Skip to main content
Ch 03: Vectors and Coordinate Systems
Knight Calc - Physics for Scientists and Engineers 5th Edition
Knight Calc5th EditionPhysics for Scientists and EngineersISBN: 9780137344796Not the one you use?Change textbook
Chapter 3, Problem 35a

Jack and Jill ran up the hill at 3.0 m/s. The horizontal component of Jill's velocity vector was 2.5 m/s. What was the angle of the hill?

Verified step by step guidance
1
Identify the components of Jill's velocity vector. The horizontal component is given as 2.5 m/s, and the total velocity is 3.0 m/s. The angle of the hill can be determined using trigonometric relationships.
Recall the trigonometric definition of cosine: \( \cos(\theta) = \frac{\text{adjacent}}{\text{hypotenuse}} \). Here, the adjacent side corresponds to the horizontal component of Jill's velocity (2.5 m/s), and the hypotenuse corresponds to the total velocity (3.0 m/s).
Rearrange the formula to solve for the angle \( \theta \): \( \theta = \cos^{-1}\left(\frac{\text{horizontal component}}{\text{total velocity}}\right) \).
Substitute the given values into the equation: \( \theta = \cos^{-1}\left(\frac{2.5}{3.0}\right) \).
Use a calculator or mathematical software to compute the inverse cosine of the ratio. This will give you the angle of the hill in degrees or radians, depending on the context.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
4m
Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Velocity Components

Velocity can be broken down into horizontal and vertical components. In this scenario, Jill's velocity vector has a horizontal component of 2.5 m/s, which is part of her overall velocity. Understanding how to resolve a vector into its components is crucial for analyzing motion on inclined surfaces.
Recommended video:
Guided course
05:53
Calculating Velocity Components

Trigonometric Functions

Trigonometric functions, particularly sine and cosine, are essential for relating the angles of a triangle to the ratios of its sides. In this case, the angle of the hill can be determined using the tangent function, which relates the vertical rise to the horizontal run. This relationship is fundamental in physics for analyzing inclined planes.
Recommended video:
Guided course
08:30
Intro to Wave Functions

Inclined Plane Dynamics

Inclined planes are surfaces that are tilted at an angle to the horizontal. The dynamics of objects on inclined planes involve gravitational forces, normal forces, and friction. Understanding how these forces interact helps in calculating the angle of the incline based on the components of motion, such as velocity.
Recommended video:
Guided course
06:59
Intro to Inclined Planes