Identify the situations that have an unbalanced force. Check all that apply. 1. A weight speeds up as it falls through the air

2. A garbage can is at rest on the ground

3. A hockey puck moves in a straight line at a constant speed

4. A bumper hit by another car moves off at an angle

5. A balloon flies across the room when the air is released

If two parallel light rays hit a mirror, they will not be parallel to each other after they reflect.

Uranium has two naturally occurring isotopes. 238u has a natural abundance of 99.3% and 235u has an abundance of 0.7%. it is the rarer 235u that is needed for nuclear reactors. the isotopes are separated by forming uranium hexafluoride uf6, which is a gas, then allowing it to diffuse through a series of porous membranes. 235uf6 has a slightly larger rms speed than 238uf6 and diffuses slightly faster. many repetitions of this procedure gradually separate the two isotopes. what is the ratio of the rms speed of 235uf6 to that of 238uf6? express your answer to five significant figures.

Ascientist wants to test ways to reduce pollution in lake . what is the bestway of doing this