Question: waves that need matter to carry energy are called
[{'answer': 'mechanical', 'provenance': [{'wikipedia_id': '162312', 'title': 'Mechanical wave', 'start_paragraph_id': 1, 'start_character': 2, 'end_paragraph_id': 1, 'end_character': 12, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '162312', 'title': 'Mechanical wave', 'start_paragraph_id': 1, 'start_character': 0, 'end_paragraph_id': 1, 'end_character': 561, 'bleu_score': 0.977397480575333, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 15580029538676948403}, 'section': 'Section::::Abstract.'}]}]