Edition 2 (Edition 1)

6.15 (6.16)

6.24 (new)
Spider silk is a remarkable elastic material. A particular strand has spring constant 70 mN/m, and it stretches 9.5 cm when a fly hits it. How much work did the fly's impact do on the silk strand?

6.27 (6.28)

6.31(6.33)

6.36 (6.38)

6.43
You're at the gym, doing arm raises. With each rep, you lift a 18 N weight 56 cm. How many raises must you do before you've expended 200 kcal of work? If your workout takes 6.0 min, what's your average power output?

6.61 (6.62)

6.71 (6.70)

6.81 (6.81)

7.10 (7.11)

7.15 (7.17)

7.21 (7.22)

7.28 (7.29)

7.34
For small stretches, the Achilles tendon can be modeled as an ideal spring. Experiments using a particular tendon showed that it stretched 2.66 mm when a 125-kg mass was hung from it. Find the spring constant of this tendon. How much would it have to stretch to store 50.0 J of energy?

7.38 (7.39)

7.52 (7.54)

7.62 (7.64)

7.64 (7.66)

7.66 (7.69)

8.17 (8.18)

8.23
The Mars Reconnaissance Orbiter circles the red planet with a 116 min period. What's the spacecraft's altitude?

8.25 (8.26)

8.35 (8.35)

8.40 (8.39)

8.46 (8.43)

8.51
You're in charge of tracking celestial objects that might pose a danger to Earth. Astronomers have discovered a new comet that's moving at 45 km/s as it crosses Earth's orbit. Determine whether the comet will again return to Earth's vicinity.

8.65 (8.62)