Class Management I Help Homework 8 Begin Date: 3/29/2018 12:00:00 AM Due Date: 4
ID: 2038460 • Letter: C
Question
Class Management I Help Homework 8 Begin Date: 3/29/2018 12:00:00 AM Due Date: 4/9/2018 11:59:00 PM End Date: 4/9/2018 11:59:00 PM (6%) Problem 12: TV broadcast antennas are the tallest artificial structures on Earth. In 1987, a 73.5 kg physicist placed himself and 400 kg of equipment at the top of one 610-m high antenna to perform gravity experiments Randomized Variables m- 73.5 kg × By how much was the antenna compressed in mm, if we consider it to be equivalent to a steel cylinder 0.150 m in radius? The Young's modulus of steel is 2.10 x 1011 N/m2 Grade Summary Deductions Potential 0% 100% sin0 cotan0asin acos0 atan0 acotan sinhO cosh0 tanh cotanh0 cosO Submissions emaining: 5 Attempts r (090 per attempt) detailed view *123 0% 0% END Degrees Radians NO CLEAR Submit Hint I give up! Hints: 2 % deduction per hint. Hints remaining: 3 Feedback: 2% deduction per feedback.Explanation / Answer
Cross-sectional area of cylinder, radius 0.150m is: A = ?r² =?(0.150)² = 0.07069 m²
Compressive force F = mg = (73.5+400) x 9.81 = 4645 N
E = 210x10?Pa
E = FL/(eA)
e = FL/(EA)
= 4645 x 610 / (210x10? x 0.07069)
= 1.9 x 10-4 m (= 0.19mm)