# Q7 - What is the torque due to gravity around the bottom of...

This preview shows pages 1–2. Sign up to view the full content.

Physics 7B Quiz 7 Grade: DL Section: Name: _______________________ ID: _______________________ I certify by my signature that I will abide by the code of academic conduct of the University of California. Signature No books or notes. Calculators OK. Show all your work below. Answers alone do not receive credit! 1. (1.5 pts) A wrench of length 50 cm is used to tighten a large bolt. If the desired tightness of the bolt, in terms of torque, is 40 N-m, what force must be applied to the end of the wrench? Explain briefly, then do the calculation. 2. (1.5 pts) You start pedaling your bike from rest by putting downward pressure on the right-hand pedal with your right foot. In which direction is the torque around the center of the bike crank? 3. (1.5 pts) A 30-kg ladder leans up against a wall, not moving. It is 3 meters long and makes an angle of 60 degrees with the horizontal.

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

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: What is the torque due to gravity around the bottom of the ladder? (Hint: you can assume gravity acts at the center of the ladder.) torque = (length of lever arm) x (perpendicular component of force to lever) 2 Quiz 7 - Rubric Problem 1 Q - 1.5 - correct answer (80 N) reasoning: F ⊥ = τ /r = (40 N-m)/(0.5 m) R - 1.2 - minor calculational error U - 0.2 - major error Problem 2 Q - 1.5 - correct answer (to the left of the bike) and explanation (right hand rule) R - 1.0 - correct answer but wrong explanation S - 0.2 - incorrect Z - 0.0 - blank Problem 3 Lever arm = 1.5 m; perpendicular force = 150 N ∴ torque = 225 N Q - 1.5 - correct answer S - 1.0 - incorrectly obtained perpendicular component of force T - 1.0 - wrong lever arm (should be 1.5 m) U - 0.5 - major errors (both S and T or other) W- 0.0 - blank or negligible work mg cos 60 o = 150 N...
View Full Document

{[ snackBarMessage ]}

### Page1 / 2

Q7 - What is the torque due to gravity around the bottom of...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online