I don't know for sure but i think that it is because the force him pushing her pushed him back as well
Hope i helped
Interval training is simply alternating short bursts (about 30 seconds) of intense activity with longer intervals (about 1 to 2 minutes) of less intense activity. For instance, if your exercise is walking and you're in good shape, you might add short bursts of jogging into your regular brisk walks.
The answer is a because if you look really close
I believe it is acceleration!
