Figure 4 shows a child playing with a toy train. The train is on a bridge. When the child lets go of the train, the train rolls down the bridge. The momentum of the train at the bottom of the bridge is 0.216 kg·m/s mass of the train = 180 g Calculate the velocity of the train at the bottom of the bridge. Use the Physics Equations Sheet. Velocity = _____ m/s The train collides with a stationary carriage on the track. Explain why the velocity of the train after the collision is less than it was before the collision. Use ideas about momentum in your answer.

GCSE AQA Physics Combined Science Momentum: Figure 4 shows a child playing w

Figure 4 shows a child playing with a toy train - AQA - GCSE Physics Combined Science - Question 3 - 2022 - Paper 2

Question 3

Figure 4 shows a child playing with a toy train. The train is on a bridge. When the child lets go of the train, the train rolls down the bridge. The momentum of t... show full transcript

Worked Solution & Example Answer:Figure 4 shows a child playing with a toy train - AQA - GCSE Physics Combined Science - Question 3 - 2022 - Paper 2

Step 1

Calculate the velocity of the train at the bottom of the bridge.

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Answer

To find the velocity of the train, we use the formula for momentum: $p = mv$ Where:

$p$ is the momentum (0.216 kg·m/s)
$m$ is the mass in kg (180 g = 0.180 kg)
$v$ is the velocity in m/s.

Substitute the known values into the formula: $0.216 = 0.180 \cdot v$
Rearranging gives: $v = \frac{0.216}{0.180}$
Calculating this yields: $v = 1.2 \text{ m/s}$

Thus, the velocity of the train at the bottom of the bridge is 1.2 m/s.

Step 2

Explain why the velocity of the train after the collision is less than it was before the collision.

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Answer

The total momentum is conserved in a collision. This means that the momentum of the train before the collision is equal to the momentum of the train plus the stationary carriage after the collision:

During the collision, the momentum of the carriage increases because it starts moving and gains momentum.
Consequently, the momentum of the train decreases as it transfers some of its momentum to the stationary carriage.

Since momentum is defined as: $\text{momentum} = \text{mass} \times \text{velocity},$ it follows that if the mass of the train remains constant but some of its velocity is transferred to the carriage, the velocity of the train must decrease.

Figure 4 shows a child playing with a toy train - AQA - GCSE Physics Combined Science - Question 3 - 2022 - Paper 2

Worked Solution & Example Answer:Figure 4 shows a child playing with a toy train - AQA - GCSE Physics Combined Science - Question 3 - 2022 - Paper 2

Calculate the velocity of the train at the bottom of the bridge.

Explain why the velocity of the train after the collision is less than it was before the collision.

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