Question

multiple choice

1. which factor gives the greatest momentum?

a) 70 kg swimmer at 3 m/s
b) 0.5 kg ball at 30 m/s
c) 0.01 kg bullet at 600 m/s
d) 1000 kg car at 0.5 m/s

1. crumple zones reduce collision forces by:

a) decreasing time of impact
b) increasing time of impact
c) increasing velocity change
d) decreasing mass of vehicle

1. which seatbelt provides best protection?

a) lap belt
b) two-point belt
c) three-point belt
d) no belt

short answer

1. a truck (2400 kg) moves at 15 m/s. calculate momentum.

1. a 2000 kg car at 30 m/s takes 10 s to stop. calculate braking force.

1. why do airbags inflate in 0.03 s?

1. name two road features redesigned for safety (e.g., guardrails, crash cushions).

Explanation:

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<reasoning>

Calculate momentum values for Question 1

\[

$$\begin{aligned} &p_A = 70 \text{ kg} \times 3 \text{ m/s} = 210 \text{ kg}\cdot\text{m/s} \\ &p_B = 0.5 \text{ kg} \times 30 \text{ m/s} = 15 \text{ kg}\cdot\text{m/s} \\ &p_C = 0.01 \text{ kg} \times 600 \text{ m/s} = 6 \text{ kg}\cdot\text{m/s} \\ &p_D = 1000 \text{ kg} \times 0.5 \text{ m/s} = 500 \text{ kg}\cdot\text{m/s} \\ &p_D > p_A > p_B > p_C \end{aligned}$$

\]

Analyze conceptual safety questions (Questions 2, 3, 6, 7)

\[

$$\begin{aligned} &\text{Q2: Crumple zones increase impact duration } \Delta t \text{ to reduce force } F = \frac{\Delta p}{\Delta t}. \\ &\text{Q3: Three-point belts distribute force across the torso and pelvis, offering maximum restraint.} \\ &\text{Q6: Airbags must fully inflate before the occupant's body moves forward to strike the interior.} \\ &\text{Q7: Guardrails (absorb energy) and crash cushions (attenuate impact kinetic energy).} \end{aligned}$$

\]

Compute numerical values for Questions 4 and 5

\[

$$\begin{aligned} &\text{Q4: } p = m \cdot v = 2400 \text{ kg} \times 15 \text{ m/s} = 36000 \text{ kg}\cdot\text{m/s} \\ &\text{Q5: } F = \frac{\Delta p}{\Delta t} = \frac{0 - (2000 \text{ kg} \times 30 \text{ m/s})}{10 \text{ s}} = -6000 \text{ N} \quad (\text{Magnitude} = 6000 \text{ N}) \end{aligned}$$

\]
</reasoning>

<answer>

No.	Answer
2	(B) Increasing time of impact
3	(C) Three-point belt
4	\(36000 \text{ kg}\cdot\text{m/s}\)
5	\(6000 \text{ N}\)
6	To fully deploy before the occupant's body moves forward and collides with the interior.
7	Guardrails and crash cushions

</answer>

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Answer:

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"Collision Safety",
"Vehicle Safety Systems",
"Seatbelt Mechanics",
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</pre_analysis>

<reasoning>

Calculate momentum values for Question 1

\[

$$\begin{aligned} &p_A = 70 \text{ kg} \times 3 \text{ m/s} = 210 \text{ kg}\cdot\text{m/s} \\ &p_B = 0.5 \text{ kg} \times 30 \text{ m/s} = 15 \text{ kg}\cdot\text{m/s} \\ &p_C = 0.01 \text{ kg} \times 600 \text{ m/s} = 6 \text{ kg}\cdot\text{m/s} \\ &p_D = 1000 \text{ kg} \times 0.5 \text{ m/s} = 500 \text{ kg}\cdot\text{m/s} \\ &p_D > p_A > p_B > p_C \end{aligned}$$

\]

Analyze conceptual safety questions (Questions 2, 3, 6, 7)

\[

$$\begin{aligned} &\text{Q2: Crumple zones increase impact duration } \Delta t \text{ to reduce force } F = \frac{\Delta p}{\Delta t}. \\ &\text{Q3: Three-point belts distribute force across the torso and pelvis, offering maximum restraint.} \\ &\text{Q6: Airbags must fully inflate before the occupant's body moves forward to strike the interior.} \\ &\text{Q7: Guardrails (absorb energy) and crash cushions (attenuate impact kinetic energy).} \end{aligned}$$

\]

Compute numerical values for Questions 4 and 5

\[

$$\begin{aligned} &\text{Q4: } p = m \cdot v = 2400 \text{ kg} \times 15 \text{ m/s} = 36000 \text{ kg}\cdot\text{m/s} \\ &\text{Q5: } F = \frac{\Delta p}{\Delta t} = \frac{0 - (2000 \text{ kg} \times 30 \text{ m/s})}{10 \text{ s}} = -6000 \text{ N} \quad (\text{Magnitude} = 6000 \text{ N}) \end{aligned}$$

\]
</reasoning>

<answer>

No.	Answer
2	(B) Increasing time of impact
3	(C) Three-point belt
4	\(36000 \text{ kg}\cdot\text{m/s}\)
5	\(6000 \text{ N}\)
6	To fully deploy before the occupant's body moves forward and collides with the interior.
7	Guardrails and crash cushions

</answer>

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