Chapter 11: Problem 52
Find the value of \(a\) such that \(\langle a, a, 2\rangle \times\langle 1, a, 3\rangle=\langle 2,-4,2\rangle\)
/*! 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}
Learning Materials
Features
Discover
Chapter 11: Problem 52
Find the value of \(a\) such that \(\langle a, a, 2\rangle \times\langle 1, a, 3\rangle=\langle 2,-4,2\rangle\)
All the tools & learning materials you need for study success - in one app.
Get started for free
Explain why or why not Determine whether the following statements are true and
give an explanation or counterexample.
a. The vectors \(\mathbf{r}(t)\) and \(\mathbf{r}^{\prime}(t)\) are parallel for
all values of \(t\) in the domain.
b. The curve described by the function \(\mathbf{r}(t)=\left\langle t, t^{2}-2
t, \cos \pi t\right\rangle\)
is smooth, for \(-\infty
Suppose \(\mathbf{u}\) and \(\mathbf{v}\) are vectors in the plane. a. Use the Triangle Rule for adding vectors to explain why \(|\mathbf{u}+\mathbf{v}| \leq|\mathbf{u}|+|\mathbf{v}| .\) This result is known as the Triangle Inequality. b. Under what conditions is \(|\mathbf{u}+\mathbf{v}|=|\mathbf{u}|+|\mathbf{v}| ?\)
Let \(\mathbf{u}=\langle a, 5\rangle\) and \(\mathbf{v}=\langle 2,6\rangle\) a. Find the value of \(a\) such that \(\mathbf{u}\) is parallel to \(\mathbf{v}\) b. Find the value of \(a\) such that \(\mathbf{u}\) is perpendicular to \(\mathbf{v}\)
Suppose water flows in a thin sheet over the \(x y\) -plane with a uniform velocity given by the vector \(\mathbf{v}=\langle 1,2\rangle ;\) this means that at all points of the plane, the velocity of the water has components \(1 \mathrm{m} / \mathrm{s}\) in the \(x\) -direction and \(2 \mathrm{m} / \mathrm{s}\) in the \(y\) -direction (see figure). Let \(C\) be an imaginary unit circle (that does not interfere with the flow). a. Show that at the point \((x, y)\) on the circle \(C\), the outwardpointing unit vector normal to \(C\) is \(\mathbf{n}=\langle x, y\rangle\) b. Show that at the point \((\cos \theta, \sin \theta)\) on the circle \(C,\) the outwardpointing unit vector normal to \(C\) is also \(\mathbf{n}=\langle\cos \theta, \sin \theta\rangle\) c. Find all points on \(C\) at which the velocity is normal to \(C\). d. Find all points on \(C\) at which the velocity is tangential to \(C\). e. At each point on \(C\), find the component of \(\mathbf{v}\) normal to \(C\). Express the answer as a function of \((x, y)\) and as a function of \(\theta\) f. What is the net flow through the circle? That is, does water accumulate inside the circle?
Proof of Product Rule By expressing \(\mathbf{u}\) in terms of its components, prove that $$\frac{d}{d t}(f(t) \mathbf{u}(t))=f^{\prime}(t) \mathbf{u}(t)+f(t) \mathbf{u}^{\prime}(t)$$
What do you think about this solution?
We value your feedback to improve our textbook solutions.