Impulse
Part of speech: noun
Definition: A wish or urge, particularly a sudden one. The integral of force over time.
Example sentence: There's only one thing harder than living in a home with an adolescent - and that's being an adolescent. The moodiness, the volatility, the wholesale lack of impulse control, all would be close to clinical conditions if they occurred at another point in life. In adolescence, they're just part of the behavioral portfolio.
Impetus
Part of speech: noun
Definition: Something that impels, a stimulating factor.A force, either internal or external, that impels; an impulse.The force or energy associated with a moving body; a stimulus.An activity in response to a stimulus.
Example sentence: I got out of the Army - in my world - I came to New York, for instance, when the civil rights movement was just beginning, and that created a certain energy, a certain rumble, a certain impetus for black actors.