PHYSICS 20 KINEMATICS PRACTICE EXAM

Transcription

1 Choose the best response and place your answers, using HB pencil, on the LXR sheet provided. You must include your student number and the version number of the test. 1. A student wants to set up an experiment to show how frictional forces effect the velocity of cars. In this experiment, the manipulated variable is a. time b. friction c. velocity d. position 2. A student made these inferences about position, distance, and displacement. 1. The position of an object has a reference point and direction. 2. The displacement of an object is the length of the route travelled. 3. The distance an object travels can be less than its displacement. 4. The displacement of an object is its change in position. Which statements represent valid inferences about position, distance, and displacement? a. 1 and 2 b. 1 and 4 c. 2 and 3 d. 3 and 4 3. Which of the following is a scalar quantity? a. velocity b. gravity c. temperature d. position 4. Which length is the largest? a cm b m c. 1 x 10 2 mm d. 1 m e. none of these. 5. If an object is travelling at a constant velocity, which quantity would not remain constant over the same time intervals? a. displacement b. acceleration c. distance travelled d. position 6. Which of the following statements concerning vertical motion is incorrect? a. an object thrown horizontally will take as long to reach the ground as an object that is dropped from the same height b. the actual velocity of a falling object will always be less than the calculated value if air resistance is not taken into account c. the actual velocity of a falling object approximates Galileo's description for part of its flight and Aristotle's description for the last part of its flight d. the direction of acceleration due to gravity is always opposite the direction of motion 7. Which set of data supports the inference that velocity is constant during uniform motion? a. b. c. d.

2 8. What amount of time will be required for an electron travelling at 3.0 x 10 6 m/s to travel the 340 km displacement between Calgary and Edmonton? a. 1.1 x 10-1 s b. 1.1 x 10-4 s c. 8.8 x 10 3 s d x 10-5 s 9. This question and the following question refer to the graph below which shows the displacement of a basketball player as a function of time as he runs up and down the court along a north-south line. (x = 0 is at the center line and +x is toward the north.) What is the average velocity of the basketball player during the time interval from time t = 1 s to time t = 6 s? a. -3 m/s b. -1/6 m/s c. +3/5 m/s d. +1/2 m/s e. -2/5 m/s 10. A car traveling at 22.4 m/s skids to a stop in 2.55 s. Determine the skidding distance of the car (assume uniform acceleration). a m b m c km d m 11. In an experiment, a ball was rolled down a wooden ramp which was fixed at an angle of 30 o. The distance that the ball rolled was measured every two seconds. In this experiment, which two variables are controlled? a. Time and slope b. Time and distance c. Slope and friction d. Slope and distance 12. Which position as a function of time graph best represents a negative acceleration? a. b. c. d. e. f.

3 Each of the following questions is worth 1 mark. Exact answers are required. Only the solution will be marked. 1. Starting from rest, an object rolls freely down an incline that is 10.0 m long in 2.00 s. The acceleration of the object is b x 10 w m. The value of b is (Record your answer to three digits) 2. The SR-71 Blackbird is the one of the fastest aircraft, having attained a speed of 3.66 x 10 3 km/h. If this aircraft, initially travelling at 250 km/h, blasts its engines and begins accelerating at 21.6 m/s 2, the distance required to reach a speed of 3.66 x 10 3 km/h can be written in the form a.bc x 10 d m. The values of a, b, c, and d, respectively are,,, and. (Record all four digits of your answer on the answer sheet.) 3. Use the following information to answer the question 30 Speed vs Time speed m/s I II III IV time (s) The displacement of the object during the section marked II is m. (Record your answer to two digits)

4 For each of the following questions complete communication must be shown. Communication consists of an introduction to the physics of the situation, diagrams, word explanations and supporting calculations in a well laid out formula, substitution, answer format. 1. Construct a position, velocity, time table for every second for an object accelerating at -2.0 m/s 2 from a position 30 m to the east with an initial velocity of 5.00 m/s east. Make your table for the first six seconds. (5 marks) Position (m) Velocity (m/s) Time (s) For each of the following explain the physics concept by which you arrive at your solution: a) Explain the difference between the terms position, displacement and distance travelled. Give an example for each by referencing the table. b) Calculate the average velocity of the motion? c) What will the position of the object be at time 3.75 s?

5 Score Description 5 Explanations show an excellent understanding of the physics principles and cover the full scope of the question. Calculations follow a format of: concept stated, relevant variable isolated, substitution with appropriate numerical values, and an answer which both states relevant units and respects significant digits. Vector questions show a complete, labeled, vector diagram. There may be one small numerical mistake, but there are no mistakes in physics understanding. 4 Explanations show a very good understanding of the physics principles involved but contain a significant misstatement. Alternately, the answer has two numerical mistakes which significantly affect the answer. Alternately, the presentation of the solution is unorganized and very difficult to follow. Alternately, a 2-dimensional vector problem is lacking a completely labeled vector diagram. 3 Explanations show a good understanding of the physics principles involved but are disjointed or contain irrelevant and/or incorrect statements. The answer makes good progress towards solving the problem. Alternately, there are two major mistakes which significantly affect the solution. Alternately, the answer is correct but the work shown is not sufficient support. Alternately, a 2-dimensional vector problem is lacking a vector diagram. 2 The answer shows a limited understanding of the physics necessary to solve the question. There is some progress towards solving the question but there are significant calculation and/or understanding issues. 1 The answer shows a very limited understanding of the physics necessary to solve the question but there is at least one relevant statement which begins to address the problem. 0 There has been no attempt to solve the problem or the solution is invalid for the question.

6 2. Using your graphing calculator, draw a graph for the following motion and then answer the questions below. For each response, explain the physics concept by which you arrived at your answer. (10 marks) a) Develop a complete calculator graph and show the relevant information on the page. b) What is the position of the object after s? c) What is the velocity of the object at time t = s? d) What is the projected displacement of the object from time t= to t = s? e) What is the acceleration of the object

7 Score Description 10-9 Explanations show an excellent understanding of the physics principles and cover the full scope of the question. Calculations follow a format of: concept stated, relevant variable isolated, substitution with appropriate numerical values, and an answer which both states relevant units and respects significant digits. Vector questions show a complete, labeled, vector diagram. There may be small errors in calculation but there are no errors in physics understanding. 8-7 Explanations show a very good understanding of the physics principles involved but contain a significant misstatement or are incomplete. The answer is mostly complete and correct. Alternately, the answer has two numerical mistakes which significantly affect the answer. Alternately, the presentation of the solution is unorganized and very difficult to follow. Alternately, a 2-dimensional vector problem is lacking a completely labeled vector diagram. 6-5 Explanations show a good understanding of the physics principles involved but are disjointed or contain irrelevant and/or erroneous statements. The answer makes good progress towards solving the problem. Alternately, there are two major calculation mistakes which significantly affect the solution. Alternately, the answer is correct but the work shown is not sufficient support. Alternately, a 2-dimensional vector problem is lacking a vector diagram. 4-3 The answer shows a limited understanding of the physics necessary to solve the question. There is some progress towards solving the question but there are significant calculation and/or understanding issues. 2-1 The answer shows a very limited understanding of the physics necessary to solve the question but there is at least one relevant statement which begins to address the problem. 0 There has been no attempt to solve the problem or the solution is invalid for the question.