Physics Chapter 7: Motion
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Questions and Answers

What determines the position of an object in motion?

  • The time of observation
  • The mass of the object
  • The speed of the object
  • The reference point (correct)

    • Which scenario illustrates the concept of relative motion?

  • A book lying still on a desk.
  • A car moving at 60 km/h on a highway.
  • A train appearing to move while the observer is in another stationary train. (correct)
  • A child running in a playground.

    • In the context of discussing motion, what can be inferred from erratic motion?

  • It poses potential dangers to individuals. (correct)
  • It usually leads to beneficial outcomes.
  • It is a common occurrence in nature.
  • It can be easily controlled and managed.

    • What role does a reference point play in describing the motion of an object?

    <p>It represents the origin of the object.</p> Signup and view all the answers

    How is controlled motion beneficial, based on the information provided?

    <p>It can generate energy, like hydroelectric power.</p> Signup and view all the answers

    What is the total distance covered when an object moves from point O to A and then back to O?

    <p>120 km</p> Signup and view all the answers

    What does velocity specify in addition to speed?

    <p>Direction of motion</p> Signup and view all the answers

    What is the magnitude of displacement when the object moves from O to C through A and then returns to O?

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

    When going from point O to A, what are the distance and displacement values, respectively?

    <p>60 km distance, 60 km displacement</p> Signup and view all the answers

    How is average velocity calculated when the velocity is changing uniformly?

    <p>By taking the arithmetic mean of initial and final velocity</p> Signup and view all the answers

    Can an object that has moved through a distance have zero displacement?

    <p>Yes, if the object returns to its starting point.</p> Signup and view all the answers

    What will be the magnitude of displacement of a farmer moving along the boundary of a square field with each side measuring 10 m after 2 minutes and 20 seconds?

    <p>20 m</p> Signup and view all the answers

    What is the average speed of an object that travels 32 m in 6 s?

    <p>5 m s-1</p> Signup and view all the answers

    What physical quantity requires only a numerical value and not a direction to be described?

    <p>Distance</p> Signup and view all the answers

    Which of the following units measure both speed and velocity?

    <p>Both A and B</p> Signup and view all the answers

    Which statement about displacement is true?

    <p>Displacement can be zero.</p> Signup and view all the answers

    In the journey from O to B and back to C, what is the distance covered?

    <p>120 km</p> Signup and view all the answers

    How can you determine if an object's motion is uniform or non-uniform?

    <p>By comparing distances covered in equal time intervals.</p> Signup and view all the answers

    If an object’s speed increases and its direction changes, what happens to its velocity?

    <p>It varies</p> Signup and view all the answers

    Which statement accurately describes the relationship between distance and displacement?

    <p>Displacement can be zero while distance is not.</p> Signup and view all the answers

    What is the shortest distance measured from an initial to a final position of an object called?

    <p>Displacement</p> Signup and view all the answers

    Based on the data provided for objects A and B, which statement is correct?

    <p>Both objects are in non-uniform motion.</p> Signup and view all the answers

    How is the total path length covered by the object calculated in the example?

    <p>By adding the distances for each segment of the journey</p> Signup and view all the answers

    What does a distance-time graph represent?

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

    What is the shape of the distance-time graph for an object moving at uniform speed?

    <p>A straight sloped line</p> Signup and view all the answers

    How is speed determined using a distance-time graph?

    <p>By finding the slope of the distance-time graph</p> Signup and view all the answers

    What can be inferred from a horizontal line in a distance-time graph?

    <p>The object is at rest</p> Signup and view all the answers

    What happens to the distance represented by the graph when an object travels equal distances in equal intervals of time?

    <p>The graph is a straight line</p> Signup and view all the answers

    What does the graph of an object moving at uniform velocity look like?

    <p>A straight line parallel to the x-axis</p> Signup and view all the answers

    What does the shape of a distance-time graph indicate when the object is in non-uniform motion?

    <p>The distance shows non-linear variation with time</p> Signup and view all the answers

    What does a distance-time graph show on its axes?

    <p>Time on the x-axis and distance on the y-axis</p> Signup and view all the answers

    In a velocity-time graph, what is represented along the x-axis?

    <p>Time</p> Signup and view all the answers

    What is the unit of acceleration in the examples given?

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

    If a car's velocity readings every 5 seconds are: 0, 2.5, 5.0, 7.5, 10.0, 12.5, 15.0 m/s, what kind of motion is this demonstrating?

    <p>Uniformly accelerated motion</p> Signup and view all the answers

    At 20 seconds, what is the velocity of the car in km/h based on the provided data?

    <p>36 km/h</p> Signup and view all the answers

    In the first case described, what is the initial velocity of Rahul's bicycle?

    <p>0 m/s</p> Signup and view all the answers

    If a bus decreases its speed from 80 km/h to 60 km/h in 5 seconds, what type of acceleration is occurring?

    <p>Negative acceleration</p> Signup and view all the answers

    What was the acceleration of the bicycle during the time Rahul applied brakes?

    <p>-0.4 m/s²</p> Signup and view all the answers

    What represents non-uniform acceleration?

    <p>A ball rolling down a hill with increasing speed</p> Signup and view all the answers

    What is the final velocity of the bicycle after Rahul paddles for 30 seconds?

    <p>6 m/s</p> Signup and view all the answers

    What type of graph helps in solving problems with two variables?

    <p>Line graph</p> Signup and view all the answers

    What shape does the velocity-time graph take for uniformly accelerated motion?

    <p>Straight line</p> Signup and view all the answers

    How is the distance travelled by the car determined from its velocity-time graph?

    <p>By calculating the area under the graph</p> Signup and view all the answers

    What is the primary difference between speed and velocity?

    <p>Speed is a scalar quantity, while velocity is a vector quantity.</p> Signup and view all the answers

    Under which condition are average speed and average velocity equal?

    <p>When an object moves in a straight line with constant speed.</p> Signup and view all the answers

    What does the area ABCD under the velocity-time graph signify when the car moves at a uniform velocity?

    <p>The total distance from A to C</p> Signup and view all the answers

    Which of the following describes the velocity-time graph for non-uniformly accelerated motion?

    <p>It can have any shape</p> Signup and view all the answers

    What does the odometer in a vehicle specifically measure?

    <p>The distance traveled by the vehicle.</p> Signup and view all the answers

    What does the term 'magnitude of displacement' refer to in the context of a velocity-time graph?

    <p>The total area under the velocity-time graph</p> Signup and view all the answers

    What characterizes the path of an object in uniform motion?

    <p>The object covers equal distances in equal intervals of time.</p> Signup and view all the answers

    If a signal from a spaceship took five minutes to reach a ground station, what is the distance covered by the signal traveling at the speed of light ($3 imes 10^8 ext{ m/s}$)?

    <p>9.0 x 10^15 m</p> Signup and view all the answers

    What is the average speed of a car that travels 400 km in 8 hours?

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

    In Usha's swim, what is her average velocity for covering 180 m in one minute?

    <p>0 m/s</p> Signup and view all the answers

    What happens to velocity during uniform motion along a straight line?

    <p>It remains constant.</p> Signup and view all the answers

    What does the variable 'u' represent in the equations of motion?

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

    Which equation represents the relationship between final velocity, initial velocity, and acceleration?

    <p>$v = u + at$</p> Signup and view all the answers

    How is acceleration calculated using the first equation of motion?

    <p>$a = \frac{(v - u)}{t}$</p> Signup and view all the answers

    For an object moving with a uniform acceleration, which statement about distance is accurate?

    <p>Distance can be calculated using $s = ut + \frac{1}{2}at^2$.</p> Signup and view all the answers

    What is the derived equation that relates the position and velocity of an object?

    <p>$v^2 = u^2 + 2as$</p> Signup and view all the answers

    Study Notes

    Motion Overview

    • The walls of a classroom can be considered at rest as they do not change position.
    • The perception of motion can be relative; for example, when sitting in a train, the world outside appears to move due to the train's own movement.

    Types of Motion

    • Erratic motion, like during an earthquake, can be dangerous, while controlled motion, such as in hydroelectric power generation, provides benefits.
    • The position of an object is described using a reference point, known as the origin.

    Straight Line Motion

    • Motion in a straight line is the simplest form of movement.
    • Distance measures the total length of the path traveled, while displacement refers to the shortest distance from the initial to the final position.
    • Displacement can be zero if an object returns to its starting position, even if distance traveled is not.

    Distinction Between Distance and Displacement

    • Distance is non-directional and can be greater than or equal to displacement.
    • Displacement is a vector quantity; it has both magnitude and direction.

    Uniform vs. Non-Uniform Motion

    • Uniform motion occurs when an object covers equal distances in equal time intervals.
    • Non-uniform motion occurs when an object covers unequal distances over equal time intervals, common in everyday scenarios like driving in traffic.

    Measuring Motion

    • Velocity combines the aspect of speed with direction and can be uniform (constant value) or variable (changing speed or direction).

    Average Speed and Velocity

    • Average speed is total distance divided by total time, while average velocity takes the direction into account.
    • Odometer measures total distance traveled without considering direction.

    Graphical Representation

    • Distance-time graphs illustrate the relationship between distance and time, indicating rest, uniform speed, or non-uniform speed.
    • Velocity-time graphs display how an object's velocity changes over time, with straight lines indicating uniform motion.

    Acceleration

    • An object is said to be in uniform acceleration if its velocity changes at a constant rate.
    • Acceleration can be positive (speeding up) or negative (slowing down).

    Equations of Motion

    • Three key equations relate displacement, velocity, acceleration, and time:
      • ( v = u + at )
      • ( s = ut + \frac{1}{2}at^2 )
      • ( 2as = v^2 - u^2 )

    Practical Examples

    • Example of average speed: A car covers 400 km in 8 hours yields an average speed of 50 km/h.
    • Usha swims in a pool, covering 180 m in 1 minute, resulting in an average speed of 3 m/s, while her displacement is 0 m.

    Velocity Variation

    • For uniformly accelerated motion, the velocity-time graph is linear; the area under the graph represents the distance traveled.
    • Non-uniformly accelerated motion produces varied graph shapes, indicating changing acceleration.

    Calculating Motion Parameters

    • Understanding motion allows for calculations concerning distance, time, acceleration, and speed, providing insight into real-life scenarios such as vehicle movement and sports activities.

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    Description

    Explore the concepts of motion and rest through engaging activities. Discuss real-life experiences, such as trains appearing to move while stationary, and the effects of controlled versus erratic motion in our lives. Get ready to think critically about your surroundings!

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