This preview shows pages 1–2. 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: Physics 140  Discussion 06  Solutions 5.3. I DENTIFY : Both objects are at rest and 0. a = Apply Newtons first law to the appropriate object. The maximum tension max T is at the top of the chain and the minimum tension is at the bottom of the chain. S ET U P : Let y + be upward. For the maximum tension take the object to be the chain plus the ball. For the minimum tension take the object to be the ball. For the tension T threefourths of the way up from the bottom of the chain, take the chain below this point plus the ball to be the object. The freebody diagrams in each of these three cases are sketched in Figures 5.3a, 5.3b and 5.3c. b c 75 0 kg 26 0 kg 101 0 kg. m + = . + . = . b 75 0 kg. = . m m is the mass of threefourths of the chain: 3 4 (26 0 kg) 19 5 kg. m = . = . E XECUTE : (a) From Figure 5.3a, = y F gives max b c T m g + = and 2 max (101 0 kg)(9 80 m/s ) 990 N. T = . . = From Figure 5.3b, = y F gives min b T m g = and 2 min (75 0 kg)(9 80 m/s ) 735 N. T = . . = (b) From Figure 5.3c, = y F gives b ( ) + = T m m g and 2 (19 5 kg 75 0 kg)(9 80 m/s ) 926 N. T = . + . . = E VALUATE : The tension in the chain increases linearly from the bottom to the top of the chain. Figure 5.3ac __________________________________________________________________________________ 5.20. I DENTIFY : Apply m = F a r r to the composite object of elevator plus student tot ( 850 kg) = m and also to the student ( 550 N). w = The elevator and the student have the same acceleration. S ET U P : Let y + be upward. The freebody diagrams for the composite object and for the student are given in Figures 5.20a and b. T is the tension in the cable and n is the scale reading, the normal force the scale exerts on the student. The mass of the student is 56 1 kg. m w/g = = . E XECUTE : (a) y y F ma = applied to the student gives ....
View
Full
Document
This note was uploaded on 02/15/2012 for the course PHYS 140 taught by Professor Uher during the Winter '10 term at University of Michigan.
 Winter '10
 Uher
 Physics

Click to edit the document details