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DP IB Physics: HL

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Home / IB / Physics: HL / DP / Topic Questions / 6. Circular Motion & Gravitation / 6.1 Circular Motion / Structured Questions


6.1 Circular Motion

Question 1a

Marks: 4

A bung is attached to a rope and a person swings the bung around their head. The bung moves in a horizontal circular path.

(a)
Circle four options from the list below, which are properties of all objects moving in a circle.

 

Period       Heat energy       Electricity       Frequency       Decay constant

Angular displacement       Capacitance       Angular speed       Strangeness
[4]
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    Question 1b

    Marks: 3

    The length of the rope is r, and the bung is moving with velocity v. It is acted upon by force F.

    (b)
    Sketch the shape of the bung's path, labelling r, v and F.
    [3]
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      Question 1c

      Marks: 3

      The bung travels though an angular displacement of pi over 8 rad.

      (c)
      Convert the angular displacement into degrees.
      [3]
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        Question 1d

        Marks: 6

        It takes 0.5 s for the bung to complete one revolution. The radius of its circular path is 0.75 m.

        (d)
         
        (i)
        Calculate the angular speed of the bung.
        [4]
        (ii)
        Calculate the linear speed of the bung.
        [2]
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          Question 2a

          Marks: 4

          A car is moving with uniform circular motion and experiences a centripetal force.

          (a)

           

          (i)
          Define centripetal force.
          [3]
          (ii)
          State the type of force which is responsible for the centripetal force on the car.
          [1]
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            Key Concepts
            Centripetal Force

            Question 2b

            Marks: 2

            The car has mass 500 kg and is travelling around a roundabout with a linear speed of 9 m s−1. The radius of the roundabout is 12 m.

            (b)
            Determine the centripetal force acting on the car.
            [2]
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              Key Concepts
              Centripetal Force

              Question 2c

              Marks: 3

              The car proceeds to another roundabout which has radius 20 m. The angular speed of the car at this roundabout is 0.2 rad s−1.

              (c)
              Calculate the centripetal acceleration of the car around this roundabout.
              [3]
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                Question 2d

                Marks: 2

                At this second roundabout, the car is travelling at the maximum speed possible before it would skid. The coefficient of static friction determines the maximum speed possible and is given by mu subscript s equals fraction numerator omega squared r over denominator g end fraction, where omega is the angular speed, r is the radius of the roundabout,  and g is the acceleration due to gravity.

                (d)
                Determine the co-efficient of static friction between the tyres and the road.
                [2]
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                  Question 3a

                  Marks: 6

                  A planet orbits a star in 260 Earth days, which is 22 464 000 s. 

                  (a)

                   

                  (i)
                  State the angular displacement of the planet in 260 days, giving an appropriate unit with your answer.
                  [2]
                  (i)
                  Calculate the angular speed of the planet.
                  [4]
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                    Question 3b

                    Marks: 2

                    The linear speed of the planet is 35 000 m s−1.

                    (b)
                    Calculate the radius of the planet's orbit.
                    [2]
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                      Question 3c

                      Marks: 2

                      The planet has a mass of 2.7 × 1024 kg and stays in orbit due to a centripetal force.

                      (c)
                       Calculate the centripetal force required to keep the planet in orbit.
                      [2]
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                        Key Concepts
                        Centripetal Force

                        Question 3d

                        Marks: 5

                        The planet experiences a centripetal acceleration.

                        (d)
                         
                        (i)
                        Define uniform centripetal acceleration
                        [3]
                        (ii)
                        Determine the centripetal acceleration experienced by the planet.
                        [2]
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                          Question 4a

                          Marks: 3

                          A fairground ride is moving with uniform circular motion. 

                          (a)
                           
                          (i)
                          Define angular displacement.
                          [2]
                          (ii)
                          Define angular speed.
                          [1]
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                            Question 4b

                            Marks: 4

                            A child on the ride has an angular displacement of pi over 2rad and angular speed of 0.3 rad s−1.

                            (b)
                            Calculate the time required for the child to have this angular displacement.
                            [4]
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                              Question 4c

                              Marks: 2

                              The radius of the ride is 8 m and the child's mass is 35 kg.

                              (c)
                              Determine the centripetal force on the child.
                              [2]
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                                Key Concepts
                                Centripetal Force

                                Question 4d

                                Marks: 4
                                (d)
                                 
                                (i)
                                Calculate the child's linear speed.
                                [2]
                                (ii)
                                Calculate the child's centripetal acceleration.
                                [2]
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                                  Question 5a

                                  Marks: 3

                                  The diagram shows the bath of a ball with two forces acting on it. The ball is attached to a string and is swung in a circle in a vertical plane. Air resistance is negligible.

                                  (a)

                                   

                                  (i)
                                  Label the forces marked on the diagram below:
                                  6-1-q5a-question-sl-sq-easy-phy
                                  [2]
                                  (ii)
                                  State which of these forces provides the centripetal force on the ball.
                                  [1]
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                                    Question 5b

                                    Marks: 2

                                    The centripetal force on the ball is not constant as the ball travels along its circular path.

                                    (b)
                                    Circle the correct words in the sentences below:

                                     

                                    The maximum / minimum magnitude of centripetal force is found at the bottom of the circular path.
                                    The maximum / minimum magnitude of centripetal force is found at the top of the circlular path.
                                    [2]
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                                      Question 5c

                                      Marks: 3

                                      The radius of the circle is 0.8 m, the mass of the ball is 0.5 kg and the linear velocity is 2.4 m s−1.

                                      (c)
                                      Calculate the centripetal force at the bottom of its circular path.
                                      [3]
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                                        Question 5d

                                        Marks: 2

                                        The speed and acceleration of the ball varies as it moves around its circular path.

                                        (d)
                                        Circle the correct words in the sentences below:

                                         

                                        The speed of the ball at the bottom of the circular path will be faster / slower than at the top.

                                        The acceleration at the bottom of the circular path will be at a minimum / maximum compared to the top.

                                        [2]
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