Question: in fracture mechanics the symbol k stands for
[{'answer': 'the stress intensity factor', 'provenance': [{'wikipedia_id': '16717', 'title': 'K', 'start_paragraph_id': 41, 'start_character': 60, 'end_paragraph_id': 41, 'end_character': 87, 'bleu_score': 1.0, 'section': 'Section::::Other usage.\n'}]}, {'provenance': [{'wikipedia_id': '16717', 'title': 'K', 'start_paragraph_id': 41, 'start_character': 0, 'end_paragraph_id': 41, 'end_character': 87, 'bleu_score': 0.8385766789076251, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 3050340231579425756}, 'section': 'Section::::Other usage.\n'}]}]