13.3: Chapter 13 Homework Problems
Exercise \(\PageIndex{1}\)
An impact-testing device consists of a 20-kilogram box supported by two slender 5-kilogram rods. The two rods are set up in parallel so that the box remains level as it swings. If the whole system is released from the horizontal position shown below, what is the velocity of the box after it has traveled 90°?
- Solution
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\(v = 3.97 \ m/s\)
Example \(\PageIndex{2}\)
A 40-lb door with a width of 36 inches is attached to a spring with an unstretched length of 4 inches, designed to close the door when left open. The spring is anchored as shown below when closed (solid outline is closed, dotted outline is open 90°). If we want the door to have an angular velocity of 0.2 rad/s upon closing when released from rest at the 90° open position, what should the spring constant of the spring be? (This is the top view of the door below)
- Solution
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\(k = 2.68 \ lb/ft = 0.224 \ lb/in.\)