Calculate the final speed of a 100-kg rugby player who is initially running at 7.00 m/s but collides head-on with a padded goalpost and expe

Question

Calculate the final speed of a 100-kg rugby player who is initially running at 7.00 m/s but collides head-on with a padded goalpost and experiences a backward force of 15 kN for 50 ms.

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Delwyn 3 years 2021-08-31T05:35:38+00:00 1 Answers 10 views 0

Answers ( )

  1. thucuc
    0
    2021-08-31T05:36:44+00:00
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    Given Information:  

    Mass = m = 100 kg

    Time = Δt = 50 ms

    Initial speed = Vi = 7.00 m/s

    Force = F = 15 kN

    Required Information:  

    Final speed = Vf = ?

    Answer:  

    Vf  = -0.5 m/s

    Explanation:  

    As we know the Impulse is given as

    I = -FΔt

    Where negative sign indicates backward force

    I = -15,000*0.050

    I = -750

    From the impulse-momentum relation, we can write

    I = mVf – mVi

    Where Vf is the final speed of the rugby player and Vi is his initial speed

    mVf = I + mVi

    Vf = (I + mVi)/m

    Vf = (-750 + 100*7)/100

    Vf = -0.5 m/s

    Therefore, the final speed of the rugby player is -0.5 m/s

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