/*! 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 79 A student is skateboarding down ... [FREE SOLUTION] | 91Ó°ÊÓ

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A student is skateboarding down a ramp that is \(6.0 \mathrm{m}\) long and inclined at \(18^{\circ}\) with respect to the horizontal. The initial speed of the skateboarder at the top of the ramp is \(2.6 \mathrm{m} / \mathrm{s}\). Neglect friction and find the speed at the bottom of the ramp.

Short Answer

Expert verified
The speed at the bottom of the ramp is approximately \(6.76 \text{ m/s}\).

Step by step solution

01

Identify given values

The length of the ramp is given as \(6.0 \text{ m}\), the incline angle is \(18^\circ\), and the initial speed of the skateboarder at the top is \(2.6 \text{ m/s}\). We need to find the speed at the bottom of the ramp while neglecting friction.
02

Using energy conservation

Since there is no friction, we can use the conservation of mechanical energy to solve this. The mechanical energy at the top (potential energy + initial kinetic energy) will equal the kinetic energy at the bottom (as potential energy will be zero at the bottom).
03

Calculate potential energy at the top

The height \(h\) of the ramp can be determined using trigonometry: \(h = L \sin \theta = 6.0 \times \sin 18^\circ\). Then, the potential energy \(PE\) at the top is \(mgh\), where \(g = 9.8 \text{ m/s}^2\).
04

Calculate initial kinetic energy

The initial kinetic energy \(KE_i\) at the top is given by the formula \(\frac{1}{2}mv_i^2\), where \(v_i = 2.6 \text{ m/s}\).
05

Setup and solve energy balance equation

At the bottom of the ramp, all the potential energy is converted into kinetic energy. So, the energy conservation equation is: \( KE_i + PE = KE_f \). Substitute the expressions for \(PE\) and initial kinetic energy to solve for the final velocity \(v_f\).
06

Simplify to find final velocity

Solving the equation \( \frac{1}{2}mv_i^2 + mgh = \frac{1}{2}mv_f^2 \), gives \(v_f = \sqrt{v_i^2 + 2gh}\). Now substitute \(v_i = 2.6 \text{ m/s}\), \(g = 9.8 \text{ m/s}^2\), and \(h\) calculated in Step 3 to find \(v_f\).

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Key Concepts

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

Energy Conservation
Energy conservation is a vital concept in physics. It states that energy cannot be created or destroyed, only transformed from one form to another. In this skateboard problem, the principle of energy conservation helps simplify our calculations. Here, the total mechanical energy of the skateboarder is conserved. This means the energy at the start (top of the ramp) will equal the energy at the end (bottom of the ramp).
At the top of the ramp, the skateboarder has both potential energy from being elevated and kinetic energy from their speed. As they move down, the potential energy converts to kinetic energy. The total energy remains constant, simplifying the problem to just focusing on changes between kinetic and potential energy. This method allows for solving without knowing specific forces, like friction, by balancing energy at two points.
Using energy conservation is a common strategy in physics as it often makes complex problems much simpler and more intuitive.
Kinetic Energy
Kinetic energy is the energy of motion. Its formula is given by \( \frac{1}{2}mv^2 \), where \(m\) is the mass and \(v\) is the velocity. In the exercise, the skateboarder starts with a certain kinetic energy at the top of the ramp due to their initial speed. Throughout the descent, changes in kinetic energy help us find the final speed at the ramp’s bottom.
Understanding kinetic energy is crucial when solving motion problems. The key is to relate it to other forms of energy, like potential energy, which this exercise clearly illustrates. As potential energy decreases, kinetic energy increases and vice versa, keeping the total mechanical energy constant. This understanding transforms the complex motion down the ramp into a straightforward calculation using energy conservation.
In energy terms, the skateboarder goes faster due to increased kinetic energy gained from released potential energy throughout the descent.
Potential Energy
Potential energy, dictated by position or height, is a critical concept here. It is defined as \(mgh\), where \(m\) is mass, \(g\) is gravity, and \(h\) is height. At the ramp's top, the skateboarder has maximum potential energy since they start at the highest point.
As the skateboarder moves down, potential energy turns into kinetic energy. Calculating potential energy requires determining the height the skateboarder moves through, which can be found using trigonometry. This interchange between potential and kinetic energy allows us to easily find speed changes by considering energy shifts.
Grasping the concept of potential energy helps simplify the physics of motion. It allows us to use height and position calculations to understand how energy transforms throughout the skateboarder's journey. This exercise shows how energy states change through motion and height differences.
Trigonometry in Physics
Trigonometry is invaluable in solving physics problems where angles and inclines are involved. In this exercise, it helps determine the vertical height of the ramp using the formula: \(h = L \sin \theta\). Here, \(L\) is the length of the ramp, and \(\theta\) is the incline angle.
Understanding the basics of trigonometry allows us to break down sloped movements into horizontal and vertical components, crucial for physics. In real-life physics problems, vectors and angles dictate many results, so mastering these relations using trigonometric identities is important.
Utilizing trigonometry in this exercise helps ascertain initial conditions necessary for calculating potential energy. By knowing how to work with angles and lengths, we transform complex motion down a ramp into manageable calculations by finding height and applying it to energy principles. This link between angles and distances is essential in translating real-world motion into mathematical expressions in physics.

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Most popular questions from this chapter

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