Chapter 7: Problem 83
An arrow is shot into the air at an angle of \(37^{\circ}\) with an initial velocity of \(100 \mathrm{ft} / \mathrm{sec}\). Compute the horizontal and vertical components of the representative vector.
Short Answer
Expert verified
Horizontal: 79.86 ft/sec, Vertical: 60.18 ft/sec.
Step by step solution
01
Identify the Given Information
We are given that the arrow is shot at an initial velocity of \( v = 100 \) ft/sec and at an angle of \( \theta = 37^{\circ} \) from the horizontal. From this, we aim to find the horizontal and vertical components of the velocity.
02
Understand the Component Formulas
The formulas to resolve a vector into its components are: \[v_x = v \cdot \cos(\theta)\quad \text{and}\quad v_y = v \cdot \sin(\theta)\] where \( v_x \) is the horizontal component and \( v_y \) is the vertical component.
03
Calculate the Horizontal Component
Substitute the given values into the formula for the horizontal component: \[v_x = 100 \cdot \cos(37^{\circ})\] We need to use the cosine of \(37^{\circ}\), which is approximately \(0.7986\). Thus, \[v_x = 100 \cdot 0.7986 = 79.86 \text{ ft/sec}\]
04
Calculate the Vertical Component
Substitute the given values into the formula for the vertical component: \[v_y = 100 \cdot \sin(37^{\circ})\] We need to use the sine of \(37^{\circ}\), which is approximately \(0.6018\). Thus, \[v_y = 100 \cdot 0.6018 = 60.18 \text{ ft/sec}\]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Horizontal Component
To understand the horizontal component of a vector, think about what happens when you move across the ground, parallel to the horizon. This is what we call the horizontal direction. In the context of a projectile like an arrow, the horizontal component measures how far it moves left or right.
When resolving a vector into components, the horizontal component can be calculated using trigonometric functions. Specifically, the horizontal component, denoted here as \(v_x\), is calculated using the cosine function:
When resolving a vector into components, the horizontal component can be calculated using trigonometric functions. Specifically, the horizontal component, denoted here as \(v_x\), is calculated using the cosine function:
- The formula is \(v_x = v \cdot \cos(\theta)\), where \(v\) is the magnitude of the vector, and \(\theta\) is the angle the vector makes with the horizontal.
- In the given exercise, \(v = 100\) ft/sec and \(\theta = 37^{\circ}\).
- Substituting these values in, we get \(v_x = 100 \cdot \cos(37^{\circ})\).
- Using the approximate value of \(\cos(37^{\circ}) = 0.7986\), the horizontal component \(v_x\) becomes \(79.86\) ft/sec.
Vertical Component
Now, let's dive into the vertical component, which represents how high or low an object moves. Just like the horizontal component, we calculate the vertical part of a vector using trigonometric methods.
Think of it like watching a ball go up into the sky or fall back to the ground. That's all captured by the vertical component. For this, we often use the sine function:
Think of it like watching a ball go up into the sky or fall back to the ground. That's all captured by the vertical component. For this, we often use the sine function:
- For a vector making an angle \(\theta\) with the horizontal, the vertical component \(v_y\) is found using the formula \(v_y = v \cdot \sin(\theta)\).
- In our case, the initial speed \(v\) is 100 ft/sec, and the angle \(\theta\) is \(37^{\circ}\).
- We substitute these into the formula to get \(v_y = 100 \cdot \sin(37^{\circ})\).
- The approximate value of \(\sin(37^{\circ}) = 0.6018\), so \(v_y\) becomes \(60.18\) ft/sec.
Trigonometric Functions
Trigonometric functions, especially sine and cosine, are crucial in decomposing vectors. These functions allow us to translate the direction and magnitude of a vector into easily understandable horizontal and vertical movements.
Here’s why these functions are essential:
Here’s why these functions are essential:
- Cosine Function: Used to find the horizontal component. It relates the angle \(\theta\) with the ratio of the adjacent side to the hypotenuse in a right triangle. So, \(\cos(\theta)\) helps in estimating how much of the vector is directed horizontally.
- Sine Function: Used for the vertical component. It describes the angle \(\theta\) in terms of the ratio of the opposite side to the hypotenuse, making it ideal for determining vertical direction.
- Using these functions helps in breaking down any vector into components that are easier to work with and understand.
- This is quite useful in physics to predict the behavior of moving objects, like finding out how high or how far it will go given an initial speed and angle.