Chapter 10: Problem 19
Find the principal unit normal vector to the curve at the specified value of the parameter. $$ \mathbf{r}(t)=\ln t \mathbf{i}+(t+1) \mathbf{j}, \quad t=2 $$
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Chapter 10: Problem 19
Find the principal unit normal vector to the curve at the specified value of the parameter. $$ \mathbf{r}(t)=\ln t \mathbf{i}+(t+1) \mathbf{j}, \quad t=2 $$
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Prove the property. In each case, assume that \(\mathbf{r}, \mathbf{u},\) and \(\mathbf{v}\) are differentiable vector-valued functions of \(t,\) \(f\) is a differentiable real-valued function of \(t,\) and \(c\) is a scalar. $$ D_{t}[\mathbf{r}(f(t))]=\mathbf{r}^{\prime}(f(t)) f^{\prime}(t) $$
In Exercises 41 and \(42,\) use the definition of the derivative to find \(\mathbf{r}^{\prime}(t)\). $$ \mathbf{r}(t)=(3 t+2) \mathbf{i}+\left(1-t^{2}\right) \mathbf{j} $$
Use the model for projectile motion, assuming there is no air resistance. A projectile is fired from ground level at an angle of \(12^{\circ}\) with the horizontal. The projectile is to have a range of 150 feet. Find the minimum initial velocity necessary.
Find \(\mathbf{r}(t)\) for the given conditions. $$ \mathbf{r}^{\prime}(t)=\frac{1}{1+t^{2}} \mathbf{i}+\frac{1}{t^{2}} \mathbf{j}+\frac{1}{t} \mathbf{k}, \quad \mathbf{r}(1)=2 \mathbf{i} $$
Use the model for projectile motion, assuming there is no air resistance. Use a graphing utility to graph the paths of a projectile for the given values of \(\theta\) and \(v_{0} .\) For each case, use the graph to approximate the maximum height and range of the projectile. (Assume that the projectile is launched from ground level.) (a) \(\theta=10^{\circ}, v_{0}=66 \mathrm{ft} / \mathrm{sec}\) (b) \(\theta=10^{\circ}, v_{0}=146 \mathrm{ft} / \mathrm{sec}\) (c) \(\theta=45^{\circ}, v_{0}=66 \mathrm{ft} / \mathrm{sec}\) (d) \(\theta=45^{\circ}, v_{0}=146 \mathrm{ft} / \mathrm{sec}\) (e) \(\theta=60^{\circ}, v_{0}=66 \mathrm{ft} / \mathrm{sec}\) (f) \(\theta=60^{\circ}, v_{0}=146 \mathrm{ft} / \mathrm{sec}\)
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