A group of particles of total mass 35 kg has a total kinetic energy of 313 J. The kinetic energy relative to the center of mass is 81 J. What is the speed of the center of mass?

Respuesta :

Answer:

The speed of center of mass is 3.64 m/s.

Explanation:

Given that,

Total mass of the group of particles, m = 35 kg

Total kinetic energy of group of particles, [tex]K_T= 313 J[/tex]

The kinetic energy relative to the center of mass is, K = 81 J

We need to find the speed of center of mass. We know that the total kinetic energy is equal to the sum of rotational kinetic energy and the rotational kinetic energy.

[tex]K_T=E+K\\\\E=K_T-K[/tex]

Since, [tex]E=\dfrac{1}{2}mv_c^2[/tex], [tex]v_c[/tex] is the speed of center of mass

[tex]\dfrac{1}{2}mv_c^2=K_T-K\\\\v_c=\sqrt{\dfrac{2(K_T-K)}{m}} \\\\v_c=\sqrt{\dfrac{2(313-81)}{35}}\\\\v_c=3.64\ m/s[/tex]

So, the speed of center of mass is 3.64 m/s.

The speed of the center of mass will be "3.64 m/s".

Kinetic energy

According to the question,

Total mass, m = 35 kg

Total Kinetic energy, [tex]K_T[/tex] = 313 J

K.E relative to the mass, K = 81 J

We know the relation,

→ Total kinetic energy ([tex]K_T[/tex]) = E + K ...(Equation 1)

or,

         E = [tex]K_T[/tex] + K ...(Equation 2)

here,

E = [tex]\frac{1}{2}[/tex]m[tex]v_c[/tex]²

By substituting "E" in "Equation 2",

→ [tex]\frac{1}{2}[/tex]m[tex]v_c[/tex]² = [tex]K_T[/tex] - K

        [tex]v_c[/tex] = [tex]\sqrt{\frac{2(K_T-K)}{m} }[/tex]

By substituting the values,

            = [tex]\sqrt{\frac{2(313-81)}{35} }[/tex]

            = 3.64 m/s

Thus the above answer is correct.

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