In attempting to pass the puck to a teammate, a hockey player gives it an initia

Question

In attempting to pass the puck to a teammate, a hockey player gives it an initial speed of 2.1 m/s. However, this speed is inadequate to compensate for the kinetic friction between the puck and the ice. As a result, the puck travels only one-half the reached between the players before sliding to a halt. What minimum initial speed should the puck have been given so that the teammate, assuming that the same force of kinetic friction acted on the puck everywhere between the two players? m/s points CJ106 Po63 My Notes o Ask Your Teacher Bicyclists in the Tour de France do enormous amounts of work race. p kilogram generated by seven-time-winner Lance Armstrong (m during a For example, the average power 75.0 kg) is 6.50 w per kilogram of his body mass (a) How much work does he do during a 140-km race in which his average speed is 12.0 m/s? (b) often, the work done is expressed in nutritional calories rather than in joules. Express the work done in part (a) in terms of nutritional Calories, noting that 1 joule 2.389 x 104 nutritional Calories nutritional Calories Submit Answer Save Progress

Explanation / Answer

1) 1/2 mv^2 = Friction force*d
1/2*m*2^2 = f*d and
1/2*m*v^2 = f*2d

2^2/v^2 = 1/2
v^2 = 2*2^2

v = sqrt(8) = 2.828 m/s

2) p = 6.5*75 = 487.5 W

time for the race is t = 140000/12 = 11666.7 sec

w = p*t = 5687500J

w = 5687500/4186 = 1358.7 cal

w = 5687500*2.389*10^-4 = 1358.7 nutritational calories

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.