<font color="yellow">What? Gravity is proportional to mass, so the gravity constant is the constant of proportionality, just like -(3.14) is to a circle, and constant speed is to time, etc. </font><br /><br />Nope. Big G is a constant of proportionality, but not betweeen force and acceleration.<br /><br /><font color="yellow">The speed of light is proportional 186,000 miles per second, so the speed of light is the constant of proportionality, right? </font><br /><br />The speed of light is a constant, but not a constant of proportionality... at least, not in the context of our current conversation.<br /><br /><font color="yellow">I don't know what you want me to say. </font><br /><br />Good! If it were simple, you wouldn't learn anything...<br /><br /><font color="yellow">Whoops! Here's your question. <br /><br />Your question: Force is directly proportional to acceleration. What is the constant of proportionality? </font><br /><br />Yes. That is the correct question.<br /><br /><font color="yellow">You would pick force; the laws of motion break down as we leave our star, and in quantum. </font><br /><br />I mean in simple, ordinary conditions. No need to get fancy here. This is just ordinary Newtonian stuff.<br /><br /><font color="yellow">The constant of proportionality is force.</font><br /><br />Nope. Please stop guessing and start thinking. Perhaps go review what a constant of proportionality is. Here is the question, restated to be as simple as possible:<br /><br />What is the constant of proportionality between force and acceleration?