(a) What is the maximum frictional force in the knee joint of a person who supports 66.0 kg of her mass on that knee? The coefficient of static friction between the bone and synovial fluid is 0.016 and the coefficient of kinetic friction between the bone and synovial fluid is 0.015. Enter to 3 significant figures Maximum frictional force in the knee joint N (b) During strenuous exercise it is possible to exert forces to the joints that are easily ten times greater than the weight being supported. What is the maximum force of friction under such conditions? Enter to 3 significant figures Maximum frictional force in the knee joint = N
Gravitational force
In nature, every object is attracted by every other object. This phenomenon is called gravity. The force associated with gravity is called gravitational force. The gravitational force is the weakest force that exists in nature. The gravitational force is always attractive.
Acceleration Due to Gravity
In fundamental physics, gravity or gravitational force is the universal attractive force acting between all the matters that exist or exhibit. It is the weakest known force. Therefore no internal changes in an object occurs due to this force. On the other hand, it has control over the trajectories of bodies in the solar system and in the universe due to its vast scope and universal action. The free fall of objects on Earth and the motions of celestial bodies, according to Newton, are both determined by the same force. It was Newton who put forward that the moon is held by a strong attractive force exerted by the Earth which makes it revolve in a straight line. He was sure that this force is similar to the downward force which Earth exerts on all the objects on it.
![### Frictional Force in the Knee Joint
**(a) Calculation of Maximum Frictional Force:**
What is the maximum frictional force in the knee joint of a person who supports 66.0 kg of her mass on that knee? The coefficient of static friction between the bone and synovial fluid is 0.016, and the coefficient of kinetic friction between the bone and synovial fluid is 0.015.
**Enter to 3 significant figures:**
- Maximum frictional force in the knee joint = [Input Box] N
---
**(b) Friction During Strenuous Exercise:**
During strenuous exercise, it is possible to exert forces on the joints that are easily ten times greater than the weight being supported. What is the maximum force of friction under such conditions?
**Enter to 3 significant figures:**
- Maximum frictional force in the knee joint = [Input Box] N
---
**Hint:**
In both parts, the maximum friction is asked. You may assume that the femur and the tibia are at rest with each other to calculate the **upper limit of the friction force**.
---
**Reflect:**
Are the frictional forces large or small? To conclude that a quantity is big or small, you need to compare it with some known quantity. In this problem, what would be a good force to compare the frictional force with?
You may compare the magnitude to the weight supported by the knee. When can these forces become significant?](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F5a3df371-d475-482a-84ce-057c931f1fc6%2F4195759d-5dd4-4b38-b054-22cd2e5ff2ba%2Fntpnit_processed.png&w=3840&q=75)
Trending now
This is a popular solution!
Step by step
Solved in 3 steps with 2 images
