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AP physics MOTION questions looking for help

  1. Sep 17, 2005 #1
    hi, i am having problems on these questions below.. if you can spend some time doing these and help me, it will be greatly appreciated. If you get a chance, showing the work won't hurt :)

    1. In 1940, Emanuel Zacchini flew about 53 m as a human cannonball, a record that remains unbroken. His initial velocity was 24.2 m/s at an angle theta. What is the maximum height h Emanuel achieved during the record flight? (Ignore air resistance.)

    A. If the position of a particle is given by x = 20t – 5t2, where x is in meters and t is in seconds, when, if ever, is the particle’s velocity zero?
    B. When is its acceleration zero?
    C. When is a negative?

    4. A hot air balloonist drops an apple over the side while the balloon is accelerating upward at 4.0 m/s2 during liftoff.

    A. What is the apple's acceleration once it is released?
    B. If the velocity of the balloon is 2 m/s upward at the instant of release, what is the apple's velocity then?

    5. A stone is thrown horizontally from the top of a 24 m tower. It hits the ground 18 m from the base of the tower.
    A. What is the initial velocity of the stone?
    B. When is the velocity of the stone just before it hits the ground?

    6. A projectile is launched with an initial speed of 30 m/s at an angle of 60o above the horizontal. Calculate the magnitude and direction of its velocity
    A. at 2.0 s after launch.
    B. at 5.0 s after launch.

    7.A brick is thrown upward from the top of a building at an angle of 25o to the horizontal and with an initial speed of 15 m/s. If the brick is in flight for 3.0 s, how tall is the building?

    9. A rocket is launched at an angle of 53.0o above the horizontal with an initial speed of 100 m/s. It moves for 3.00 s along its initial line of motion with an acceleration of 30.0 m/s2. At this time its engines fail and the rocket proceeds to move as a projectile.

    A. What is the maximum altitude reached by the rocket?

    B. What is its total time of flight?

    C. What is its horizontal range?

    10. A car is parked on a cliff overlooking the ocean on an incline that makes an angle of 24.0o below the horizontal. The negligent driver leaves the car in neutral, and the emergency brakes are defective. The car rolls from rest down the incline with a constant acceleration of 4.00 m/s2 for a distance of 50.0 m to the edge of the cliff. The cliff is 30.0 m above the ocean.

    A. What is the car’s position relative to the base of the cliff when the car lands?
    B. How long is the car in the air?

    if you know any of these, any help will be greatly appreciated :) thanks in advance.
  2. jcsd
  3. Sep 17, 2005 #2


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    We are willing to help you, not do the work for you, so tell us about your attempts and explain why you are having problems with a specific problem.
    As far as question 3 is concerned you need do differentiate the equation once w.r.t. time to get the equation for the velocity as a function of time. Differrentiating it again will give you the acceleration of the object as a function of time.
  4. Sep 17, 2005 #3

    Chi Meson

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    4a is an easy "recognize the concept" question that involves no calculation.
  5. Sep 17, 2005 #4


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    Science Advisor

    So is 4b!!
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