/*! 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 36 A \(0.25 \mathrm{~kg}\) puck is ... [FREE SOLUTION] | 91Ó°ÊÓ

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A \(0.25 \mathrm{~kg}\) puck is initially stationary on an ice surface with negligible friction. At time \(t=0,\) a horizontal force begins to move the puck. The force is given by \(\vec{F}=\left(12.0-3.00 t^{2}\right) \mathrm{i},\) with \(\vec{F}\) in newtons and \(t\) in seconds, and it acts until its magnitude is zero. (a) What is the magnitude of the impulse on the puck from the force between \(t=0.500 \mathrm{~s}\) and \(t=1.25 \mathrm{~s} ?\) (b) What is the change in momentum of the puck between \(t=0\) and the instant at which \(F=0 ?\)

Short Answer

Expert verified
(a) Impulse is 7.171875 Ns. (b) Change in momentum is 16 kg·m/s.

Step by step solution

01

Understanding the Impulse Equation

Impulse is defined as the integral of force over a time interval. Mathematically, it is expressed as \( J = \int F(t) \, dt \), where \( F(t) \) is the force as a function of time.
02

Compute the Impulse (t=0.5s to t=1.25s)

Given \( F(t) = 12.0 - 3.00 t^2 \), the impulse from \( t = 0.5 \) s to \( t = 1.25 \) s is calculated as: \( J = \int_{0.5}^{1.25} (12.0 - 3.00 t^2) \, dt \). First, find the antiderivative: \( J = \left[ 12.0t - \frac{3.00}{3}t^3 \right]_{0.5}^{1.25} \).Calculate: \( J = (12.0 \times 1.25 - 1.00 \times 1.25^3) - (12.0 \times 0.5 - 1.00 \times 0.5^3) \). Evaluate the expressions: \( J = (15 - 1.953125) - (6 - 0.125) \).\( J = 15 - 1.953125 - 6 + 0.125 \) which results in \( J = 7.171875 \) Ns.
03

Determine When Force F(t) becomes Zero

The force given is \( F(t) = 12.0 - 3.00 t^2 \). Set this equal to zero to find when \( F(t) \) becomes zero: \( 12.0 - 3.00 t^2 = 0 \). Solve for \( t \): \( 3.00 t^2 = 12.0 \)\( t^2 = 4 \)\( t = 2 \) s.
04

Calculate Change in Momentum from t=0 to t=2s

Impulse is also equal to the change in momentum, \( \Delta p = J \). To find the change in momentum from \( t = 0 \) to \( t = 2 \) s, calculate: \( \Delta p = \int_{0}^{2} (12.0 - 3.00 t^2) \, dt \). Use a similar process as in Step 2: \( \Delta p = \left[ 12.0t - \frac{3.00}{3}t^3 \right]_{0}^{2} \).Evaluate at bounds: \( \Delta p = (12.0 \times 2 - 1.00 \times 2^3) \) which results in \( \Delta p = 24 - 8 \), giving \( \Delta p = 16 \) kg·m/s.

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Key Concepts

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

Calculus in Physics
In physics, calculus is a powerful tool that helps to understand and solve real-world problems involving changing quantities. It provides a way to quantify the relationships between physical variables.
For instance, in the problem about the puck, the force applied to it changes over time, which requires calculus to evaluate the overall effect on the puck. By integrating a function that describes the force over time, you determine the impulse on the puck.
  • Integration determines areas under curves, which in this context means the accumulated effect of the force over a specified interval.
  • The force function given as a polynomial, \(F(t) = 12.0 - 3.00 t^2\), can be integrated to calculate quantities like impulse.
Calculus allows precise calculations of these quantities, turning complex motion-related and force-related problems into solvable equations.
Newton's Laws of Motion
Newton's laws are fundamental to understanding motion in physics. Specifically, his second law of motion is relevant to the problem at hand.
  • This law states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. The relationship is given by \(F = ma\).
  • It implies that when a force is applied, objects will change their velocity over time, depending on their mass.
Applying Newton's second law clarifies how the force applied to the puck results in its acceleration and subsequent change in momentum.
This is the core mechanism behind calculating changes in motion, such as how impulses and forces affect velocities over time.
Force-Time Integral
The force-time integral is a vital concept in physics as it directly relates impulse and momentum. This integral helps you compute the impulse given a time-dependent force.
Impulse, defined as \(J = \int F(t) \, dt\), is the total change in momentum produced by the force over a time interval.
  • For the puck, the impulse was computed over intervals, showing how integrals represent the accumulated effects of force.
  • The integral is evaluated by finding the antiderivative and using bounds, essential for finding precise moments when forces have tangible impacts.
Through understanding this concept, you grasp that integration of force over time explains how gradual or time-varying applications of force lead to changes in motion and momentum.

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Most popular questions from this chapter

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