A 1.00 kg block is attached to a horizontal spring with spring constant 2500 N/m. The block is at rest on a frictionless surface. A 20 g bullet is fired into the block, in the face opposite to the spring and sticks.

What is the bullet's speed if the subsequent oscillations have an amplitude of 10.0 cm?

(Express your answer in m/s as a pure number).

Respuesta :

Answer:

The speed of the bullet is = 27.36 [tex]\frac{m}{s}[/tex]

Explanation:

Mass of the block (M) = 1 kg

Spring constant = 2500 N per meter

Mass of the bullet ([tex]m_{b}[/tex]) = 20 gm = 0.2 kg

Amplitude A = 0.1 m

Now the final velocity of block when bullet is entered into the block is given by

[tex]V_f = \sqrt{\frac{k}{M + m_b} } A[/tex]

[tex]V_f = \sqrt{\frac{2500}{1 + 0.2} } 0.1[/tex]

[tex]V_f =[/tex] 4.56 [tex]\frac{m}{sec}[/tex]

From conservation of momentum principal

[tex]P_{after} = P_ {before}[/tex]

[tex](M+m_{b} )V_f = m_{b} v_b + M v_B[/tex]

Since [tex]v_B = 0[/tex]

1.2 × 4.56 = 0.2 [tex]v_b[/tex]

[tex]v_b[/tex] = 27.36 [tex]\frac{m}{s}[/tex]

Therefore the speed of the bullet is = 27.36 [tex]\frac{m}{s}[/tex]

The speed of the bullet before the collision is 252.45 m/s.

The given parameters;

  • mass of the block, m = 1.0 kg
  • spring constant, k = 2500 N/m
  • mass of the bullet, m = 20 g = 0.02 kg
  • amplitude of the oscillation, A = 10 cm = 0.1 m

The final velocity of the bullet-block system is calculated by applying the principle of conservation of energy;

[tex]K.E = U_x\\\\\frac{1}{2} mv^2 = \frac{1}{2} kA^2\\\\mv^2 = kA^2\\\\v^2 = \frac{kA^2}{m} \\\\v = \sqrt{\frac{kA^2}{m} } \\\\v = \sqrt{\frac{(2500) \times (0.1)^2}{(1 + 0.02)} } \\\\v = 4.95 \ m/s[/tex]

The initial velocity of the bullet is calculated by applying the principle of conservation of linear momentum for inelastic collision as follows;

[tex]m_1 u_1 + m_2u_2 = v(m_1 + m_2)\\\\[/tex]

where;

  • [tex]u_1[/tex] is the initial velocity of the block = 0
  • [tex]u_2[/tex] is the initial velocity of the bullet

[tex]1(0) \ + \ 0.02(u_2) = 4.95(1 + 0.02)\\\\0.02u_2 = 5.049\\\\u_2 = \frac{5.049}{0.02} \\\\u_2 = 252.45 \ m/s[/tex]

Thus, the speed of the bullet before the collision is 252.45 m/s.

Learn more about inelastic collision here: https://brainly.com/question/7694106