Chapter 3: Problem 7
Is a projectile's speed constant throughout its parabolic trajectory?
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Chapter 3: Problem 7
Is a projectile's speed constant throughout its parabolic trajectory?
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An object undergoes acceleration \(2.3 \hat{\imath}+3.6 \hat{\jmath} \mathrm{m} / \mathrm{s}^{2}\) for \(10 \mathrm{s}\). At the end of this time, its velocity is \(33 \hat{\imath}+15 \hat{\jmath} \mathrm{m} / \mathrm{s} .\) (a) What was its velocity at the beginning of the 10 -s interval? (b) By how much did its speed change? (c) By how much did its direction change? (d) Show that the speed change is not given by the magnitude of the acceleration multiplied by the time. Why not?
You wish to row straight across a 63 -m-wide river. You can row at a steady \(1.3 \mathrm{m} / \mathrm{s}\) relative to the water, and the river flows at \(0.57 \mathrm{m} / \mathrm{s} .\) (a) What direction should you head? (b) How long will it take you to cross the river?
A kid fires a squirt gun horizontally from \(1.6 \mathrm{m}\) above the ground. It hits another kid \(2.1 \mathrm{m}\) away square in the back, \(0.93 \mathrm{m}\) above the ground. What was the water's initial speed?
Is there any point on a projectile's trajectory where velocity and acceleration are perpendicular?
The table below lists position versus time for an object moving in the \(x-y\) plane, which is horizontal in this case. Make a plot of position \(y\) versus \(x\) to determine the nature of the object's path. Then determine the magnitudes of the object's velocity and acceleration. $$\begin{array}{ccc} \text { Time, } t(\mathrm{s}) & x(\mathrm{m}) & y(\mathrm{m}) \\ 0 & 0 & 0 \\ 0.10 & 0.65 & 0.09 \\ 0.20 & 1.25 & 0.33 \\ 0.30 & 1.77 & 0.73 \\ 0.40 & 2.17 & 1.25 \\ 0.50 & 2.41 & 1.85 \\ 0.60 & 2.50 & 2.50 \end{array}$$ $$\begin{array}{ccc} \text { Time, } t(\mathrm{s}) & x(\mathrm{m}) & y(\mathrm{m}) \\ 0.70 & 2.41 & 3.15 \\ 0.80 & 2.17 & 3.75 \\ 0.90 & 1.77 & 4.27 \\ 1.00 & 1.25 & 4.67 \\ 1.10 & 0.65 & 4.91 \\ 1.20 & 0.00 & 5.00 \end{array}$$
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