Final answer:
Marcel Breuer was the designer who created the first flexible joint for a chair, paving the way for modern furniture design. Breuer's use of tubular steel allowed chairs to have strength and a shock absorber-like flexibility.
Step-by-step explanation:
The designer of the first flexible joint for a chair, similar to a shock absorber, was Marcel Breuer. Breuer was an influential modernist architect and furniture designer, known for his use of tubular steel. This development in furniture design occurred during the Bauhaus era, where innovation and functionality were heavily emphasized. Breuer's chairs, including his Wassily Chair and Cesca Chair, utilized tubular steel to provide both strength and flexibility, signaling an evolution in modern furniture design. While Ludwig Mies van der Rohe is acclaimed for his iconic Barcelona Chair, it was Breuer who pioneered the use of flexible, tubular steel in furniture, giving chairs a kind of built-in 'shock absorber' feature.