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  • Calculating Initial Velocity with Kinetic Friction: A Physics Problem
    Here's how to solve this problem:

    1. Understand the Forces

    * Friction: The only horizontal force acting on the object is kinetic friction, which opposes its motion.

    * Newton's Second Law: The object's acceleration is caused by the net force acting on it.

    2. Set up the Equations

    * Friction Force: F_friction = μ * N (where μ is the coefficient of kinetic friction and N is the normal force)

    * Normal Force: Since the table is horizontal, the normal force is equal to the object's weight: N = mg (where m is mass and g is acceleration due to gravity, approximately 9.8 m/s²)

    * Newton's Second Law: F_net = ma (where a is the acceleration)

    3. Solve for Acceleration

    * Since the only force acting horizontally is friction, F_net = F_friction.

    * Combining the equations: μ * mg = ma

    * Canceling mass (m) on both sides: μ * g = a

    * Calculate the acceleration: a = 0.3 * 9.8 m/s² = 2.94 m/s²

    4. Use Kinematics to Find Initial Velocity

    * We know:

    * final velocity (v_f) = 0 m/s (comes to rest)

    * time (t) = 1.3 s

    * acceleration (a) = -2.94 m/s² (negative since it's slowing down)

    * Use the kinematic equation: v_f = v_i + at

    * Solve for initial velocity (v_i): v_i = v_f - at

    * Plug in the values: v_i = 0 - (-2.94 m/s²)(1.3 s) = 3.82 m/s

    Therefore, the initial velocity of the object was 3.82 m/s.

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