QUIZ 3

# READ ALL CHECKPOINTS IN THE CHAPTER !
# STUDY THE NUMBERED OR UNNUMBERED FIGURES, GRAPHS, AND TABLES.
# IT DOES NOT HURT TO DO EXTRA END-OF-CHAPTER REVIEW QUESTIONS, PLUG AND CHUGS, RANKINGS , OR EXERCISES AND PROBLEMS.
#IF TIME PERMITS GET MORE PRACTICE WITH THE OUT OF SEQUENCE SAMPLE MULTIPLE CHOICE QUIZZES AT VERTICAL LEFT HAND COLUMN Q1, Q2, Q3, LINKS ETC HERE~ http://www.nvaphysics.com/P11AU11.htm .

Quiz 4 (These problems will contribute to real quiz 3 next Tuesday) Physics 11 Autumn 2011 --- Selected topics + exercises/problems from Ch. 4

Quiz 4 Physics 11 Autumn 2011 --- Selected topics from Ch. 4

REVIEW QUESTIONS~ 3, 5, 6, 10, 11, 13, 14, 15, 16, 21, 23, 28, 30, 31

PLUG AND CHUG---5, 8

RANKING--1,2, 3, 4

EXERCISES--1, 2, 7, 8, 23, 42, 43, 44, 49, 51, 53, 54

PROBLEMS--5, 6

DISCUSSIONS

REVIEW QUESTIONS

3. HINT: THE NET FORCE IN THE HORIZONTAL DIRECTION IS ZERO. What is the relationship between the magnitudes of the static friction force and the push force?

5. Once the crate slides at constant horizontal velocity, what is the relationship between the magnitudes of the kinetic friction force and the push force?

6. We reviewed this in class; generally you must overcome more friction force to get an object to move from rest (static condition) than to keep it moving ( in the kinetic condition) once it starts.

10. The larger the mass, the larger the inertia.

11. Mass does not equal weight. Mass is a measure of inertia, which resists a change in state of motion. Weight is the downward force of gravity on the object. The more mass , the more weight, but weight is not mass. On Earth , what number do you multiply times the mass to get the weight ?

13. Shake something back and forth and you are measuring its "sluggishness." What property of an object is related to its "sluggishness" ? ON the other hand, IF YOU LIFT AN OBJECT AGAINST GRAVITY YOU MUST OPPOSE WHAT FORCE?

14. MASS IS MEASURED IN WHAT UNIT? FORCE ( AND THUS WEIGHT) IS MEASURED IN WHAT UNIT?

15. WEIGHT = force of gravity. Does the weight of the hamburger change during cooking?

16. | weight | = | mass*acceleration of gravity |

21. See textbook and or lecture notes

23. Assume the brick slides horizontally without loss of generality. Hint: Force = mass*acceleration .

28. , 30., AND 31. SEE LECTURE NOTES/DISCUSSIONS IN CLASS

PLUG AND CHUG

5. |Weight | = mg

8. Net Force = mass*acceleration. NO FRICTION

RANKING

1. LET RIGHTWARD BE POSITIVE. WE SEE ALL THE NET FORCES POINT RIGHT WARD IN POSITIVE DIRECTION.
Subtract the magnitudes to get the magnitude of the net force in each case, then divide by the mass in each case to get each acceleration .

2. See class notes; In A, B, we have static friction and static equilibrium and the net force in the horizontal direction is ZERO. In C , we have kinetic friction and dynamic equilibrium (motion with constant velocity) where the LEFTWARD kinetic friction force must have the same magnitude as the force pointing to the right since the net force in the horizontal direction is also ZERO.

3. Mass does not change but weight depends on the planet; generally the larger the planet the greater the weight,

4. See figure 4.15,

EXERCISES DISCUSSIONS---CHECK BACK LATER.

PROBLEMS

5. Assume the airplane moves along the x-axis. F_x = m*a_x, where F_x is the horizontal component of force and a_x is the horizontal component of acceleration . Note: m is the mass. We have F_x = 600,00 (N) and m = 30,000 kg. Find a_x . THIS USES NEWTON'S SECOND LAW.

6. Assume LEROY moves along the x-axis. F_x = m*a_x, where F_x is the horizontal component of force and a_x is the horizontal component of acceleration . Note: m is the mass. We need to find F_x . NOTE: m = 100 kg and a_x is given from the information: a_x = change in velocity/ change in time. The change in velocity is 0 - 9.0 m/s = - 9.0 m/s and the change in time is 0.2 seconds. Thus a_x = -9.0 m/s/0.2 s = -45 m/s². We see the acceleration is negative since Leroy is slowing down in the positive direction. Now find F_x. THIS USES NEWTON'S SECOND LAW.