Which is not a way to transfer electric charges? a) by combustion b) by contact c) by friction d) by induction

Electric charge can be transferred by contact (touch a wire, get a shock), by friction (scuff on the carpet, zap your sister), and by induction (pick up bits of tissue with a charged glass rod).

But not by combustion. (A) You can't charge a battery by throwing it into the fire.  

acceleration = (change in speed) / (time for the change)

change in speed = (20-120)= -100 m/s.

1.5 min = 90 sec

acceleration = -100/90 = -1.11 m/s^2.

we don't care about the 150kg or the 2,500 meters. they don't make any difference.

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