This preview shows pages 1–3. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: Muraj, Hamza Homework 19 Due: Mar 8 2006, 4:00 am Inst: Florin 1 This printout should have 12 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. The due time is Central time. 001 (part 1 of 1) 10 points An object attached to the end of a string swings in a vertical circle of radius 2 . 4 m as shown. At an instant when = 36 , the speed of the object is 10 m / s and the tension in the string is 29 N. The acceleration of gravity is 9 . 8 m / s 2 . 1 m / s 2 9 N 2 . 4 m 36 9 . 8 m / s 2 What is the mass m of the object? Correct answer: 0 . 807656 kg. Explanation: Let : = 36 , v = 10 m / s , r = 2 . 4 m , and g = 9 . 8 m / s 2 . v T mg R g Basic Concepts: F r = ma r = mv 2 r Solution: The centripetal acceleration is a r = v 2 r . According to Newtons second law, the total force in the radial direction should be equal to F r = ma r . The forces acting on the mass are the ten sion T on the string, directed radially inward, and the weight force, whose component in the radial direction is mg sin . The radial com ponent of the resultant force is then F r = ma r = T + mg sin , or m v 2 R g sin = T . Finally, m = T v 2 R g sin = (29 N) (10 m / s) 2 (2 . 4 m) ( 9 . 8 m / s 2 ) sin(36 ) = . 807656 kg . 002 (part 1 of 1) 10 points A block of mass 2 . 88 kg is kept at rest as it compresses a horizontal massless spring ( k = 59 . 8 N / m) by 11 . 4 cm. As the block is released, it travels 0 . 537 m on a rough hori zontal surface before stopping. The acceleration of gravity is 9 . 8 m / s 2 . Calculate the coefficient of kinetic friction between surface and block. Correct answer: 0 . 0256382 . Explanation: Using the workenergy theorem, we have k x 2 2 = mg . Therefore = k x 2 2 mg = (59 . 8 N / m)[(11 . 4 cm)(0 . 01 m / cm)] 2 2(2 . 88 kg)(9 . 8 m / s 2 )(0 . 537 m) = 0 . 0256382 . 003 (part 1 of 1) 10 points Muraj, Hamza Homework 19 Due: Mar 8 2006, 4:00 am Inst: Florin 2 The two blocks are connected by a light string that passes over a frictionless pulley with a negligible mass. The 5 kg block lies on a rough horizontal surface with a constant coefficient of kinetic friction 0...
View
Full
Document
This note was uploaded on 04/12/2010 for the course PHY 58195 taught by Professor Turner during the Spring '09 term at University of Texas at Austin.
 Spring '09
 Turner

Click to edit the document details