1/3 of this Pre-Lab

2. Projectile Motion In this experiment you will learn to describe motion in two dimensions. This lab also introduces, and provides practice with, experimental uncertainty. In the pre-lab you are asked to read the section on uncertainty. PRE-LAB Experimental Uncertainty: In a simple experiment to determine the density of steel, you select a small metal sphere that you suspect of being made of steel and measure its radius and mass. Using some simple instruments, you estimate that the sphere's radius lies in the range 1.15[cm] to 1.25[cm] and its mass lies in the range 60[g] to 70[g]. The volume of a sphere is given by V = (4/3) Ity by and the density (symbol p) is given by the mass divided by the volume. 1) Given the possible range of values for the radius, what is the range of values for the volume (i.e., find the smallest and largest possible volumes)? Show your work. 2) Identify the values of mass and volume that lead to the smallest possible value for the calculated density. What is the density based on these values? 3) Identify the values of mass and volume that lead to the largest possible value for the calculated density. What is the density based on these values? When expressing the uncertainty in a measured or calculated value, one convention is to express it in the form x + Ax. The value x is just the midpoint between the minimum and maximum values and Ar is one half of the range of the minimum and maximum values. We call Ar the absolute uncertainty. Using this notation, the radius of the ball is expressed as (1.20 + 0.05) [cm]