Answer:
a) 0.049 m
b) Yes, increase
Explanation:
Draw a free body diagram.
In the y direction, there are three forces acting on the feeder. Â Two vertical components of the tension forces in each rope pulling up, and weight force pulling down.
Apply Newton's second law to the feeder in the y direction.
∑F = ma
2Ty − mg = 0
Ty = mg/2
Let's say the distance the rope sags is d. Â The trees are 4m apart, so the feeder is 2m horizontally from either tree. Â Using Pythagorean theorem, we can find the length of the rope on either side:
L² = 2² + d²
L = √(4 + d²)
Using similar triangles, we can write a proportion using the forces and distances.
Ty / T = d / L
Substitute:
(mg/2) / T = d / √(4 + d²)
Solve for d:
Td = mg/2 √(4 + d²)
T² d² = (mg/2)² (4 + d²)
T² d² = (mg)² + (mg/2)² d²
(T² − (mg/2)²) d² = (mg)²
d² = (mg)² / (T² − (mg/2)²)
d = mg / √(T² − (mg/2)²)
Given m = 2.4 kg and T = 480 N:
d = (2.4) (9.8) / √(480² − (2.4×9.8/2)²)
d = 0.049 m
b) If a bird lands on a feeder, this will increase the tension in the rope to support the bird's weight.