Unformatted text preview: s maximum compression is 16 em. The dght-hand spring has k = 280 N/m. Find (a) the maximum compression of the right-hand spring and (b) the speed of the block as it moves between the springs. Problem
27. Two clever kids use a huge spring with k = 890 N/m to launch their toboggan at the top of a 9.5-m-high hill (Fig. 8-28). The rhli.SS of kids plus toboggan is 80 kg. If the kids manage to compress the spring 2.6 m, (a) what will be their speed at the bottom of the hill? (b) What fraction of their final kinetic energy was initially stored in the spring? Neglect friction.
FIGURE 8-29 Problem 28. Solution
In the absence of friction and air resistance, the mechanical energy of the block is conserved. If the surface is horizontal (no change in Ugrav), then !kiX; = ~krx;, where Xi and Xr are the maximum compressions of the left-and right-hand springs, respectively (at which points the block is instantaneously at rest). Thus,xr = xty'kt./kr = (16 cm)y'130/280 ~ 10.9 em. (b) At some point Solution
If friction is neglected everywhere (in the spring, on the snow, through t...
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