September 14th, 2007

physics help energy conservation and projectiles?

sterv asked:


A horizontal BB gun 2.75 m off the ground fires a pebble of mass m at a horizontal velocity of 12 m/s. (a) Use energy conservation to determine the speed of the BB when it hits the ground (b) Use projectile methods to determine how far away the ball landed from the shooter.

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This entry was posted on Friday, September 14th, 2007 at 2:43 pm and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.

2 Responses to “physics help energy conservation and projectiles?”

  1. derith300 Says:
    September 15th, 2007 at 1:52 pm

    See in real life you would just walk over to the bb and measure how far it is from your gun. so much for real life aplications!

  2. Helmut Says:
    September 17th, 2007 at 7:19 am

    (a) (1/2)mv1^2 = (1/2)mv0^2 + mgh
    v1^2 = v0^2 + 2gh
    v1^2 = (12)^2 + 2(9.80665)(2.75)
    v1 ≈ 14.06899 m/s ≈ 14.1 m/s

    (b) h1 = h0 + v0t - (1/2)at^2
    t^2 = 2(2.75)/9.80665
    t ≈ 0.5608439 s ≈ 0.561 s or 561 ms