Chapter 2: Problem 28
You're driving at \(70 \mathrm{km} / \mathrm{h}\) when you apply constant acceleration to pass another car. Six seconds later, you're doing \(80 \mathrm{km} / \mathrm{h}\). How far did you go in this time?
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Chapter 2: Problem 28
You're driving at \(70 \mathrm{km} / \mathrm{h}\) when you apply constant acceleration to pass another car. Six seconds later, you're doing \(80 \mathrm{km} / \mathrm{h}\). How far did you go in this time?
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A base runner can get from first to second base in 3.4 s. If he leaves first as the pitcher throws a 90 mi/h fastball the 61 -ft distance to the catcher, and if the catcher takes 0.45 s to catch and rethrow the ball, how fast does the catcher have to throw the ball to second base to make an out? Home plate to second base is the diagonal of a square 90 ft on a side.
A balloon is rising at \(10 \mathrm{m} / \mathrm{s}\) when its passenger throws a ball straight up at \(12 \mathrm{m} / \mathrm{s}\) relative to the balloon. How much later does the passenger catch the ball?
The standard 26-mile, 385-yard marathon dates to 1908, when the Olympic marathon started at Windsor Castle and finished before the Royal Box at London's Olympic Stadium. Today's top marathoners achieve times around 2 hours, 3 minutes for the standard marathon. (a) What's the average speed of a marathon run in this time? (b) Marathons before 1908 were typically about 25 miles. How much longer does the race last today as a result of the extra mile and 385 yards, assuming it's run at part (a)'s average speed?
An object's acceleration is given by the expression \(a(t)=-a_{0} \cos \omega t,\) where \(a_{0}\) and \(\omega\) are positive constants. Find expressions for the object's (a) velocity and (b) position as functions of time. Assume that at time \(t=0\) it starts from rest at its greatest positive displacement from the origin. (c) Determine the magnitudes of the object's maximum velocity and maximum displacement from the origin.
You're speeding at \(85 \mathrm{km} / \mathrm{h}\) when you notice that you're only 10 m behind the car in front of you, which is moving at the legal speed limit of \(60 \mathrm{km} / \mathrm{h}\). You slam on your brakes, and your car negatively accelerates at \(4.2 \mathrm{m} / \mathrm{s}^{2}\). Assuming the other car continues at constant speed, will you collide? If so, at what relative speed? If not, what will be the distance between the cars at their closest approach?
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