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    A trolley of mass 850 g is held between two fixed points by means of identical springs
    When the trolley is in equilibrium, the springs are each extended by 4.5 cm. Each spring has a
    spring constant of 16 N m-1.
    i) Calculate the total energy stored in the two springs when the trolley is in equilibrium.
    The trolley is moved a distance of 1.5 cm along the direction of the springs. This causes the
    extension of one spring to be increased and the extension of the other spring to be decreased. The
    trolley is then released. The trolley accelerates and reaches its maximum speed at the equilibrium
    position. Calculate:
    ii) the total energy stored in the two springs before the trolley is released;
    iii) the kinetic energy of the trolley when it returns to the equilibrium position;
    iv) the maximum speed of the trolley
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    When the trolley moves 1.5cm, how does the extension of the two springs change? You (should) have an equation for the energy stored in an extended spring. Calculate the energy stored in the springs now using the extensions you've jsut worked out. Be careful, because your spring constant is given in Newtons/metre and your extension is in cm.

    When the spring gets back to equilibrium position (1) that's where its maximum velocity is and (2) the springs are back to 4.5cm extension. Calculate the energy stored in the springs now - it should be less than you got first time. That extra energy has provided the KE. You should now also be able to find the max speed.
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    (Original post by rsk)
    When the trolley moves 1.5cm, how does the extension of the two springs change? You (should) have an equation for the energy stored in an extended spring. Calculate the energy stored in the springs now using the extensions you've jsut worked out. Be careful, because your spring constant is given in Newtons/metre and your extension is in cm.

    When the spring gets back to equilibrium position (1) that's where its maximum velocity is and (2) the springs are back to 4.5cm extension. Calculate the energy stored in the springs now - it should be less than you got first time. That extra energy has provided the KE. You should now also be able to find the max speed.
    I'm still a little confused with the latter part of the question how would I find the velocity of the trolly after its release to work out the kinetic energy
    And how would I use this equation to work out max speed
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    You find the kinetic energy first, then use this to find the speed.

    When the trolley is moved 1.5cm, the total energy stored in the springs is GREATER than when it is at equiibrium and both springs at 4.5cm.

    So, work out the energy stored in the springs in these two situations, and since energy is conserved, the KE at equilibrium is equal to the difference between these.
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    (Original post by rsk)
    You find the kinetic energy first, then use this to find the speed.

    When the trolley is moved 1.5cm, the total energy stored in the springs is GREATER than when it is at equiibrium and both springs at 4.5cm.

    So, work out the energy stored in the springs in these two situations, and since energy is conserved, the KE at equilibrium is equal to the difference between these.
    Oooohhhh okay yeah I understand now thanks a million 😀😀
 
 
 
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