Question

use the passage to answer the question. how do oreilly and his graduate students test their theory that the physics of running and walking cause shoelace knots to come undone? select the two correct answers. (1 point) they used a high - speed camera to monitor movement on a treadmill. they stamped their feet on the ground. they attached devices to the laces to measure acceleration. they tied a variety of knots with various strengths. they swung their feet. check answer remaining attempts : 3 \science: why shoelace knot failure\ by nsikan akpan right off the bat, they found shoelaces didnt untie when a person just swung their foot nor when they only stamped the ground. the combination of the two activities, which define walking and running, appeared responsible. the team acquired a high - speed camera and pointed it at greggs shoes as she ran on a treadmill. gregg had tied her laces with one of two knots: square (strong) knot or a granary (weak) knot. heres how oreilly described the difference between the two: you tie the laces first. thats where you loop the strands together, one around the other. next, you form the \bunny\ knots. if you loop the bunny knots together the same direction that you tied the first knot together, thats a weak knot. but if you do the opposite. instead of putting one over the other, you switch the order, then you get the strong knot. what the team noticed in the videos was nothing happened for a long time, and then — all of the sudden — the laces came untied, typically over the course of two strides. it didnt matter if gregg had used a strong knot or a weak knot. to break down the physics of the phenomena, the researchers attached a small device to the free end of the laces that measured acceleration, and then gregg went for a walk or a jog. this acceleration creates inertia, which is the tendency for an object to keep moving once it is in motion.

Explanation:

The passage states that the team used a high - speed camera to monitor movement on a treadmill and attached devices to the laces to measure acceleration to test their theory. Stamping feet or swinging feet alone didn't cause laces to untie, and tying different knots was not part of the testing method for the theory about why laces come undone during walking and running.

Answer:

They used a high - speed camera to monitor movement on a treadmill.
They attached devices to the laces to measure acceleration.