/*! 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 46 A \(2.0 \mathrm{kg}\) wood block... [FREE SOLUTION] | 91Ó°ÊÓ

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A \(2.0 \mathrm{kg}\) wood block is launched up a wooden ramp that is inclined at a \(30^{\circ}\) angle. The block's initial speed is \(10 \mathrm{m} / \mathrm{s}\) a. What vertical height does the block reach above its starting point? b. What speed does it have when it slides back down to its starting point?

Short Answer

Expert verified
a. The maximum vertical height the block reaches is approximately 5.1 m. b. The block has a speed of 10 m/s when it slides back down to its starting point.

Step by step solution

01

Determine the initial kinetic energy

The block starts with an initial speed, hence it possesses kinetic energy. The kinetic energy \( K.E \) of an object is given by \( \frac{1}{2} m v^2 \), where \( m \) is the mass and \( v \) is the speed. Given \( m = 2.0 \, \mathrm{kg} \) and \( v = 10 \, \mathrm{m/s} \), we find \( K.E = \frac{1}{2} \times 2.0 \, \mathrm{kg} \times (10 \, \mathrm{m/s})^2 = 100 \, \mathrm{J} \).
02

Determine the maximum height

The initial kinetic energy of the block equals the potential energy at its maximum height, because all the kinetic energy will be converted to potential energy. The potential energy \( P.E \) is given by \( m g h \), where \( h \) is the height, \( g \) is the acceleration due to gravity, and \( m \) is the mass of the object. Given \( m = 2.0 \, \mathrm{kg} \), \( P.E = 100 \, \mathrm{J} \), and \( g = 9.8 \, \mathrm{m/s^2} \), we find \( h = \frac{P.E}{m g} = \frac{100 \, \mathrm{J}}{2.0 \, \mathrm{kg} \times 9.8 \, \mathrm{m/s^{2}}} \approx 5.1 \, \mathrm{m} \).
03

Determine the final speed of the block

When the block slides back to its starting point, the potential energy at the maximum height is converted back to kinetic energy. According to the conservation of energy, the kinetic energy at the maximum height should equal the kinetic energy at the starting point, since no external forces are acting on the block. Hence, its final speed \( v \) is \( \sqrt{\frac{2 \times K.E}{m}} = \sqrt{\frac{2 \times 100 \, \mathrm{J}}{2.0 \, \mathrm{kg}}} = 10 \, \mathrm{m/s} \).

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Key Concepts

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

Kinetic Energy
Kinetic energy is the energy possessed by an object due to its motion. It's a form of energy that reflects the object's capacity to perform work as a result of its speed. This concept is crucial for understanding how objects move and interact in physics.

For example, the wood block in this problem has kinetic energy because it's moving up the inclined plane. To calculate this energy, we use the formula K.E = \( \frac{1}{2} m v^2 \), where m is the mass and v is the velocity of the object. The faster the object moves, or the more it weighs, the higher its kinetic energy will be. As the wood block ascends the ramp, its kinetic energy decreases until it reaches a point where this energy is completely transformed into potential energy.
Potential Energy
Potential energy is the energy stored within an object because of its position or configuration. Unlike kinetic energy, which is a function of an object’s movement, potential energy depends on its position relative to other objects.

In the case of our wood block, the potential energy is highest when the block reaches the maximum height on the inclined plane. This is due to its elevation in Earth’s gravitational field. The formula to calculate the gravitational potential energy is P.E = mgh, where m is the mass of the object, g is the acceleration due to gravity (approximately \(9.8 \text{m/s}^2\)), and h is the height above the starting point. This stored energy is what allows the block to potentially do work, such as sliding back down the ramp.
Conservation of Energy
The principle of conservation of energy is a fundamental concept in physics that states energy cannot be created or destroyed in an isolated system; it can only change forms. This principle is critical for solving many physics problems, including the motion of objects on an inclined plane.

In this exercise, when the wood block slides up the ramp, its kinetic energy is converted to potential energy. When it reaches the peak and starts descending, the process reverses: the potential energy is transformed back into kinetic energy. No energy is lost or gained in this process—the total energy of the block remains constant. This fact allows us to predict the final speed of the block when it slides back down to be equal to its initial speed, assuming no energy is lost to friction or other forces.
Inclined Plane
An inclined plane is a flat surface tilted at an angle, which forms a ramp. It is a simple machine that allows us to raise heavy objects using less force than would be needed to lift them vertically. The concept of an inclined plane helps us understand the components of gravitational force when an object is on a slope.

In the context of our problem, the inclined plane affects the conversion of kinetic energy to potential energy and vice versa. The angle of incline (\(30^{\text{\textdegree}}\) in this case) determines the rate at which the wood block loses its kinetic energy as it ascends and gains potential energy. When analyzing motions on an inclined plane, gravity is split into components parallel and perpendicular to the surface, changing the way an object accelerates down the slope.

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