/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 57 \(Apollo\) astronauts took a "ni... [FREE SOLUTION] | 91Ó°ÊÓ

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\(Apollo\) astronauts took a "nine iron" to the Moon and hit a golf ball about 180 m. Assuming that the swing, launch angle, and so on, were the same as on Earth where the same astronaut could hit it only 32 m, estimate the acceleration due to gravity on the surface of the Moon. (We neglect air resistance in both cases, but on the Moon there is none.)

Short Answer

Expert verified
The acceleration due to gravity on the Moon is approximately 1.74 m/s².

Step by step solution

01

Understanding the Projectile Motion Formula

The distance a projectile travels can be described by the equation \( R = \frac{v_0^2 \sin(2\theta)}{g} \), where \( R \) is the range, \( v_0 \) is the initial velocity, \( \theta \) is the launch angle, and \( g \) is the acceleration due to gravity. Here, the same swing and launch angle implies that \( v_0 \) and \( \theta \) are constants for both Earth and Moon.
02

Relating Earth and Moon Distances

On Earth, the range \( R_E \) is 32 m, and on the Moon, the range \( R_M \) is 180 m. The equation relating these is \( \frac{R_E}{R_M} = \frac{g_E}{g_M} \) since \( v_0^2 \sin(2\theta) \) remains the same.
03

Substitute Known Values

We know \( R_E = 32 \) m, \( R_M = 180 \) m, and the acceleration due to gravity on Earth \( g_E = 9.81 \) m/s². Substituting these into the equation \( \frac{32}{180} = \frac{9.81}{g_M} \).
04

Solve for Lunar Gravity

Cross-multiply to solve for \( g_M \): \( g_M = \frac{180 \times 9.81}{32} \). Calculating this gives \( g_M \approx 1.74 \) m/s².

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Acceleration due to gravity
Acceleration due to gravity, denoted as \( g \), is a crucial factor when it comes to understanding projectile motion. On Earth, this value is approximately 9.81 m/s². It represents the rate at which objects accelerate towards the ground, influencing how far and how high they can travel when launched.

In the context of the projectile motion exercise, the acceleration due to gravity affects the projectile's range. The initial velocity and launch angle are constants in this scenario, so variations in \( g \) directly influence the distance a projectile can cover. Understanding this concept helps solve problems related to projectile motion, especially when comparing different planetary bodies, like the Earth and the Moon.
Moon gravity
On the Moon, gravity plays a significantly different role compared to Earth. With gravitational acceleration on the Moon standing at approximately 1.74 m/s², it is roughly 1/6th of Earth's gravity.

This lower gravity means that a projectile, like a golf ball, would travel much farther as seen in the exercise. The range of motion is extended due to less gravitational pull, causing the trajectory to be more stretched. For example, where a golf ball might travel only 32 meters on Earth, it could reach 180 meters on the Moon, given the same initial conditions such as velocity and launch angle.

Understanding Moon gravity is essential for predicting how objects behave when launched on its surface, and highlights the impact of gravitational differences in projectile motion.
Kinematics
Kinematics refers to the study of motion without considering the forces that cause it. It involves understanding various aspects of motion such as velocity, acceleration, and time. In the projectile motion scenario, kinematics helps describe how an object moves through space over time.

Two primary components in kinematics are the horizontal and vertical motions of a projectile. While the horizontal motion involves constant velocity, the vertical motion is influenced by gravity. Together, these factors determine the flight path or trajectory of a projectile.

In our exercise, kinematics is used to derive the formula for the range of a projectile which relates distance, launch velocity, and gravitational acceleration. Understanding this interplay is essential for solving real-world projectile motion problems, especially in different gravitational fields, such as on Earth versus the Moon.
Range of projectile
The range of a projectile is the horizontal distance it travels during its flight. The range is influenced by several factors, including initial velocity, launch angle, and gravity. The equation for the range of a projectile is given by \( R = \frac{v_0^2 \sin(2\theta)}{g} \), where \( v_0 \) is the initial velocity, \( \theta \) is the launch angle, and \( g \) is the acceleration due to gravity.

In our exercise, this equation helps compare how far a golf ball can travel on Earth versus the Moon. The reduced gravity on the Moon means that the range of the golf ball is significantly increased, as evidenced by the ball traveling about 180 meters on the Moon compared to 32 meters on Earth.

Understanding the factors affecting the range of a projectile is essential for practical applications like sports, engineering, and space exploration. It's also a fundamental concept in physics that illustrates how different environments impact motion.

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Most popular questions from this chapter

A batter hits a fly ball which leaves the bat 0.90 m above the ground at an angle of 61\(^\circ\) with an initial speed of 28 m/s heading toward centerfield. Ignore air resistance. (\(a\)) How far from home plate would the ball land if not caught? (\(b\)) The ball is caught by the centerfielder who, starting at a distance of 105 m from home plate just as the ball was hit, runs straight toward home plate at a constant speed and makes the catch at ground level. Find his speed.

(II) A rescue plane wants to drop supplies to isolated mountain climbers on a rocky ridge 235 m below. If the plane is traveling horizontally with a speed of 250 km/h (69.4 m/s), how far in advance of the recipients (horizontal distance) must the goods be dropped (Fig. 3-38)?

(II) A passenger on a boat moving at 1.70 m/s on a still lake walks up a flight of stairs at a speed of 0.60 m/s, Fig. 3-43. The stairs are angled at 45\(^\circ\) pointing in the direction of motion as shown. What is the velocity of the passenger relative to the water?

(II) A grasshopper hops along a level road. On each hop, the grasshopper launches itself at angle \(\theta_0 =\) 45\(^\circ\) and achieves a range \(R =\) 0.80 m. What is the average horizontal speed of the grasshopper as it hops along the road? Assume that the time spent on the ground between hops is negligible.

(II) Two planes approach each other head-on. Each has a speed of 780 km/h, and they spot each other when they are initially 10.0 km apart. How much time do the pilots have to take evasive action?

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