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A cyclist intends to cycle up a 7.8° hill whose vertical height is 150 m. Assuming the
Chapter 6, Problem 46P(choose chapter or problem)
Problem 46P
A cyclist intends to cycle up a 7.8° hill whose vertical height is 150 m. Assuming the mass of bicycle plus cyclist is 75 kg, (a) calculate how much work must be done against gravity, (b) If each complete revolution of the pedals moves the bike 5.1 m along its path, calculate the average force that must be exerted on the pedals tangent to their circular path. Neglect work done by friction and other losses. The pedals turn in a circle of diameter 36 cm.
Questions & Answers
QUESTION:
Problem 46P
A cyclist intends to cycle up a 7.8° hill whose vertical height is 150 m. Assuming the mass of bicycle plus cyclist is 75 kg, (a) calculate how much work must be done against gravity, (b) If each complete revolution of the pedals moves the bike 5.1 m along its path, calculate the average force that must be exerted on the pedals tangent to their circular path. Neglect work done by friction and other losses. The pedals turn in a circle of diameter 36 cm.
ANSWER:
Solution
Step 1 of 2
- We need to find out how much work must be done against gravity.
The work done against gravity is nothing but the change in the potential energy.
Given,
The mass of bicycle plus cyclist is
The vertical height of the hill is
So,
The work done against the gravity is .