Wave 1
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Resulting
Wave
Wave 2
Wave 2 Phase Shift

The resulting wave has the largest possible amplitude when Wave-1 and Wave-2 are exactly in step ... their peaks both happen at the same time and their troughs both happen at the same time.

This means that Wave-1 and Wave-2 have the same frequency, and the phase shift from one wave to the other is zero.

When all of that happens, the amplitude of the resulting wave is the sum of the amplitudes of Wave-1 and Wave-2.  If Wave-1 and Wave-2 have the same amplitude, then the resulting wave will have double that amplitude.

it's a b and

the best answer for these questions would be:

1.            c. is smaller

2.            d) concrete operational

3.            b) interaction with the environment – the children interact with their environment can them learn more.

4.            a) parents who reason openly with children can limit a child’s cognitive ability.