Outline for Physics E: Chapter 3 Two Dimensional Motion and Vectors

Lecture Questions:

1) Distinguish between a vector quantity and a scalar quantity. What physics quantities are vectors? Which are not?

2) Draw a picture of two vectors adding graphically and indicate the resulting vector with a double tick mark. Explain how to mathematically find the resulting vector for two vectors that are: a) in the same direction b) in opposite directions c) at right angles to one another. Does the order in which vectors are added make any difference?

3) What is meant by decomposing a vector? What do the components represent? Draw a vector and its components. Mark the components with single tick marks. What is special about perpendicular components?

4) Describe how to mathematically find the resultant for two vectors that are not in the same, opposite or at a right angle direction.

5) Explain how wind and ice surfers are able to move faster than the wind that is pushing them?

6) What is a projectile? Give some examples of projectiles. What are some examples of objects that are not projectiles?

7) Describe the horizontal motion of a projectile. What equations are valid in this direction? Describe the vertical motion of a projectile. What equations are valid in this direction?

8) A projectile is launched horizontally off a cliff. What determines how long the projectile is in the air? Does the horizontal velocity of the projectile change? What is the initial vertical speed of the projectile? What are the horizontal the vertical components of the projectile’s acceleration?

9) A projectile is launched at an angle to the horizontal. Neglecting air resistance and assuming the projectile lands at the same height it was launched what is true of its initial and final vertical velocities? What are the vertical velocity and acceleration at the top of the trajectory? Given the initial velocity and angle how do you find the initial horizontal and vertical velocities?

10) A bag of food is dropped from an airplane flying horizontally. Describe the path of the bag when viewed from an observer on the plane. How about an observer on the ground? If we know the speed of the plane relative to the ground and the speed of a passenger relative to the plane walking forward towards the cockpit, how would we find the speed of the passenger relative to the ground?

Practice Problems:

1) While following directions on a treasure map, a pirate walks 45.0 m north, then turns and walks 7.5 m east. What single straight line displacement could the pirate have taken to reach the treasure?

2) Emily passes a soccer ball 6.0 m directly across the field to Kara, who then kicks the ball directly down the field to Luisa. What is the ball’s total displacement as it travels between Emily and Luisa?

3) A hummingbird flies 1.2 m along a straight line path at a height of 3.4 m above the ground. Upon spotting a flower below, the humming bird drops directly downward 1.4 m to hover in front of the flower. What is the hummingbird’s total displacement and direction?

4) Find the horizontal and vertical components of the 125 m displacement of a superhero who flies down from the top of a tall building at an angle of 25 degrees below the horizontal.

5) A child rides a toboggan down a hill that descends at an angle of 30.5 degrees to the horizontal. If the hill is 23.0 m long what are the horizontal and vertical components of the child’s displacement?

6) A skier squats low and races down an 18 degree ski slope. During a 5 s interval, the skier accelerates at 2.5 m/s2. What are the horizontal and vertical components of the skier’s acceleration during the time interval?

7) A football player runs directly down the field for 35 m before turning to the right at an angle of 25 degrees from his original direction and running an additional 15 m before getting tackled. What is the magnitude and direction of the runner’s total displacement?

8) During a rodeo, a clown runs 8.0 m north, turns 35 degrees east of north and runs 3.5 m. Then, after waiting for the bull to come near, the clown turns due east and runs 5.0 m to exit the arena. What is the clown’s total displacement?

9) A pelican flying along a horizontal path drops a fish from a height of 5.4 m while traveling 5.0 m/s. How far does the fish travel horizontally before it hits the water below?

10) A cat chases a mouse across a 1.0 m high table. The mouse steps out of the way so that the cat slides off the table with a speed of 5.0 m/s. Where does the cat strike the floor?

11) A golfer can hit a golf ball a horizontal distance of over 300 m on a good drive. What maximum height would a 301.5 m drive reach if it were launched at an angle of 25 degrees to the ground?

12) A quarterback throws the football to a receiver who is 31.5 m down the field. A) If the football is thrown at an angle of 40.0 degrees to the ground, at what initial speed must the quarterback throw the ball? B) What is the ball’s highest point during the flight?

13) A spy runs from the front to the back of an aircraft carrier at a speed of 3.5 m/s. If the aircraft carrier is moving forward at 18.0 m/s, how fast does the spy appear to be running when viewed by an observer on a nearby stationary submarine?

14) A pet-supply truck moves at 25.0 m/s north along a highway. Inside, a dog moves at1.75 m/s at an angle of 35 degrees east of north. What is the velocity of the dog relative to the road?

Schedule:

DayClass AssignmentHomework Assignment Due

MondayLab: Projectile StationsNone

TuesdayLecture: Vector Addition and DecompositionNone

WednesdayLecture: Projectile MotionNote Summary

ThursdayPractice ProblemsNote Summary

FridayHW ReviewChp. 3 Q 1-21,22,24,26,28

MondayPractice ProblemsNone

TuesdayLab: Red Rocket Altitude and Initial VelocityNone

WednesdayLab: Red Rocket Target PracticeNone

ThursdayHomework ReviewChp. 3 Q 30-33,34,36,38,40,42, 44,45-49,50,52,54

FridayQuizNotebook

Revised 2016