First Semester Review for Physics

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Adele Cunningham
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1 First Semester Review for Physics Learning goals are written in italics, practice exercises are numbered. You will find the equations on the last page. Show work for all calculations by writing Given, Find, Equation in term of the unknown, substitution of values with units and Check. Section 1.1 Reaction Time Describe reaction time 1. Explain why a race car driver needs a faster reaction time than someone driving in a school zone. In your answer, make sure to describe what reaction time is. Describe the effect of distractions on reaction time 2. Even though teenagers often have good reaction times, why is auto insurance more expensive for teenage drivers that it is for older, more experienced drivers? Section 1.2 Measurement Describe uncertainties in measurements 3. Explain what is meant by uncertainty in measurements? Describe and explain the differences in accuracy and precision. 4. Produce a set of measurements that are a. Accurate, but not precise. Make sure to explain why you did what you did. b. Precise, but not accurate. Make sure to explain why you did what you did. Describe the difference between random and systematic errors in measurements. Give an example of systematic error in a set of measurements, and an example of random error in a set of measurements. Section 1.3 Average Velocity Describe motion in terms of strobe pictures 6. Describe the motion that generated the following strobe images (the marks were made using the same time interval): 7. Sketch the strobe pictures, taken every second, of an Unidentified Flying Object (UFO) that moved at constant speed to the right for seconds, increased its speed constantly to the right for the next 6 seconds, and kept moving to the right but accelerating constantly slowing down for the last 7 seconds.

2 Describe d vs. t graphs in terms of relative speed (fast, slow) and direction (away, towards) 8. Describe the motion followed by a rabbit on your yard given the following graph. Imagine the sensor (origin) is next to your garden s door. Use away and towards to describe direction, and constant, speeding up or slowing down to describe speed and acceleration. Distance (m) Time (s) 9. Sketch the distance vs. time graph for a fishermen s boat on late Monona that moves away from the dock at a constant speed for minutes. Suddenly comes to a stop, and returns to the dock at constant but much faster speed to grab the fishing poles that were left on the dock. distance (m) Time 8 (minutes) Build a velocity vs. time graph and an acceleration vs. time graph from a distance vs. time graph using the idea of the slope.. Construct the velocity vs. time and the acceleration vs. time graph for the following distance vs. time graph Distance (m) Time 20 (s) -

3 2 2 Velocity (m/s) Time (s) acceleration (m/s 2 ) Time (s) -2-2 Define in words, and equation: average and instantaneous, velocity and speed. Differentiate between them. 11. Explain the difference between velocity and speed 12. Explain why is it possible for a truck that collects milk from farms to have an average velocity of 20.0 miles/hour if when its minimum speed while in motion was 30.0 miles/hour Solve problems around average velocity using the correct equation by writing Given, Find, Equation in term of the unknown, substitution of values with units and Check. 13. Find the average velocity of a race car that starts 1 m behind the starting point and is 0 m in front of the starting point 3 seconds later. 14. Calculate the time it takes a police cruiser to cover 0.0 km at an average speed of 80.0 km/h. Section 1.4: Average Acceleration Define average acceleration in words and equation 1. Explain what happens to the velocity of an object that starts from rest and accelerates at -m/s 2 Solve problems around average acceleration using the correct equation by writing Given, Find, Equation in term of the unknown, substitution of values with units and Check. 16. What is the final velocity after 3.0 seconds of an object that accelerates at -9.8 m/s 2? 17. A motionless space craft begins to fall towards an exoplanet (a planet outside of our planetary system). Calculate the average acceleration if given that it reaches 0 m/s in just 3.0 s Section 1.: Stopping distance Define stopping, braking and reaction distances 18. Jami embarking on a grand fishing adventure in Sturgeon Bay is driving north. While watching for deer, she is driving a conservative mph (24.6m/s). She sees a deer approximately 0 m in front of her. In class, Jami measured her reaction time at 0.23s. The average pickup truck has a maximum braking acceleration of -7.9 m/s 2. She slams her foot on the brakes and narrowly avoids hitting the deer. a. Draw a diagram illustrating stopping distance, braking distance and reaction distance in this situation.

4 Describe factors that affect stopping, braking and reaction distances 19. List the factors that affect stopping, braking, and reaction distances. 20. If Jami s reaction time was greater, how does that affect stopping distance, reaction distance and braking distance? Solve problems for stopping, braking and reaction distances 21. Determine Jami s reaction distance, stopping distance, and braking distance. Section 1.6 Stop Zones and Go Zones Define go, stop, dilemma and overlap zone 22. Define the above terms. Be able to draw diagrams illustrating these terms and how they are measured. Describe factors that affect go and stop zones 23. List the factors that affect the go zone. List the factors that affect that affect the stop zone. Which factors affect both stop zone and the go zone? Calculate stop and go zones 24. A 1.3-m intersection has a yellow light time of.0s. If the speed limit on the road is 3 mph, calculate the go zone and the stop zone for the intersection. Assume that the cars that travel on the road have an average braking acceleration of -.0m/s 2 and that the average driver has a reaction time of 1.0s. Determine if intersection is safe based on overlap and dilemma zones 2. Is the intersection described in the problem above safe or unsafe? Defend your answer using the overlap and dilemma zone model. 26. (multiple choice) To make an intersection safer, the go zone needs to and the stop zone needs to. a. Increase, decrease b. Decrease, increase c. Increase, increase d. Decrease, decrease Describe changes to factors that would make an intersection safer or more dangerous 27. Of the five factors that affect go zone and stop zone, which factors can an engineer easily change to make an intersection safer? (Hint: there are two) 28. For each of these factors, explain how an engineer could change them to make an intersection safer. Section 1.7 Centripetal Force Describe and give 3 examples of a force.

5 29. Describe and give 3 examples of a force. Describe centripetal force, and explain what the centripetal force is on a car making a turn. 30. Describe centripetal force, and explain what the centripetal force is on a car making a turn. Calculate the speed of an object moving in a circle. 31. A student is spinning a turntable with a wooden block (much like you did in class). The block is located 7. cm from the center, and makes turns every minute. What is the speed of the block in cm/s? Describe what affects centripetal force for an object in a curve 32. Explain what happened to the centripetal force on a car in a curve if a. The speed of the car in increased or decreased. b. The radius of the curve is greater or smaller. Section 2.1 Newton s First law Explain what inertia is and how we measure it. 33. Explain why increasing the speed of an object does not increase the inertia of an object. Describe Newton s 1 st Law of motion. 34. Using Newton s 1 st Law, explain why a soccer ball when kicked will eventually come to a stop, instead of going on forever. Explain what is meant by frame of reference and provide a situation that illustrates this. 3. A train is moving at 1 m/s to the right. A person on the train throws a ball at m/s to the right. a. What speed would the people on the train measure for the thrown ball? b. What speed would a person standing outside the train measure for the thrown ball? Section 2.2 Newton s First law Explain difference between average and instantaneous velocities 36. Provide a scenario in which the average speed of a runner is greater than its instantaneous speed Solve problems around average acceleration 37. What is the acceleration of an object whose velocity goes from m/s to 30 m/s in s? 38. What would be the final velocity for a swimmer that accelerates at 3 m/s 2 from an initial velocity of - m/s after 4 s? Section 2.3 Newton s Second law Differentiate between mass and weight of an object 39. Explain the difference between mass and weight of an object 40. Explain how can the weight of an object change while the mass remains constant?

6 Describe Newton s Second Law 41. According to Newton s second law, if I want two objects of different mass to have the same acceleration, which object should receive a stronger force, the more massive or least massive? Use Newton s second law to calculate mass, acceleration, and force on an object Calculate the weight, mass, or acceleration due to gravity 42. Determine the mass of the tennis ball that accelerates from rest at 200 m/s 2 when a force of 143 N is applied. 43. Determine the weight of an object with 3 kg of mass if its speed increases downwards 9.8 m/s every second when in free fall. Identify the units used to describe forces 44. What is the equivalent of 1 Newton in terms of kilograms, seconds and meters 4. Explain how could you figure out the equivalence of 1 Newton in terms of kilograms, seconds and meters by looking at Newton s Second Law (F=ma) Explain the need for significant figures by describing precision and uncertainty 46. Use the words precision and uncertainty to explain why 23s * 1 = 200s 47. Determine the number of significant figures for: a. 0 b..004g c. 01 kg d. 00 s Apply significant figures to all calculations 48. Find the answer with the correct number of significant figures a. 46 m * m = b. 00 N /2. Kg = c... = d mm * 1 mm = e m f N g (Honor)Add force vectors acting at right angles or parallel to each other. 49. Two players on a rugby scrum push against each other. One pushes with 300 N to the right of the field, and the other with 200 N. What is the net force (include direction)? 0. What is the resultant force on a swimmer that propels herself with 400 N to the north if she is swimming on a sea current that pushes her with 10 N to the East? Sections 4 and Describe the difference between free fall and projectile motion Draw and describe the position vs time of a projectile and an object in free fall 1. If a projectile is fired horizontally and another is dropped at the same time, which one will hit the ground first? Draw a diagram to defend your answer and explain your answer in words.

7 Describe how vertical and horizontal motions are connected in projectile motion Identify the force acting on a projectile Identify the vertical acceleration on a projectile Identify the horizontal acceleration on a projectile Describe the factors that affect the time a projectile stays in the air. Describe the factors that affect the range of a projectile. Predict the angle that will provide the maximum range for a projectile when launched from the ground. (Honors)Resolve velocity of an object into its vertical and horizontal components 2. A football is kicked at 9. m/s at an angle of 70 o. Determine the horizontal and vertical velocity. (Honors) Calculate a,vi, Vf, d, t for a projectile at any point in the path of the projectile. 3. Calculate the maximum height, time in the air and range for the following situations. a. A ball dropped from a height of.0m b. A ball thrown in the air at a velocity of 3.0m/s at a height of.0m. c. A ball thrown horizontally at a speed of 3.0m/s at a height of.0m. d. A ball thrown from the ground at a speed of 3.0m/s at an angle of 1 o. e. A ball thrown at a height of.0m at a speed of 3.0 m/s at an angle of 1 o.

3.3 Acceleration An example of acceleration Definition of acceleration Acceleration Figure 3.16: Steeper hills

3.3 Acceleration An example of acceleration Definition of acceleration Acceleration Figure 3.16: Steeper hills 3.3 Acceleration Constant speed is easy to understand. However, almost nothing moves with constant speed for long. When the driver steps on the gas pedal, the speed of the car increases. When the driver