Physics Vector Magnitude and Direction
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Questions and Answers

What is the value of the magnitude R calculated from the vectors?

  • 37 m/s (correct)
  • 40 m/s
  • 30 m/s
  • 25 m/s
  • What angle θ does the resultant vector R make with the vertical?

  • 25°
  • 19° (correct)
  • 12°
  • 35°
  • How should the boy hold his umbrella to achieve the correct angle with the vertical?

  • Vertically upwards
  • At 19° towards the east (correct)
  • At 45° towards the east
  • At 19° facing west
  • What are the x- and y-components of a general vector A represented as A1 and A2?

    <p>A1 = Ax, A2 = Ay</p> Signup and view all the answers

    Which of the following describes a unit vector?

    <p>A vector of unit magnitude with no dimension</p> Signup and view all the answers

    Which method is used to resolve a vector into two component vectors?

    <p>Using unit vectors aligned along the axes</p> Signup and view all the answers

    What is true about the components Ax and Ay of vector A?

    <p>Both are real numbers and not vectors</p> Signup and view all the answers

    If vector A is resolved into A1 and A2, what can be inferred about their direction?

    <p>They lie in the same plane as A</p> Signup and view all the answers

    What does instantaneous velocity represent?

    <p>The limiting value of average velocity as the time interval approaches zero</p> Signup and view all the answers

    In the context of velocity, what does the symbol ∆r represent?

    <p>The change in position of an object</p> Signup and view all the answers

    What happens to the average velocity as the time interval ∆t approaches zero?

    <p>It approaches the instantaneous velocity</p> Signup and view all the answers

    What is the significance of the tangent line in relation to instantaneous velocity?

    <p>It shows the direction of instantaneous velocity</p> Signup and view all the answers

    In the figures representing average velocity, how are the time intervals ∆t1, ∆t2, and ∆t3 characterized?

    <p>They decrease in size</p> Signup and view all the answers

    What is the relationship between ∆t and ∆r as ∆t approaches zero?

    <p>∆r approaches zero</p> Signup and view all the answers

    If the velocity is not constant, what happens to the average velocity as you take shorter time intervals?

    <p>It can become equal to the instantaneous velocity</p> Signup and view all the answers

    Which of the following accurately describes the average velocity within a given time interval?

    <p>It is calculated by dividing displacement by time interval</p> Signup and view all the answers

    What does Equation (3.24a) represent in the context of motion in a plane?

    <p>The Law of Cosines</p> Signup and view all the answers

    How is the direction of motion expressed in relation to the resultant according to Equations (3.24e) and (3.24f)?

    <p>Through tangent and sine relationships</p> Signup and view all the answers

    What do the variables A, B, and θ represent in the context of the equations found?

    <p>Components of a vector</p> Signup and view all the answers

    In the equation for displacement, ∆r = r' – r, what does r' signify?

    <p>The final position vector</p> Signup and view all the answers

    Which of the following accurately describes the resultant of the vectors involved according to Equations (3.24e) and (3.24f)?

    <p>It involves both sine and cosine relationships</p> Signup and view all the answers

    What is the primary purpose of using vectors in describing motion in a plane based on the context provided?

    <p>To represent direction and magnitude of movement</p> Signup and view all the answers

    What does the notation r = x i + y j indicate?

    <p>A position vector in two-dimensional space</p> Signup and view all the answers

    What angle is represented by φ in the equations provided?

    <p>The angle between vector A and vector B</p> Signup and view all the answers

    What is the expression for the x-component of vector A in terms of A and the angle θ?

    <p>Ax = A cos θ</p> Signup and view all the answers

    How is the resultant vector R expressed in terms of components Rx and Ry?

    <p>R = Rx i + Ry j</p> Signup and view all the answers

    What does the formula ∆r = r' − r represent?

    <p>The displacement from one position to another</p> Signup and view all the answers

    What is the limit of average velocity v as ∆t approaches zero?

    <p>The instantaneous velocity of the object</p> Signup and view all the answers

    In the context of motion in a coordinate system, what does the vector v represent?

    <p>The tangent velocity of the object's path</p> Signup and view all the answers

    If an object's position is given by r = x i + y j, what are the components of the displacement ∆r?

    <p>∆r = (x' - x) i + (y' - y) j</p> Signup and view all the answers

    What is the relationship between Ax, Ay, and A in terms of vector components?

    <p>A = /Ax^2 + Ay^2</p> Signup and view all the answers

    If the velocities v_x, v_y, and v_z are defined, what does their representation in unit vector notation imply?

    <p>Velocity can be represented as a combination of i, j, and k for each coordinate</p> Signup and view all the answers

    What is the net displacement of the cyclist after completing the round trip from the center O to the edge P and back to O?

    <p>0 km</p> Signup and view all the answers

    What is the average speed of the cyclist if the total distance covered during the round trip is 2 km in 10 minutes?

    <p>12 km/h</p> Signup and view all the answers

    After how many turns will the motorist's displacement be less than the total path length covered according to the described movement?

    <p>After the eighth turn</p> Signup and view all the answers

    What is the average speed of the taxi if it covers a circuitous path of 23 km in 28 minutes?

    <p>50 km/h</p> Signup and view all the answers

    How high above the ground can the cricketer throw a ball if he can throw it to a maximum horizontal distance of 100 m?

    <p>25 m</p> Signup and view all the answers

    What is the magnitude of acceleration of a stone being whirled in a circular path with a radius of 80 cm making 14 revolutions in 25 seconds?

    <p>8.0 m/s²</p> Signup and view all the answers

    What is the average velocity of the taxi over the distance of 10 km when it takes a circuitous path of 23 km?

    <p>10 km/h</p> Signup and view all the answers

    What is the maximum horizontal distance a ball can go without hitting the ceiling of a hall that is 25 m high when thrown with a speed of 40 m/s?

    <p>200 m</p> Signup and view all the answers

    Study Notes

    Vector Magnitude and Direction

    • Resultant vector R has a magnitude of 37 m/s, calculated as ( R = \sqrt{vr^2 + vw^2} = \sqrt{35^2 + 12^2} ).
    • The angle θ formed with the vertical is approximately 19°, calculated using ( \tan θ = \frac{vw}{vr} = \frac{12}{35} ).
    • Umbrella should be held at approximately 19° with the vertical towards the east to account for wind.

    Vector Resolution

    • A vector can be resolved into two component vectors along designated directions, labeled as λa and μb.
    • Unit vectors (magnitude of one) are often used for vector resolution in a rectangular coordinate system for simplicity.
    • General vector A can be expressed as ( A = Ax \hat{i} + Ay \hat{j} ), where:
      • Ax = A cos(θ)
      • Ay = A sin(θ)

    Position Vector and Displacement

    • Position vector ( r ) of a particle in a plane is defined as ( r = x \hat{i} + y \hat{j} ).
    • Displacement ( Δr ) is determined by the difference between two position vectors, ( Δr = r' - r ).

    Velocity and Average Velocity

    • Instantaneous velocity ( v ) is defined as the limit of average velocity as the time interval approaches zero: ( v = \lim_{Δt \to 0} \frac{Δr}{Δt} ).
    • Average velocity is represented as the direction of the tangent to the path at any point.

    Vector Addition

    • For vectors A and B in the x-y plane, their sum R can be expressed as ( R = R_x \hat{i} + R_y \hat{j} ), where:
      • ( R_x = A_x + B_x )
      • ( R_y = A_y + B_y )

    Displacement and Average Speed

    • The average speed of an object is defined as total distance divided by total time taken.
    • Net displacement occurs when an object returns to its starting point regardless of the path taken.

    Applications

    • Motion analysis for a cyclist in a circular path, with calculations for net displacement, average speed, and average velocity.
    • Situational problems involving a cab ride compared to direct distance highlight differences in average speed versus velocity.
    • The maximum horizontal distance for trajectories considering height restrictions can be calculated based on speed and flight time.

    Circular Motion

    • For projectile motions and circular motion, acceleration can be deduced from radius and rotational speed considerations.
    • Examples include calculating the maximum height a ball can reach based on its throw distance and the characteristics of circular motion of an aircraft.

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    Description

    Test your understanding of vector magnitude and direction with this quiz. It covers topics such as resultant vectors, vector resolution, and displacement in a two-dimensional plane. Perfect for those studying physics concepts in motion and forces.

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