What is the concentration of a solution when 50 mL of ethanol is diluted to 140 mL with water?

Aproton is projected toward a fixed nucleus of charge +ze with velocity vo. initially the two particles are very far apart. when the proton is a distance r from the nucleus its velocity has decreased to 1/2vo. how far from the nucleus will the proton be when its velocity has dropped to 1/4vo?

Aforce of 240.0 n causes an object to accelerate at 3.2 m/s2. what is the mass of the object?

What is the stall speed at sea level of an airplane that weights 10000 lbs., has a wing area of 300ft^2, and a maximum lift coefficient of 1.4? what is the stall speed if flaps that double cl,max are applied?