Compressing the Ground A running track at Harvard University uses a surface with a force constant of 2.5 ×10°N/m This surface is compressed slightly every time a runner's foot lands on it. The force exerted by the foot, according to the Saucony shoe company, has a magnitude of 2700 N for a typical runner. Part A Treating the track's surface as an ideal spring, find the amount of compression caused by a foot hitting the track. Express your answer using two significant figures. cm Submit Request Answer Part B Treating the track's surface as an ideal spring, find the energy stored briefly in the track every time a foot lands. Express your answer using two significant figures. ν ΑΣφ ? U = J Submit Request Answer

Compressing the Ground A running track at Harvard University uses a surface with a force constant of 2.5 ×10°N/m This surface is compressed slightly every time a runner's foot lands on it. The force exerted by the foot, according to the Saucony shoe company, has a magnitude of 2700 N for a typical runner. Part A Treating the track's surface as an ideal spring, find the amount of compression caused by a foot hitting the track. Express your answer using two significant figures. cm Submit Request Answer Part B Treating the track's surface as an ideal spring, find the energy stored briefly in the track every time a foot lands. Express your answer using two significant figures. ν ΑΣφ ? U = J Submit Request Answer

Principles of Physics: A Calculus-Based Text

5th Edition

ISBN:9781133104261

Author:Raymond A. Serway, John W. Jewett

Publisher:Raymond A. Serway, John W. Jewett

Chapter8: Momentum And Collisions

Section: Chapter Questions

Problem 59P

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In a needle biopsy, a narrow strip of tissue is extracted from a patient with a hollow needle. Rather than being pushed by hand, to ensure a clean cut the needle can be fired into the patients body by a spring. Assume the needle has mass 5.60 g, the light spring has force constant 375 N/m, and the spring is originally compressed 8.10 cm to project the needle horizontally without friction. The tip of the needle then moves through 2.40 cm of skin and soft tissue, which exerts a resistive force of 7.60 N on it. Next, the needle cuts 3.50 cm into an organ, which exerts a backward force of 9.20 N on it. Find (a) the maximum speed of the needle and (b) the speed at which a flange on the back end of the needle runs into a stop, set to limit the penetration to 5.90 cm.
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A 75.0-kg firefighter slides down a pole while a constant friction force of 300 N retards her motion. A horizontal 20.0-kg platform is supported by a spring at the bottom of the pole to cushion the fall. The firefighter starts from rest 4.00 m above the platform, and the spring constant is 4 000 N/m. Find (a) the firefighters speed just before she collides with the platform and (b) the maximum distance the spring is compressed. Assume the friction force acts during the entire motion.
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