An object is dropped near the earth's surface. at the end of 4.0 s, how fast is it falling in m/s? (ignore air resistance.)

For free falling bodies, the final velocity may be calculated through the equation,
                                   Vf = gt
Where g is the acceleration due to gravity (9.8 m/s²) and t is the time elapsed. Substituting the known values,
                                   Vf = (9.8 m/s²) x (4 s) = 39.2 m/s
Therefore, the object's velocity is approximately 39.2 m/s. 

The charge of an ion with 55 protons and 52 electrons is +3. the reason is because protons are positive, and there are three more than the amount of negative electrons.