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Open Question: i have a physics test tomorrow and i do not understand this concepts! help please?
January 24th, 2010 by wood

1. A clam dropped by a seagull takes 3.0 seconds to hit the ground. What is the seagull’s approximate height above the ground at the time the clam was dropped?
15 m
30. m
45 m
90. m

2.A cannon with a muzzle velocity of 500. meters per second fires a cannonball at an angle of 30.° above the horizontal. What is the vertical component of the cannonball’s velocity as it leaves the cannon?
0.0 m/s
250. m/s
433 m/s
500. m/s

what answers did you get and how do i do it? what formals do i use? ur help is greatly appreciated!


One Response  
  • Rajesh writes:
    January 27th, 2010 at 9:29 am

    For Question 1.
    We have three equation:
    v = u + at
    s = ut + 1/2at^2 (^ is raise to power)
    v^2 – u^2 = 2as

    Here v = final velocity
    u = initial velocity
    a = acceleration
    t = time
    s = distance

    You must remember above three equation.

    For above problem
    acceleration is gravity i.e. g = 9.8m^2/s
    initial velocity u = 0
    time t = 3 sec

    We apply second equation
    s = 0 x 3 + 1/2 x 9.8 x 3
    s = 1/2 x 9.8 x 3
    s = 14.7 m

    For second problem
    Use trigonometry equation

    /
    /
    / 500 m/s
    /
    /_30 deg_____________

    For horizontal velocity
    sin 30 deg = v(hor)/v
    or
    v(hor) = v x sin 30 deg
    = 500 x (square root 3)/2
    = 433 m/s

    For vertical velocity
    cos 30 deg = v(vert)/v
    or
    v(vert) = v x cos 30 deg
    = 500 x 1/2
    = 250 m/s


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