At the beginning of a bobsled race, teammates push their bobsled along the track before jumping into it.

a. Before the teammates jump in, they push the bobsled (m = 150 kg) from rest to a speed of 4.2 m/s. How much kinetic energy does the bobsled gain?

b. How much work did the bobsled team do? Explain how you found the answer.

c. If the teammates pushed the bobsled with a force of 500 N, over what distance did they apply the force?

d. Later, the bobsled is racing down the track at a speed of 28 m/s. With the team in it, the bobsled has a total mass of 430 kg. How much work must be done by air resistance to slow down the bobsled to 25 m/s?

Question

Physics

Priscilla

22 July, 09:05

At the beginning of a bobsled race, teammates push their bobsled along the track before jumping into it.

a. Before the teammates jump in, they push the bobsled (m = 150 kg) from rest to a speed of 4.2 m/s. How much kinetic energy does the bobsled gain?

b. How much work did the bobsled team do? Explain how you found the answer.

c. If the teammates pushed the bobsled with a force of 500 N, over what distance did they apply the force?

d. Later, the bobsled is racing down the track at a speed of 28 m/s. With the team in it, the bobsled has a total mass of 430 kg. How much work must be done by air resistance to slow down the bobsled to 25 m/s?

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Answers (1)

Know the Answer?

Baron Blevins · Answer 1

a) KE=1/2 mv^2=1/2*150*4.2^2=1323 J

b) Work-energy theorem states that work equals the gained KE, so W=KE=1323 J

c) d=W/F=1323/500=2.65 m

d) Again apply work-energy theorem:

W=1/2*m (v2^2-v1^2) = 1/2*430 * (25^2-28^2) = --34.185 J