22.23 10月20日国日
$=814$
thepageschool.instructure.com
Canvas Student
En
那开

240910 1: Assignments Unit 4 Homework ,

Home
Sylitous
Modules
Grades

Submission Details
Grade: $7 / 10$

Unit 4 Homework
Cecilia Guo submitted Oct 21 at 12:18pm

Add a Comment:
Opaints caned
A 2 kg object traveling at $5 \mathrm{~m} / \mathrm{s}$ on a frictionless horizontal surface col-Ides head-on with and sticks to a 3 kg object initially at rest. Which of the following correctly identifes the change in total kinetic energy and the resulting speed of the objects after the collision? 5 P149
Media Comment
Attach File
Save

\begin{tabular}{|c|c|}
\hline Kinetic Energy & Speed \
\hline Increases & $2 \mathrm{~m} / \mathrm{s}$ \
\hline
\end{tabular}

\begin{tabular}{|c|c|}
\hline Kinetic Energy & Speed \
\hline Decreases & $2 \mathrm{~m} / \mathrm{s}$ \
\hline
\end{tabular}

\begin{tabular}{|c|c|}
\hline Kinetic Energy & Speed \
\hline Increases & $3.2 \mathrm{~m} / \mathrm{s}$ \
\hline
\end{tabular}
\begin{tabular}{|c|c|c|c|}
\hline \multirow{3}{*}{$ imes$} & \multirow[t]{3}{*}{O} & & \
\hline & & Kinetic Energy & Speed \
\hline & & Decreases & $3.2 \mathrm{~m} / \mathrm{s}$ \
\hline
\end{tabular}
22 23 10月20日国日
- $81 \%$
thepageschool.instructure.com
Canvas Student
En
那开
240910 1: Assignments Unit 4 Homework ,

Home
Syltats
Modules
Grades

Submission Details
Grade: $7 / 10$

Unit 4 Homework
Cecilia Guo submitted Oct 21 at 12:18pm

Add a Comment:
4
65
4)
Media Comment
Attach File
5

Opoints earned
Save

The graph above shows the position x as a function of time for the center of mass of a system of particles of total mass 6.0 kg. For a very short time interval around 2.0 s , an external force is exerted on an object in the system. What is the resulting change in momentum of the system? SP143
$52 \mathrm{~kg} \cdot \mathrm{~m} / \mathrm{s}$
$-18 \mathrm{~kg} \cdot \mathrm{~m} / \mathrm{s}$
$-6 \mathrm{~kg} \cdot \mathrm{~m} / \mathrm{s}$
$6 \mathrm{~kg} \cdot \mathrm{~m} / \mathrm{s}$

6
1 point earred

A 4 kg object moving to the left collides with and sticks to a 3 kg object moving to the right. Which of the following is true of the motion of the combined object $\longrightarrow$
22.23 10月20日用田
thepageschool.instructure.com
Canvas Student
En
那开
240910 1: Assignments Unit 4 Homework

Home
5yluthos
Modules
Grades

2
Opolits earsed
Grade: $7 / 10$
Submission Details
Unit 4 Homework
Cecilia Guo submitted Oct 21 at 12:18pm

Add a Comment:
$10 \mathrm{~m} / \mathrm{s}$
Media Comment
Attach File
Save

On a straight horizontal track along which blocks can slide with negligible friction. block 1 slides toward block 2, which is initially at rest. Block 1 collides with an electronic force probe attached to block 2 . generating a force vs. time graph and causing block 2 to start sliding. What additional measurements must be made to determine the momentum of block 2 after the collision? SP144
The mass of block 2 only
Both the mass and the post-collision speed of block 1
None

The post-collision speed of block 2 only

3
1 point earned

Acart of mass $m$ is moving with negligible friction along a track with known speed $\mathbf{v 1}$ to the right. It collides with and sticks to a cart of mass 4 m moving with known speed $\sqrt{2}$ to the right. Which of the two principles, conservation of momentum and conservation of mechanical energy, must be applied to determine the final speed of the carts, and why? 5P1410

O Only conservation of momentum, because the momentum lost by one cart is gained by the other and there is only one unknown quantify.

Question

22.23 10月20日国日
$=814$
thepageschool.instructure.com
Canvas Student
En
那开

240910 1: > Assignments > Unit 4 Homework ,

Home
Sylitous
Modules
Grades

Submission Details
Grade: $7 / 10$

Unit 4 Homework
Cecilia Guo submitted Oct 21 at 12:18pm

Add a Comment:
Opaints caned
A 2 kg object traveling at $5 \mathrm{~m} / \mathrm{s}$ on a frictionless horizontal surface col-Ides head-on with and sticks to a 3 kg object initially at rest. Which of the following correctly identifes the change in total kinetic energy and the resulting speed of the objects after the collision? 5 P149
Media Comment
Attach File
Save

\begin{tabular}{|c|c|}
\hline Kinetic Energy & Speed \
\hline Increases & $2 \mathrm{~m} / \mathrm{s}$ \
\hline
\end{tabular}

\begin{tabular}{|c|c|}
\hline Kinetic Energy & Speed \
\hline Decreases & $2 \mathrm{~m} / \mathrm{s}$ \
\hline
\end{tabular}

\begin{tabular}{|c|c|}
\hline Kinetic Energy & Speed \
\hline Increases & $3.2 \mathrm{~m} / \mathrm{s}$ \
\hline
\end{tabular}
\begin{tabular}{|c|c|c|c|}
\hline \multirow{3}{*}{$	imes$} & \multirow[t]{3}{*}{O} & & \
\hline & & Kinetic Energy & Speed \
\hline & & Decreases & $3.2 \mathrm{~m} / \mathrm{s}$ \
\hline
\end{tabular}
22 23 10月20日国日
- $81 \%$
thepageschool.instructure.com
Canvas Student
En
那开
240910 1: > Assignments > Unit 4 Homework ,

Home
Syltats
Modules
Grades

Submission Details
Grade: $7 / 10$

Unit 4 Homework
Cecilia Guo submitted Oct 21 at 12:18pm

Add a Comment:
4
65
4)
Media Comment
Attach File
5

Opoints earned
Save

The graph above shows the position x as a function of time for the center of mass of a system of particles of total mass 6.0 kg. For a very short time interval around 2.0 s , an external force is exerted on an object in the system. What is the resulting change in momentum of the system? SP143
$52 \mathrm{~kg} \cdot \mathrm{~m} / \mathrm{s}$
$-18 \mathrm{~kg} \cdot \mathrm{~m} / \mathrm{s}$
$-6 \mathrm{~kg} \cdot \mathrm{~m} / \mathrm{s}$
$6 \mathrm{~kg} \cdot \mathrm{~m} / \mathrm{s}$

6
1 point earred

A 4 kg object moving to the left collides with and sticks to a 3 kg object moving to the right. Which of the following is true of the motion of the combined object $\longrightarrow$
22.23 10月20日用田
thepageschool.instructure.com
Canvas Student
En
那开
240910 1: > Assignments > Unit 4 Homework >

Home
5yluthos
Modules
Grades

2
Opolits earsed
Grade: $7 / 10$
Submission Details
Unit 4 Homework
Cecilia Guo submitted Oct 21 at 12:18pm

Add a Comment:
$10 \mathrm{~m} / \mathrm{s}$
Media Comment
Attach File
Save

On a straight horizontal track along which blocks can slide with negligible friction. block 1 slides toward block 2, which is initially at rest. Block 1 collides with an electronic force probe attached to block 2 . generating a force vs. time graph and causing block 2 to start sliding. What additional measurements must be made to determine the momentum of block 2 after the collision? SP144
The mass of block 2 only
Both the mass and the post-collision speed of block 1
None

The post-collision speed of block 2 only

3
1 point earned

Acart of mass $m$ is moving with negligible friction along a track with known speed $\mathbf{v 1}$ to the right. It collides with and sticks to a cart of mass 4 m moving with known speed $\sqrt{2}$ to the right. Which of the two principles, conservation of momentum and conservation of mechanical energy, must be applied to determine the final speed of the carts, and why? 5P1410

O Only conservation of momentum, because the momentum lost by one cart is gained by the other and there is only one unknown quantify.

Accepted Answer

∻Solution∻ ‖ a ⋮ To find the final speed after the collision, we apply the conservation of momentum. The initial momentum of the system is given by: $$p_{initial} = m_1 v_1 + m_2 v_2$$ where $m_1 = 2 \, \text{kg}$, $v_1 = 5 \, \text{m/s}$, $m_2 = 3 \, \text{kg}$, and $v_2 = 0 \, \text{m/s}$$. Thus, $$p_{initial} = (2 \, \text{kg})(5 \, \text{m/s}) + (3 \, \text{kg})(0) = 10 \, \text{kg m/s}$$. ‖ ‖ b ⋮ After the collision, the two objects stick together, so we can denote their combined mass as \(m_{total} = m_1 + m_2 = 2 \, \text{kg} + 3 \, \text{kg} = 5 \, \text{kg}$. The final momentum $p_{final}$ is equal to the initial momentum: $$p_{final} = m_{total} v_f$$. Setting the initial and final momenta equal gives us: $$10 \, \text{kg m/s} = (5 \, \text{kg}) v_f$$, which simplifies to $$v_f = \frac{10 \, \text{kg m/s}}{5 \, \text{kg}} = 2 \, \text{m/s}$$. ‖ ‖ c ⋮ To find the change in kinetic energy, we calculate the initial and final kinetic energies. The initial kinetic energy is: $$KE_{initial} = \frac{1}{2} m_1 v_1^2 = \frac{1}{2} (2 \, \text{kg}) (5 \, \text{m/s})^2 = 25 \, \text{J}$$. The final kinetic energy after the collision is: $$KE_{final} = \frac{1}{2} m_{total} v_f^2 = \frac{1}{2} (5 \, \text{kg}) (2 \, \text{m/s})^2 = 10 \, \text{J}$$. The change in kinetic energy is: $$\Delta KE = KE_{final} - KE_{initial} = 10 \, \text{J} - 25 \, \text{J} = -15 \, \text{J}$$, indicating a decrease in kinetic energy. ‖ ∻Answer∻ ***D*** ∻Key Concept∻ ⚹ Conservation of Momentum: The total momentum of a closed system remains constant if no external forces act on it. The equation is $$p_{initial} = p_{final}$$. Kinetic Energy: The energy of motion, given by $$KE = \frac{1}{2} mv^2$$. ⚹ ∻Explanation∻ ⚹ In this collision, momentum is conserved, leading to a final speed of 2 m/s, while kinetic energy decreases due to the inelastic nature of the collision. ⚹\)

Sia