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def Force(x, v, t):
    """
    This function defines the force acting on a simple pendulum
    """
    
    # import libraries
    
    import numpy as np

    # constants (see homework writeup):

    # damping coefficient
    A = 0.1
    
    # restoring force coefficient
    B = 2.
    
    # driving force ampitude and frequency
    C = 2.0
    OMEGA = 1.2

    F = -A * v -B * np.sin(x) + C * np.sin(OMEGA * t)
    
    return F

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