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PY205N Name (print)__________________________________ Spring 2011 TEST 1, version P (practice) ID# ________________________________ Time limit: 75 minutes for entire test Closed book Section#_____________________________
HONOR CODE I have neither given nor received unauthorized aid on this test. Signed:_____________________
General information and instructions: On the blank Scantron sheet, (1) print and bubble in your name where indicated in the upper right corner; then (2) do the same with your ID number where indicated near the top left; then (3) bubble in your test version A or B on line 70. The test consists of two parts: A, 15 multiple-choice problems worth 5 points each; and B, show-your-work problems worth 25 points total.
Part A, multiple-choice: Bubble in your answers on the Scantron sheet lines 1-15. You may write on part A, but your work in part A will not be graded.
- The mean distance from the earth to the moon is 3.82 × 108 m. Assuming that your highway speed is a fast 40 m/s (~90 mi/hr), to one significant figure the number of (earth) days required to “drive” to the moon is (a) 100 days (b) 200 days (c) 700 days (d) 1000 days (e) 2000 days
- A particle of mass m has a speed v. The SI unit for the combination mv^2 is (a) N m/s, where N is the SI unit of force (b) N m (c) kg m/s (d)kg m^2 /s (e)kg s^2 /m
3.In a total time of 1.5 s, a billiard ball rolls 2.00 m in the positive x direction, strikes a cushion head-on, then rebounds 0.5 m in the − x direction. The average velocity of the ball in this time interval is (a) 0.83 m/s in the positive x direction (b) 1.70 m/s in the positive x direction (c) 1.50 m/s in the positive x direction (d) 0.50 m/s in the positive x direction (e) 1.00 m/s in the positive x direction
- A billiard ball rolls in the positive x direction, strikes a cushion head-on, and rebounds. Just before striking the cushion its velocity is 2.00 m/s in the positive x direction. Just after rebounding its velocity is 1.80 m/s in the negative x direction. The change in the velocity of the ball is (a) 0.20 m/s in the positive x direction (b) 0.20 m/s in the negative x direction (c) 3.80 m/s in the negative x direction (d) 1.90 m/s in the positive x direction (e) 3.80 m/s in the positive x direction
- A car starts from rest and accelerates uniformly in a straight line to a speed of 40 m/s in 10 s. The acceleration and distance traveled during this 10 s interval is (a) 2.0 m/s 2 and 200 m (b) 2.0 m/s^2 and 100 m (c) 4.0 m/s 2 and 100 m (d) 4.0 m/s^2 and 200 m (e) 4.0 m/s 2 and 400 m
- A particle is moving parallel to the x axis with a velocity v = − 6 t + 2 t^2 , where v is in m/s and t is in s. The acceleration of the particle is zero at t = (a) never (b) 1.5 s (c) 3.0 s (d) 4.5 s (e) 0.5 s
- A boy stands at the edge of the flat roof of a building and throws a rock vertically upward with an initial speed of 24 m/s. Some time later the rock passes a window 15 m below the point where the rock was released. Assuming free-fall condition and no air resistance, the velocity v when the rock passes the window is (a) 24 m/s downward (b) 41 m/s downward (c) 34 m/s downward (d) 19 m/s downward (e) 29 m/s downward
- A river flows due east with a current of 9 m/s. You travel west (upstream) 300 m on a boat that moves 12 m/s relative to the water. The time required for your trip is (a) 100 s (b) 14 s (c) 25 s (d) 33 s (e) 29 s
- Crate A is stacked on top of crate B as shown in the diagram. They rest on the bed of a pickup truck that is moving to the right and gaining speed. Both A and B move with the truck (no sliding). Neglecting air resistance, the best description of the free-body diagram of crate A is (a) gravity acting downward (b) gravity acting downward and a normal force acting upward (c) gravity acting downward, a normal force acting upward, and friction acting to the left (d) gravity acting downward, a normal force acting upward, and friction acting to the right (e) gravity acting downward, a normal force acting downward, and friction acting to the right
- A bucket of water is whirled in a circle in a vertical plane. The radius of the circle is 0.85 m. The minimum speed that will just prevent the water from falling out of the bucket when it is upside down at the top of the circle is (a) 0.2 m/s (b) 0.9 m/s (c) 1.6 m/s (d) 2.2 m/s (e) 2.9 m/s
- A hockey puck is given an initial speed of 17 m/s and comes to rest in 6.5 s. The coefficient of kinetic friction between the puck and the ice is (a) 0. (b) 0. (c) 0. (d) 0. (e) 1.
PY205N Name (print)__________________________________ Spring 2011 TEST 1, version P (practice) ID# ________________________________ Time limit 75 minutes for entire test Closed book Section#_____________________________ HONOR CODE I have neither given nor received unauthorized aid on this test. Signed:_____________________
Part B, show-your-work (2 problems): Work the following problems, providing enough detail so we can follow what you are doing. Show all steps if necessary. If a question requires a numerical answer, draw a box around your answer. Make sure that you include units. Partial credit will be given for incomplete or partially incorrect answers. Write legibly – we cannot give credit if we cannot read your writing.
- The drawing to the right below shows 3 forces pulling in different directions on a crate (not shown). All the forces are in the horizontal plane.
(a) (5 points) Calculate to 3 significant figures the x and y components of the 500 N force
(b) (5 points) Calculate to 3 significant figures the x and y components of the 600 N force
(c) (5 points) Calculate to 3 significant figures the magnitude and direction of the total (net) force. Specify the direction with respect to the positive x axis.
Key: 1a, 2b, 3e, 4c, 5d, 6b, 7e, 8a, 9d, 10b, 11c, 12a, 13d, 14e, 15b
Part B, show your work:
1a: Take components and add. For the 500 N force F x = 399 N in the positive x direction, and F x = 301 N in the positive y direction.
1b: Take components and add. For the 600 N force F x = 361 N in the negative x direction, and F x = 479 N in the positive y direction.
1c: Add the respective components of all 3 forces. F x = 38 N in the positive (^) x direction, and F y = 380 N in the positive y direction. The magnitude is 382 N and the angle with respect to the x axis is 84.3 degrees.
2a: The equation is y = (10 m/s) t − (4.9 m/s 2 ) t^2.
2b: The equation is x = (17.3 m/s) t.
