Math Problem Statement

A radio-controlled model airplane has a momentum given by [(−0.75 kg·m/s³)t² + (3.0 kg·m/s)]î + (0.25 kg·m/s²)tĵ. What are the x-, y-, and z-components of the net force on the airplane?

Solution

To solve this problem, we need to find the components of the net force on the airplane from the given momentum equation.

Given:

Momentum p(t)\vec{p}(t) is provided as: p(t)=(0.75kgm/s3)t2i^+(3.0kgm/s)i^+(0.25kgm/s2)tj^\vec{p}(t) = \left( -0.75 \, \text{kg} \cdot \text{m/s}^3 \right)t^2 \hat{i} + \left( 3.0 \, \text{kg} \cdot \text{m/s} \right) \hat{i} + \left( 0.25 \, \text{kg} \cdot \text{m/s}^2 \right)t \hat{j}

Unknown:

The net force F(t)\vec{F}(t), which has x-, y-, and z-components (if applicable).

Equation:

Force is related to momentum by the equation: F(t)=dp(t)dt\vec{F}(t) = \frac{d\vec{p}(t)}{dt} Thus, we can find the net force by differentiating the momentum equation with respect to time.

Solution:

Let's differentiate each term of the momentum function:

  1. For the i^\hat{i} (x-component) term: = -0.75 \cdot 2t \, \text{kg} \cdot \text{m/s}^3 = -1.5t \, \text{N}$$ The constant term $$3.0 \, \text{kg} \cdot \text{m/s}$$ disappears since the derivative of a constant is zero.
  2. For the j^\hat{j} (y-component) term: ddt(0.25kgm/s2t)=0.25kgm/s2=0.25N\frac{d}{dt}\left( 0.25 \, \text{kg} \cdot \text{m/s}^2 \cdot t \right) = 0.25 \, \text{kg} \cdot \text{m/s}^2 = 0.25 \, \text{N}

Final Answer:

The net force F(t)\vec{F}(t) is: F(t)=(1.5t)i^+(0.25)j^\vec{F}(t) = (-1.5t) \hat{i} + (0.25) \hat{j}

Thus, the x-component of the net force is 1.5tN-1.5t \, \text{N}, the y-component is 0.25N0.25 \, \text{N}, and there is no z-component (since the momentum expression doesn't include any k^\hat{k}-terms).

Do you have any questions, or would you like more details on the differentiation process?

Related Questions:

  1. How does force relate to the rate of change of momentum in general?
  2. What would happen if the momentum had a zz-component in this problem?
  3. How can you determine the acceleration of the airplane using the force found?
  4. What physical meaning does the constant 3.0kgm/s3.0 \, \text{kg} \cdot \text{m/s} term have in the momentum equation?
  5. How would you interpret the units of the various terms in the momentum equation?

Tip: Always make sure the units of momentum are consistent (e.g., kg·m/s) before performing any operations on them.

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Math Problem Analysis

Mathematical Concepts

Calculus
Differentiation
Vector components

Formulas

Force = d(momentum)/dt

Theorems

Newton's Second Law of Motion

Suitable Grade Level

Grades 11-12, College Intro Physics