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Chapter 12: Q. 68 (page 333)

Your engineering team has been assigned the task of measuring the properties of a new jet-engine turbine. You鈥檝e previously determined that the turbine鈥檚 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 a predetermined rotation speed, cut the power, and time how long it takes the turbine to reduce its rotation speed by 50,. Your data are given in the table. Draw an appropriate graph of the data and, from the slope of the best-fit line, determine the frictional torque.

Short Answer

Expert verified

Frictional torque = 10.7 Nm.

Step by step solution

01

Given Information

Data is given as below

02

Explanation

First re-create the table by changing the rpm to rad/sec

Now plot the graph

Find slope using any two data points

Slope=(220-157)rad/s)(25-19)s=0.121rad/s2

Angular acceleration is calculated as

蝇i2=蝇i+伪t鈬�t=蝇i2伪

It shows that, slope =-12伪

so

伪=-12(slope)

Substitute the value of slope, we get

localid="1649166916354" 伪=-12(0.121rad/s2)|伪|=4.13rad/s2

To find the torque now substitute the values in 蟿=I伪, we get

蟿=(2.6kgm2)(4.13rad/s2)=10.7Nm

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