# Physics P2 1.2 Velocity and acceleration.

What is velocity?
It is speed in a given direction.
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What is the change of velocity per second?
Acceleration.
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What is the equation for acceleration?
a = v-u over t (look up).
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What is the speed of an object in a given direction?
Its velocity.
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What happens when an object changes direction, even if its speed stays the same?
The velocity of the object changes.
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What do we say if the velocity of an object changes?
We say that it accelerates.
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In the equation for acceleration, what is a?
The acceleration in metres per second squared (m/s^2).
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In the equation for acceleration, what is v?
The final velocity in metres per second (m/s).
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In the equation for acceleration, what is u?
The initial velocity in metres per second (m/s).
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In the equation for acceleration, what is t?
The time taken for the change in seconds (s).
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What does it mean if the value calculated for acceleration is negative?
The body is decelerating (slowing down).
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What a negative acceleration the same as?
A deceleration.
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What is the difference between speed and velocity?
Velocity is speed in a particular direction.
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What is the SI unit of acceleration?
Metres per second squared (m/s^2).
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**BE SURE TO LEARN THE UNITS HERE CAREFULLY**
**DON'T CONFUSE m/s (UNIT OF SPEED AND VELOCITY) AND m/s^2 (UNIT OF ACCELERATION).
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## Other cards in this set

### Card 2

#### Front

What is the change of velocity per second?

Acceleration.

### Card 3

#### Front

What is the equation for acceleration?

### Card 4

#### Front

What is the speed of an object in a given direction?

### Card 5

#### Front

What happens when an object changes direction, even if its speed stays the same?