Question

A clay ball (mass = 0.25kg) has a rightward momentum of +1.75 kg∙m/s. A second clay ball (mass = 0.25 kg) has a leftward momentum of -1.75 kg∙m/s. The two collide, stick together, and come to a complete stop after the collision.1) What was the total energy of the system before the collision?a- Not enough information to determineb- 6.13 Jc- 0 Jd- 12.25 J2) What was the total energy of the system after the collision?a- 6.13 Jb- 12.25 Jc- Not enough information to determined- 0 J3) What was the total momentum before the collision?a- 6.13 kg∙m/sb- 12.25 kg∙m/sc- Not enough information to determined- 0 kg∙m/s4) What was the total momentum after the collision?a- Not enough information to determineb- 0 kg•m/sc- 6.13 kg•m/sd- 12.25 kg•m/s

Answer 1

1)

$\begin{gathered} E1=\frac{1}{2}m_1v_1^2+\frac{1}{2}m_1v_2^2 \\ where: \\ m_1=m_2=0.25kg \\ v_1=7m/s \\ v_2=-7m/s \\ so: \\ E1=\frac{1}{2}0.25(7^2)+\frac{1}{2}0.25(7^2) \\ E1=6.125+6.125 \\ E1=12.25J \end{gathered}$

Answer:

d. 12.25J

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2)

According to the conservation of energy:

$\begin{gathered} E1=E2 \\ so: \\ E2=12.25J \end{gathered}$

Answer:

b. 12.25

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3)

$P1=m_1v_2+m_2v_2=+1.75-1.75=0$

Answer:

d. 0 kg∙m/s

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4)

Using conservation of momentum:

$\begin{gathered} P1=P2 \\ so: \\ P2=0 \end{gathered}$

Answer:

b. 0 kg•m/s