exam1-F01-ans - or Pcos18-T-Wcos53=ma #3 girl Scale...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Solutions for Exam #1 Fall 2001 Multiple Choice: 4 points each. 1. A 2. D 3. E 4. A 5. C 6. E 7. C 8. B Part B #1 #2 #3 #4 Time Position Time Velocity 0 0 Time Velocity Time Acc. 0 0 Time Velocity Time Acc. Time Net F 0 0 0
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Because the force from the hang mass (the tension) is much larger than the frictional force. It is basically the ONLY force in the horizontal direction. Weight and normal force cancel out in the y direction and therefore the applied force is the net force. Part C #1 A) The weight of the block and the normal force from the scale B) The weight of the scale, the (normal) force from the block and the normal force from the table C) D) E) The force from the scale on the block and force from the block on the scale are (the only) Newton’s third law force pair. #2 A) N-Wcos37=0 or N-Wsin 53=0 and T-Wsin 37=ma or T-Wcos53=ma B) N-Wcos37+Psin18=0 or N-Wsin53+Psin18=0 And Pcos18-T-Wsin37=ma
Background image of page 2
Background image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: or Pcos18-T-Wcos53=ma #3 girl Scale Assuming the girl accelerates downward and using the standard choice of coordinate system, this gives: T-W g = m g (-a) and T+N-W bl = m bl (a) If the scale is to read zero, the normal force must be zero. So we have T-W g = m g (-a) and T-W bl = m bl (a) If the block is to remain in contact with the scale, a for the block is zero. So we have T-W g = m g (-a) and T-W bl = 0 or T=W bl Combining these two gives: W bl-W g = m g (-a) or M bl (g) m g (g) = m g (-a) or g ( M bl- m g )/m g =-a So g (75-50)/(50) = -a -a = 0.5 g so a = -0.5 g The minus sign means that I chose the wrong direction for the acceleration in my initial assumption, so N S on Bl W Bl N T on S W S F Bl on S (N Bl on S ) T W g N S on B W Bl T a is 0.5 g UPWARD....
View Full Document

Page1 / 3

exam1-F01-ans - or Pcos18-T-Wcos53=ma #3 girl Scale...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online