Physics anatomy and force problem

Question

When you bend your knee, the quadriceps muscle is stretched. This increases the tension in the quadriceps tendon attached to your kneecap (patella), which, in turn, increases the tension in the patella tendon that attaches your kneecap to your lower leg bone (tibia). Simultaneously, the end of your upper leg bone (femur) pushes outward on the patella.  The angle in the problem is 42 '

-What size force does the femur exert on the kneecap if the tendons are oriented as in the figure and the tension in each tendon is 60 N?

Answer 1

To solve this problem, we can use the principle of forces and trigonometry.

Let's denote the angle between the tendons and the femur as θ=42'

you can convert it to degrees by dividing by 60 (since 1 degree = 60 minutes):

42′÷60=0.7^∘

The force exerted by the femur on the kneecap can be calculated using the following relation:

Force by femur=Tension in tendon × 1/sin(θ)

Given that the tension in each tendon is 60 N and the angle is 0.7 degrees, we can substitute these values into the formula:

Force by femur= 60 N× 1/sin⁡(0.7^∘)

Let's calculate this:

Force by femur= 60 N× 1/sin⁡(0.7∘)

≈5141N

So, the force exerted by the femur on the kneecap is approximately 5141 N