Question

5) why are at least two muscles needed to move a bone at a joint in one direction

Answer 1

at Least two muscles r needed to move bone in a direction as one is needed to lift the bone (contract ) and other to release down the bone ( relax )

Answer 2

Usually, two skeletal muscles are joined to a bone.

When one muscle contracts in a direction for making a movement for the bone, the other muscle relaxes to facilitate the bone movement.

Bones may be light but are strong enough to support the entire weight of the system and therefore, they are important for making a movement.

Bones are there in the entire body from head to toe and help in making movements successfully.