She can put chalk in vinegar as the vinegar will disintegrate the chalk chemically demonstrating chemical changes. But for physical changes she can break the chalk into small pieces by smashing it with something or her hand.
The distance between object P1 and its image formed is determined as 36 m.
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Distance of the image</h3>
The distance of the image formed by object P1 is calculated as follows;
In a plane mirror; object distance = image distance
image distance of P1 = 18 m
distance between object and image = 18m + 18 m = 36 m
Thus, the distance between object P1 and its image formed is determined as 36 m.
Learn more about plane mirrors here: brainly.com/question/1126858
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When a current flows through coil, magnetic field is produced around the coil which induces emf also known as back emf. When current in the coil is increased, more magnetic field is produced which in turn increases the induced emf.