristics is common in mature rivers river

Name three different units of energy used to measure heat and describe what type of situations each is usually used.

Where is the potential energy throughout the loading, cocking, and releasing of the trebuchet?

If two students are running down the hall toward each other, trying to get to class, and they have the same mass and acceleration, what will happen when they collide? will their forces cancel out or will each one experience a reaction?