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Consult Multiple-Concept Example 10 for insight into solving this type of problem. A box is sliding up an incline that makes an angle of \(15.0^{\circ}\) with respect to the horizontal. The coefficient of kinetic friction between the box and the surface of the incline is \(0.180 .\) The initial speed of the box at the bottom of the incline is \(1.50 \mathrm{~m} / \mathrm{s}\). How far does the box travel along the incline before coming to rest?

Short Answer

Expert verified
The box travels approximately 0.364 meters up the incline before coming to rest.

Step by step solution

01

Analyze Forces on the Box

Consider the forces acting on the box as it moves up the incline. The forces include the gravitational force, the normal force, and the frictional force. The gravitational force has a component parallel to the incline, given by \( mg \sin \theta \), and a component perpendicular to the incline, given by \( mg \cos \theta \). The frictional force, which opposes the motion, is \( \mu_k \times \text{Normal force} = \mu_k mg \cos \theta \).
02

Write the Equation of Motion

According to Newton's second law, the net force equals mass times acceleration. As the box is sliding up the incline, the net force is given by \( -mg \sin \theta - \mu_k mg \cos \theta = ma \), where \( a \) is the acceleration of the box. Simplifying for \( a \), we have \( a = -g \sin \theta - \mu_k g \cos \theta \).
03

Calculate the Acceleration

Substitute the given values into the acceleration equation: \( g = 9.81 \text{ m/s}^2\), \( \theta = 15.0^\circ \), \( \mu_k = 0.180 \). The acceleration is \( a = -9.81 (\sin 15.0^\circ + 0.180 \cos 15.0^\circ) \). Calculate this to find \( a \approx -3.09 \text{ m/s}^2 \).
04

Use Kinematic Equation to Find Distance

Use the equation \( v^2 = u^2 + 2as \) to find the distance \( s \) that the box travels. Here, \( v = 0 \) m/s (the final velocity), \( u = 1.50 \) m/s (the initial velocity), and \( a = -3.09 \) m/s². Solving for \( s \), we have \( 0 = (1.50)^2 + 2(-3.09)s \). Rearrange to solve for \( s \): \( s = \frac{(1.50)^2}{2 \times 3.09} \).
05

Calculate the Distance

Compute the value of \( s \) using the values from the previous step: \( s = \frac{2.25}{6.18} \). Thus, \( s \approx 0.364 \text{ m} \).

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Key Concepts

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

Newton's second law
Understanding Newton's second law is key to solving problems involving motion, such as a box sliding up an inclined plane. Newton's second law states that the net force acting on an object is equal to the mass of the object multiplied by its acceleration, represented by the equation:
  • \( F_{net} = ma \)
In the context of an object moving up an inclined plane, several forces come into play:
  • The gravitational force, which pulls the object downwards.
  • The normal force, which is perpendicular to the surface of the incline.
  • The kinetic frictional force, which opposes the motion of the object up the incline.
When these forces are added together as vectors, they result in a net force that determines the acceleration of the object according to Newton's laws.
This translates to the formula for our scenario:
  • \( -mg \sin \theta - \mu_k mg \cos \theta = ma \)
Here, \( mg \sin \theta \) is the component of gravity pulling the box down the slope, and \( \mu_k mg \cos \theta \) is the frictional force acting in the opposite direction of the box's motion. Understanding how to apply Newton's second law in these circumstances allows us to solve for the box's acceleration.
Inclined plane
An inclined plane is one of the classic simple machines and plays a huge role in physics problems. It is essentially a flat surface tilted at an angle to the horizontal, and this angle impacts how forces act on an object placed on it.When an object is on an inclined plane:
  • The gravitational force acting on it can be split into two components: one parallel to the incline and one perpendicular to it.
  • The parallel component is responsible for accelerating the object down the ramp, calculated as \( mg \sin \theta \).
  • The perpendicular component, \( mg \cos \theta \), affects the normal force, which is crucial for calculating frictional forces.
The inclined plane amplifies the effects of friction. The frictional force, given by the formula \( \mu_k \times \text{Normal force} = \mu_k mg \cos \theta \), resists motion and depends on both the angle of the incline and coefficients of friction.
Understanding these components helps explain why objects accelerate differently depending on the incline angle, even without changing surface roughness.
Kinematic equations
Kinematic equations are essential tools for solving motion problems where acceleration is constant. These equations allow us to link variables such as displacement, initial velocity, final velocity, time, and acceleration.The equation used in the step-by-step solution is one of the most common forms:
  • \( v^2 = u^2 + 2as \)
Where:
  • \( v \) is the final velocity.
  • \( u \) is the initial velocity.
  • \( a \) is the acceleration.
  • \( s \) is the displacement or distance traveled.
In the context of our problem, this equation is used to find how far the box travels before coming to rest. By rearranging the equation, we can solve for \( s \), using known values for initial velocity (\( u = 1.50 \) m/s), final velocity (\( v = 0 \) m/s as the box stops), and acceleration (\( a = -3.09 \) m/s²).
This ultimately helps in determining the distance \( s \) the box covers while being influenced by constant acceleration on the inclined plane.

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Most popular questions from this chapter

A block whose weight is \(45.0 \mathrm{~N}\) rests on a horizontal table. A horizontal force of \(36.0 \mathrm{~N}\) is applied to the block. The coefficients of static and kinetic friction are 0.650 and 0.420 , respectively. Will the block move under the influence of the force, and, if so, what will be the block's acceleration? Explain your reasoning.

A 350 -kg sailboat has an acceleration of \(0.62 \mathrm{~m} / \mathrm{s}^{2}\) at an angle of \(64^{\circ}\) north of east. Finc the magnitude and direction of the net force that acts on the sailboat.

A cable is lifting a construction worker and a crate, as the drawing shows. The weights of the worker and crate are 965 and \(1510 \mathrm{~N}\), respectively. The acceleration of the cable is \(0.620 \mathrm{~m} / \mathrm{s}^{2},\) upward. What is the tension in the cable (a) below the worker and (b) above the worker?

Several people are riding in a hot-air balloon. The combined mass of the people and balloon is \(310 \mathrm{~kg} .\) The balloon is motionless in the air, because the downward-acting weight of the people and balloon is balanced by an upward-acting "buoyant" force. If the buoyant force remains constant, how much mass should be dropped overboard so the balloon acquires an upward acceleration of \(0.15 \mathrm{~m} / \mathrm{s}^{2} ?\)

The principles used to solve this problem are similar to those in Multiple- Concept Example 17 . A \(205-\mathrm{kg}\) log is pulled up a ramp by means of a rope that is parallel to the surface of the ramp. The ramp is inclined at \(30.0^{\circ}\) with respect to the horizontal. The coefficient of kinetic friction between the log and the ramp is \(0.900,\) and the log has an acceleration of \(0.800 \mathrm{~m} / \mathrm{s}^{2}\). Find the tension in the rope.

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