Everyday experience tells that a given ‘force produces different magnitudes of acceleration for different bodies. Put a baseball and a bowling ball on the floor and give both the same sharp kick. Even if don’t actually do this, you know the result.The baseball receives a noticeably larger acceleration than the bowling ball. The two accelerations differ because the mass of the baseball differs from the mass of the bowling ball but what, exactly, is mass?
We next apply that same force (we would need some way of being certain it is the same force) to a second body, whose mass is not known. Suppose we find that this body X accelerates. We know that a less massive baseball receives a greater acceleration than a more massive bowling ball when the same . force (kick) is applied to both.
Our conjecture will be useful, of course, only if it continues to hold when we
change the applied force to other values. For example, if we apply an 8.0 N force to the standard body, we obtain an acceleration. When the 8.0 force is applied to body X, we obtain an acceleration. Our conjecture then gives us
consistent with our first experiment. Many experiments yielding similar results indicate that our conjecture provides a consistent and reliable means 01 assigning a mass to any given body.
Since the word mass is used in everyday English, we should have some intuitive understanding of it, maybe something that we can physically sense. Is it a body’s size, weight.The answer is no, although those characteristics are sometimes confused with mass. We can say only that the mass of a body is the characteristic that relates a force on the body to the resulting acceleration. Mass has no more familiar definition; you can have a physical sensation of mass only when you attempt to accelerate a body, as in the kicking of 11 baseball or a bowling ball.