Physics! Unit 2 Review Constant Acceleration Particle Model

Transcription

1 Physics! Unit 2 Review Constant Acceleration Particle Model Name 1. Use the graph to answer the following questions. a. Describe the motion of the object. b. Determine the of the object from the graph t (s) c. Calculate the object's displacement from 2 to 6 seconds. d. Sketch an appropriate vs. graph for this scenario. 2. A car, initially at rest, accelerates at a constant rate of 4.0 m/s 2 for 6 s. How fast will the car be traveling at t = 6 s? How far did the car travel? (s) 3. A tailback initially running at a of 5.0 m/s becomes very tired and slows down at a uniform rate of 0.25 m/s 2. How fast will he be running after going an additional 10 meters? (s)

2 4. Using the graph compare the following quantities for objects A and B. Is A > B, A < B, or A = B. a. Displacement from 0 to 3 s How do you know? b. Displacement from 0 to 1.5 s How do you know? (m) (s) 3 B A c. Displacement from 1.5 to 3 s How do you know? d. Average from 0 to 3 s How do you know? e. Average from 0 to 1.5 s How do you know? f. Average from 1.5 to 3 s How do you know? g. Which is moving faster at t = 1.5 How do you know? 5. For each of the vs graphs shown below, draw the corresponding v vs t, a vs t, and motion map.

3 6. While cruising along a dark stretch of highway with the cruise control set at 25 m/s ( 55 mph), you see, at the fringes of your headlights, that a bridge has been washed out. You apply the brakes and come to a stop in 4.0s. Assume the clock starts the instant you hit the brakes. a) Construct a motion map that represents the motion described above, including,, and. Clearly demonstrate how you can determine the direction (sign) of the from the motion map representation. b) Sketch a qualitative x vs. t graph and justify how it matches the written description above. c. Construct a quantitatively accurate v vs t graph to describe the situation. d. Using the v vs t graph determine the car s displacement (change in ) during braking. Explain your work and indicate on the graph how it was evaluated. e. Evaluate the v vs t graph to determine the cars. Show your work and explain how the graph was evaluated. f. Make a quantitatively accurate and graph. g. Determine the area under the and graph and justify what this area could represent with units and other information provided about the car.

4 Free Fall 7. A car traveling in a straight line increases its speed from 35 km/hr to 55 km/hr in 5 seconds. Calculate the and label the answer with correct units. 8. On a vs graph, what does the slope represent? 9. On a vs graph, what does the slope represent? 10. On a vs graph, what does the area under the curve represent? 11. Freefall is the condition that occurs when we ignore the effect of air and the only force acting on an object is. 12. Objects in freefall have an of precisely m/s/s, which can be rounded off to m/s/s for mental calculations. 13. How much will the speed of an object thrown upward decrease each second? 14. How much will the speed of an object thrown downward increase each second? 15. How will you calculate the speed an object will have in freefall at some (t) after it is dropped from rest? 16. How fast will an object dropped from rest be traveling after the following amounts of? a. 2 seconds b. 5 seconds c seconds 17. How will you calculate the distance an object will have fallen in freefall at some (t) after it is dropped from rest? 18. Complete the following table for an object in freefall after being dropped from rest Time (s) Speed (m/s) Distance Fallen (m) Acceleration (m/s/s) An object falls freely through a distance of 125 meters and hits the ground. How fast will it be going?

5 UII Challenge problem 1: Speeder and Patrolman Problem. While eating a box of doughnuts and sipping on a cup of coffee, a patrolman observes a driver approaching at a constant 40m/s (80mph). The patrolman instinctively washes down his last mouthful and secures his coffee as the speeder passes. By the the patrolman pulls on the road and accelerates to catch the speeder, 4s have passed. If the patrolman can accelerate at a constant 6m/s/s what will he catch up to the driver assuming the patrolman s original is zero. To receive full credit for this extra credit, you must complete the following. 1. Mathematically solve for the and show all work. 2. Graphically solve for the, show and explain process. 3. Draw a qualitative motion map representing the situation for each object. UII Challenge problem 2: The Velociraptor A complete solution will consist of: a. At least three diagrams or graphs to represent the situation. Use the ones you find most useful. b. A determination of the quantities for which it is possible to solve. c. A complete solution, showing work and graphs to solve for any quantities in part b. A Velociraptor spots you 75 meters away and attacks, accelerating at 4 m/s/s up to its top speed of 20 m/s. When it spots you, you begin to flee, quickly reaching your top speed of 6 m/s in 3 seconds.