How Do Forces Affect Hanging Blocks Connected by Ropes?

[mattw4466]

Blocks A, B and C hang from the ceiling and are
connected by three ropes labeled 1, 2 and 3. Block
A weighs 10 lbs, block B weighs 5 lbs and block C
weighs 20 lbs.

a. List the forces acting on block A, compute
their magnitudes and draw a free-body
diagram.

b. List the forces acting on block B, compute
their magnitudes and draw a free-body
diagram.

c. List the forces acting on block C, compute
their magnitudes and draw a free-body
diagram.


Be sure to draw force vectors with a length
proportional to the magnitude of each
force. Label tension with the rope number
(e.g. T2) and weight with the block letter
(e.g. wC).

 

[hage567]

Hi mattw4466,

Please show an attempt at solving this problem. Explain what part is confusing you. No one here is going to just hand a solution to you.

 

[nlightner]

a. The forces acting on block A are the tension force from rope 1 (T1) and the weight force of the block (wA). The magnitude of T1 can be calculated using the formula T = mg, where m is the mass of the block and g is the acceleration due to gravity (9.8 m/s^2). Therefore, T1 = (10 lbs)(9.8 m/s^2) = 98 N. The magnitude of wA is simply its weight, which is 10 lbs or 98 N. The free-body diagram for block A would show a vector pointing down for wA and a vector pointing up and to the left for T1.

b. The forces acting on block B are the tension forces from ropes 1 and 2 (T1 and T2) and the weight force of the block (wB). The magnitude of T1 and T2 can be calculated using the same formula as before, since both ropes are connected to block B. Therefore, T1 = (5 lbs)(9.8 m/s^2) = 49 N and T2 = (5 lbs)(9.8 m/s^2) = 49 N. The magnitude of wB is 5 lbs or 49 N. The free-body diagram for block B would show a vector pointing down and to the left for wB, a vector pointing up and to the right for T1, and a vector pointing up and to the left for T2.

c. The forces acting on block C are the tension forces from ropes 2 and 3 (T2 and T3) and the weight force of the block (wC). Using the same formula as before, T2 = (20 lbs)(9.8 m/s^2) = 196 N and T3 = (20 lbs)(9.8 m/s^2) = 196 N. The magnitude of wC is 20 lbs or 196 N. The free-body diagram for block C would show a vector pointing down for wC and two vectors pointing up and to the right for T2 and T3.