Question

Your engineering team has been assigned the task of measuring the properties of a new jet-engine turbine. You've previously determined that the turbine's moment of inertia is 2.6 kg?m2. The next job is to measure the frictional torque of the bearings. Your plan is to run the turbine up to several different initial predetermined rotation speeds, ?i, cut the power, and time how long it takes the turbine to reduce its rotation speed by 50% in each case.

Graphing either t versus ?i or ?i versus t gives a straight line. In the graph shown, we chose to plot t on the vertical axis and ?i on the horizontal axis because Newton’s second law for rotational motion gives time as a function of angular velocity. Notice that the angular velocities were converted from rpm to rad/s (SI units) before graphing. From the equation for the line of best fit given, determine the frictional torque ?.

The picture has the data and the graph. Please explain how to find the frictional torque with as much detail as possible. Thank you!

Answer 1