---
title: "Robin Hood, whose mass is \\( 78.6 \\) \\( \\text{kg} \\), is holding a \\( 6.28 \\) \\( \\text{m} \\) long rope that has been pulled back \\( 42.35^{\\circ} \\) from the vertical. He will swing like a pendulum until reaching the lowest point of the arc, at which point he grabs a hanging bag of coins of mass \\( 12.3 \\) \\( \\text{kg} \\). Immediately upon grabbing the coins, he releases the rope and continues forward as a projectile toward a lake surface below. The release point of the rope is \\( 9.72 \\) \\( \\text{m} \\) above the water level. The local gravitational field strength is \\( 6.90 \\) \\( \\text{m/s}^2 \\)."
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url: "https://nerd-notes.com/ubq/105996/"
date_modified: "2026-08-18T02:39:34+00:00"
---

# Robin Hood, whose mass is \( 78.6 \) \( \text{kg} \), is holding a \( 6.28 \) \( \text{m} \) long rope that has been pulled back \( 42.35^{\circ} \) from the vertical. He will swing like a pendulum until reaching the lowest point of the arc, at which point he grabs a hanging bag of coins of mass \( 12.3 \) \( \text{kg} \). Immediately upon grabbing the coins, he releases the rope and continues forward as a projectile toward a lake surface below. The release point of the rope is \( 9.72 \) \( \text{m} \) above the water level. The local gravitational field strength is \( 6.90 \) \( \text{m/s}^2 \).

Robin Hood, whose mass is \( 78.6 \) \( \text{kg} \), is holding a \( 6.28 \) \( \text{m} \) long rope that has been pulled back \( 42.35^{\circ} \) from the vertical. He will swing like a pendulum until reaching the lowest point of the arc, at which point he grabs a hanging bag of coins of mass \( 12.3 \) \( \text{kg} \). Immediately upon grabbing the coins, he releases the rope and continues forward as a projectile toward a lake surface below. The release point of the rope is \( 9.72 \) \( \text{m} \) above the water level. The local gravitational field strength is \( 6.90 \) \( \text{m/s}^2 \).

**Part a)** Determine the speed of Robin right before he grabs the coins. *(3 points)*

**Part b)** Determine the speed of Robin (Robin plus coins) immediately after he grabs the coins. *(3 points)*

**Part c)** Determine the total horizontal distance traveled from the moment he lets go of the rope until he reaches the water surface. *(3 points)*


*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/105996/*