Identify which of the following cases occurs due to the effect of magnetic force.
Breaking of a walnut with a magnet.
Attaching a piece of paper to the refrigerator with a magnet.
Crashing into each other of two magnets placed close to each other.
Falling of a magnet from a height to the ground.
Picking up coins from the ground with a magnet.
Pulling of a small metal car on the ground with a magnet.
