Englishfor English speakers
back
Preposition
—
Toward the rear.
He went back behind the stands.
—
To a place again.
I didn't like it, so I sent it back.
He went back to the same house.
They came back again.
back
Noun
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The back is the rear part of something; it is the part in the other direction from the front.
I went to the back of the house.
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The back is the rear part of the human body.
He had a scar on his back.
back
Verb
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If you back something, you support it.
The Republicans backed the bill.
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If you back up, you move backward.
He put the car in gear and backed right into the garage door.
impulse
Noun
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A desire to do something.
The impulse to learn led me to study day and night.
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A thrust; a push; a sudden force.
Pushing an object gives it an impulse.
—
The effect (integral) of force over time.
The total impulse from the impact will depend on the kinetic energy of the bullet.