Aparent pushes a stroller with a 11.2 n force for 15.9 m. how much work did the parent do?

The definition of work is that it is the Force applied over a distance, times the distance. The only trick is that you have to account only for forces in the direction of movement; any forces that are normal to the movement are not taken into account. Intuitively, work is generated only by forces that contribute  to the movement (or go against it; same or opposite direction).

Let us see now: W=F*d =11.2N* 15.9m=178.1 N*m=178.1 J where J stands for Joules. This is the work that the parent did, namely how much energy he had to put in to move the stroller.

Letter a, because when there are unlike charges they will always attract to each other.

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