Sem 1 Final Review problems

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					                       LAHS Physics – Semester 1 Final Review Information

Your Semester 1 Physics Final has two parts as follows:
      Part I - Multiple Choice Questions - (Individually, 50 minutes)
      Part II - Free Response Questions - (Assigned pairs announced 1st Mon of Dec, 50 minutes)

Your Semester grade will be calculated as follows:
                             Quarter 1 percentage = 40% of grade
                             Quarter 2 percentage = 40% of grade
                          Semester 1 Final – Part I = 10% of grade
                         Semester 1 Final – Part II = 10% of grade

It is highly recommend that you study/review in small groups well ahead of your scheduled Final,
preferably with your assigned partner so that you can work out collaboration and cooperation details
ahead of time. Arrange for tutoring help with your teacher or tutors at the Tutorial Center. If you
happen to miss any part of the Final for any reason, expect to do the make-up exam(s) ALONE.

Part I - Multiple Choice Questions
The first 50 minutes of your written final on your scheduled 100-minute period will be a Multiple
Choice section. You will do this part by yourself. The questions are conceptual and quick
mathematical problems with the purpose of assessing how well you understand the concepts
discussed throughout the semester. It is a scantron exam with no partial credit for wrong answers. If
you don't know the answer, you are encouraged to guess. There is no penalty for guessing unlike
some other types of exams.

Part II - Free Response Questions
The purpose of the Free Response Section of the Final is to assess your ability to solve problems.
You will do this part with your assigned partner. This packet includes a set of review problems for you
to study. On the Monday of Finals Week, 6 of these review problems will be announced as problems
for you to prepare at home a perfect solution for grading. Then at the beginning of the last 50 minutes
of the Final, you will be asked to submit only one of the 6 perfect solutions. This problem will be
randomly chosen for each period and could be different for every Physics class. This one problem
counts as one of the Free Response solutions to be graded.

For the in class portion of the Free Response part of the Final, you will be asked to write your perfect
solution to one of the remaining review problems in this packet not previously announced on the
Monday of Finals Week. The numbers given in the problem will be changed slightly for the real test,
but the wording and pictures (if any) will not be changed. In short, you will have seen all the free
response problems on the test prior to taking the test if you study what is recommended. You will be
assigned to a partner ahead of time and if you choose to do so, you may collaborate and cooperate to
write your perfect solution during the Final. Each person in the pair will be required to turn-in their own
solutions to the single problem. You will be given a clean equation sheet to use during the exam so
that everyone has equal resources.

Generally, points for each free response problem will be awarded for the following:
           Clear diagram or free body diagram with all given data indicated
           Writing the correct equation(s) to be used in solution
           Correct mathematical manipulations and algebraic substitutions
           A clearly boxed correct answer with correct units
           A complete sentence explaining your resultant numerical answer
                            LAHS PHYSICS
                      SEMESTER 1 FINAL EQUATIONS

       sin ø = opp/hyp         cos ø = adj/hyp                tan ø = opp/adj               a 2 + b 2 = c2



                      x                   v
                v                   a            v  v o  at            x  x o  v o t  2 at 2
                                                                                             1
                      t                   t
                x  x o  vt  2 at 2         v 2  v o  2a(x  x o )          x  x o  2 (v o  v)t
                               1                        2                                 1



                                              a = -g        g = 9.8 m/s2

             x  x o  v ox t  (v o cos  o )t                          y  y o  (v o sin  o )t  2 gt 2
                                                                                                     1


               v y  (v o sin  o ) 2  2g(y  y o )                               v y  v o sin   gt
                  2




                                                    
                              F = ma             W = mg        fs   sN      fk  kN

                                        2r                   v2              mv 2
                                  v=                   ac                Fc =
                                         t                     r                r
                                              m1 m2                             Nm2
                                     F=G                    G  6.67x10 11
                                               r2                               kg2


  Moon mass = 7.35x1022 kg               Earth mass = 5.98x1024 kg                        Sun mass = 1.99x1030 kg
                       
Moon radius = 1.74x106 m             Equatorial Earth radius = 6.37x106 m                       Sun radius = 6.95x108 m
                  Distance from center of Sun to center of Earth = 1.5x1011 m
                 Distance from center of Moon to center of Earth = 3.85x10 8 m


                                                                                                       W
              W = Fdcos              W  KE
                                       net                   K = 2 mv2
                                                                 1
                                                                             PE  mgh            P
                                                                                                       t



      
                       Semester 1 Final Review Problems
Kinematics
   1. Police detectives, examining the scene of a reckless driving incident, measure the skid marks
      of a car, which came to a stop just before colliding into a Wal-Mart to be 50 meters. It is
      known that the coefficient of kinetic friction k = 0.89 between the specific brand of rubber tires
      on the car and the road. The speed limit in the area is 20 m/s (about 45 mph). Assume the skid
      marks are straight and use Newton’s laws and 1-D kinematics to determine if the driver of the
      skidding car was speeding before she began skidding?

   2. A medical relief airplane climbs to an altitude of 200 m and flies at a constant cruising velocity
      of 80 m/s. The copilot steps to the back of the plane and opens the cargo door. She wants to
      drop a medical supply package to a landing site at a remote village.
          a. Neglecting air resistance, use 2-D kinematics to determine how far (horizontally) before
             the plane flies over the village must the package be dropped?
          b. To prevent the 15 kg supply package from getting damaged, the villagers set up an
             airbag at the landing site. The airbag is capable of stopping the supply package in 0.4 s
             and stands 5 meters above the ground. Use kinematics to determine the velocity of the
             package just before it hits the airbag.




                          200 m




                                                                         Airbag

                                                 Range

   3. A skydiver jumps out of a helicopter hovering at 2500 m above the ground. She free falls for 15
      seconds before opening her parachute. Assume the parachute opens instantly and allows her
      to travel at a constant velocity of 12 m/s downwards until she reaches the ground.
          a. How much distance does she cover during the initial free fall?
          b. How much time does it take her to reach the ground?
          c. At the same time she jumps from the helicopter, her shoe comes off. How much time
             does it take her free falling shoe to hit the ground assuming no air friction?
          d. What would the final velocity of the shoe be just before it hits the ground?

   4. Consider a projectile with an initial velocity vector of 34 m/s @ 25o above the +x-axis. The
      projectile is shot from ground level on a planet different than Earth where the acceleration of
      gravity isn’t known. The Range of this projectile is 180 m and it comes to rest at the same level
      at which it was shot: yo = yf = 0 meters. Use kinematics to solve the following:
          a. Calculate the hang-time of the projectile.
          b. Calculate the acceleration of gravity on this planet.
          c. If the planet's radius was the same as the Earth's, what does the result in part B imply
             about the mass of the planet?
   5. An archer shoots an arrow from the top of a building at a speed of 28 m/s. The building is 40
      meters tall. Ignoring air resistance, find the speed with which the arrow strikes the ground
      when the arrow is fired (a) horizontally (b) vertically straight up, and (c) vertically straight down.
      You must use kinematics and the quadratic formula to solve this problem.

   6. An LAHS quarterback just about at the sideline and is 20 meters (or about 22 yards) from the
      goal line pylon (orange marker at the goal line) that is in front of him. He throws the line drive
      ball with a velocity of 24 m/s at an initial angle of 10 above the horizontal. His receiver runs at
      a constant speed 6 m/s following the goal line starting 6 meters (about 6.6 yards) away from
      the pylon at the same time the quarterback releases the ball toward the pylon. Assuming no-
      one interferes with the play, the receiver is essentially a point mass and if caught, the ball is
      caught at the same height that quarterback throws the ball, determine if the receiver reaches
      ball in time to catch it at the pylon.

Newton’s Laws Problems
  7. Consider a 65 kg clown with an initial velocity of 10.0 m/s sliding up a rough circus slide
     inclined 38 above the horizontal and measuring 16.5 m along the diagonal. The coefficient of
     friction between the slide and the clown is k = 0.25. Use Newton’s laws of motion to predict
     the highest point the clown will slide to.

                           vo
                                       k      h
                                
   8. A kinetic artist wants to build a life size double mass system in equilibrium, on an incline plane.
      The initial design consists of m1 = 35.0 kg connected to m2 = 17.5 kg by a thin, cable wrapped
      over a pulley. The artist hires you to predict the exact angle at which the system will maintain
      static equilibrium without any help from friction. Use Newton’s laws to correctly calculate the
      angle that maintains static equilibrium and get paid $750.




                                                        m2
                          m1
                                

   9. Earlier this morning I saw Ms. Satterwhite, massing in at a liberal 82 kg, skate boarding
      through the quad. Suddenly, she flipped his board upside-down and skidded the wooden board
      scraping along the concrete for 4.2 m then stopped. If the coefficient of kinetic friction between
      the skateboard and the concrete quad is 0.73, use Newton’s laws to predict the skidding
      skateboard’s initial velocity just before it began to skid.

   10. A physics student is wants to be “stuck” to the interior wall of an amusement
       park ride called the ROTOR. If the radius of the rotating cylinder is 4.2 m
       and the coefficient of static friction between the student and the rotor’s inner           R
       wall is 0.56, predict the minimum safe speed at which the Rotor’s floor can
       be removed without the student sliding down the wall.
   11. A model airplane is tied to a string and                           15
       propelled by a small electric motor in a perfect
       horizontal circle with a circumference of 23 m
       at constant speed. The plane isn’t really flying.
       Predict the time it takes for the plane to                               r
       complete one complete revolution.


   12. Consider a circus clown weighing 720 N. The coefficient of static
       friction between the clown’s feet and the ground is 0.48. She pulls
       vertically downward on a rope that passes around three frictionless
       pulleys and then tied around her feet. What is the minimum pulling
       force that the clown must exert to yank her feet out from under
       herself?




Gravity and Energy Problems
   13. Assuming you are at the equator and your mass is 68 Kg, will you weigh more when the moon
       is on your side of the earth or when the moon is on the far side of the earth? How much more
       (in Newtons)? (Assume the moon, earth and you are in a straight line in each case.)
              G = 6.673 x 10-11 Nm2/kg2
              Equatorial radius of earth = 6.38 x 106 m
              Mean radius of moon = 1.74 x 106 m
              Mass of earth = 5.98 x 1024 kg
              Mass of moon = 7.35 x 1022 kg
              Mean distance between the moon’s center and the earth’s center = 3.85 x 10 8 m

   14. A space traveler whose mass is 90kg leaves earth. What are his weight and mass (a) on earth
       and (b) in interplanetary space where there are no nearby planetary objects?

   15. Synchronous communications satellites are placed in a circular orbit that is 3.59 x 10 7 m above
       the surface of the earth. What is the magnitude of the acceleration due to gravity at this
       distance?

   16. Your mass is 70 kg and you weigh 46.5 N more on planet Atrodox than on planet Xenor. Both
       planets have the same radius of 1.33 x 107 m. What is the difference MA – MX in the masses
       of these planets?

   17. If your weight has decreased by half, what is your altitude above the earth’s surface?

   18. A motorcycle is trying to leap across a canyon. Using the principle of Work-Energy Theorem,
       NOT Newton’s Laws or Kinematics, to find the speed with which the cycle will strike the ground
       on the other side. The cycle takes off horizontally from a cliff on one side of the canyon at a
       speed of 40 m/s and at a height of 75 m. The cycle lands at a height of 50 m. Neglect air
       resistance.
   19. A fighter jet is launched from an aircraft carrier with the aid of its own engines and a steam-
       powered catapult. The thrust of its engines is 2.3 x 105 N. In being launched from rest it
       moves through a distance of 87 m and has a kinetic energy of 4.5 x 10 7 J at lift-off. What is the
       work done on the jet by the catapult? If the mass of the jet is 100,000 kg, what is its velocity?

   20. An archer shoots an arrow from the top of a building at a speed of 28 m/s. The building is 40
       m tall. Ignoring air resistance, find the speed with which the arrow strikes the ground when the
       arrow is fires (a) horizontally (b) vertically straight up, and (c) vertically straight down. You
       must use the Work-Energy Theorem, NOT Newton’s Laws or Kinematics.

   21. The President, upon learning of his victory in the recent election, threw the 0.75 kg mug he
       was holding at the time straight up into the air with an initial speed of 18.0 m/s. (a) How high
       would it go if there was no air friction? (b) If the mug rises to a maximum height of only 11.8
       m, determine the magnitude of the average force due to air resistance. You must use the
       Work-Energy Theorem, NOT Newton’s Laws or Kinematics.



Answers: (You should double check with at least 3 other students too because these answers were given by students and
may not necessarily be correct.)

1. 29.53 m/s
2. a) 511 m b) 101 m/s
3. a) 1102.5 m b) 107 s c) 22.58 s d) 221m/s
                      2
4. a) 5.8 s b) 4.9 m/s c) half mass of Earth
5. all same 39.6 m/s
6. No
7. 3.9 m
8. 30 degrees
9. 7.8 m/s
10. 8.6 m/s
11. 1.99 s
12. 234 N
13. 0.0044 N
14. a) 90 kg, 882 N b) 90 kg, 0 N
               2
15. 0.223 m/s
            24
16. 1.76x10 kg
            6
17. 2.64x10 m
18. 45.7 m/s
                   7
19. 30 m/s, 2.5x10 J
20. 39.6 m/s all same
21. a) 16.5 m b) 2.95 N

				
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