n the railroad accident, a boxcar weighting 200 kN and traveling at 3 m/s on horizontal track slams into a stationary caboose weighting 400

Question

n the railroad accident, a boxcar weighting 200 kN and traveling at 3 m/s on horizontal track slams into a stationary caboose weighting 400 kN. The collision connects the caboose to the car, and then both move together and you have found the final velocity. Apparently, initial kinetic energy of the system changes (in part, because of friction present). How much energy (in kJ) is transferred from kinetic energy to other forms of energy (e..g., thermal) in the collision

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Ngọc Diệp 3 years 2021-09-05T03:21:34+00:00 1 Answers 17 views 0

Answers ( )

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    2021-09-05T03:22:55+00:00

    Answer:

    ΔK = -6 10⁴ J

    Explanation:

    This is a crash problem, let’s start by defining a system formed by the two trucks, so that the forces during the crash have been internal and the moment is preserved

    initial instant. Before the crash

            p₀ = m v₁ + M 0

    final instant. Right after the crash

            p_f = (m + M) v

            p₀ = p_f

            mv₁ = (m + M) v

            v = \frac{m}{m+M} \  v_1

         

    we substitute

            v = \frac{20}{20+40}   3

            v = 1.0 m / s

    having the initial and final velocities, let’s find the kinetic energy

            K₀ = ½ m v₁² + 0

            K₀ = ½ 20 10³ 3²

            K₀ = 9 10⁴ J

            K_f = ½ (m + M) v²

            K_f = ½ (20 +40) 10³  1²

            K_f = 3 10⁴ J

    the change in energy is

           ΔK = K_f – K₀

           ΔK = (3 – 9) 10⁴

           ΔK = -6 10⁴ J

    The negative sign indicates that the energy is ranked in another type of energy

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