# Velocity vs. Acceleration: What's the Difference?

Edited by Janet White || By Harlon Moss || Updated on October 23, 2023
Velocity is the speed in a given direction, while acceleration is the rate of change of velocity over time.

## Key Differences

Velocity describes the speed of an object in a specific direction, making it a vector quantity. On the other hand, acceleration pertains to how fast or slow the velocity of an object changes over a period of time.
Velocity provides a clear snapshot of an object's movement at any given moment. In contrast, acceleration offers insight into the dynamics of that movement, revealing whether the object is speeding up, slowing down, or changing direction.
It's possible for an object to have a constant velocity, meaning its speed and direction remain unchanged. However, any variation in that velocity implies there's acceleration involved, even if it's just a change in direction without a change in speed.
The units of measurement for velocity typically involve distance over time, such as meters per second (m/s). Acceleration, being a rate of change in velocity, is measured in terms of velocity over time, like meters per second squared (m/s^2).
Velocity can be positive, negative, or zero, indicating direction and magnitude of motion. Acceleration, on the other hand, can be positive (speeding up), negative (slowing down, also known as deceleration), or zero (constant velocity).

## Comparison Chart

### Definition

Speed in a given direction.
Rate of change of velocity.

Vector.
Vector.

### Representation

Magnitude and direction of motion.
Changes in speed or direction.

### Units

Typically meters per second (m/s).
Typically meters per second squared (m/s^2).

### Static/Dynamic

Can remain constant.
Indicates a change in motion.

## Velocity and Acceleration Definitions

#### Velocity

Rate of change of an object's position.
With a consistent velocity, she completed the marathon in 4 hours.

#### Acceleration

Change in velocity over time.
The sports car has an impressive acceleration from 0 to 60 mph in 3 seconds.

#### Velocity

Can be constant or variable.
Despite challenges, the river maintained its velocity downstream.

#### Acceleration

Can be positive or negative.
Braking leads to negative acceleration or deceleration.

#### Velocity

Speed in a specific direction.
The car's velocity was 60 mph to the north.

#### Acceleration

Influenced by external forces.
The acceleration of gravity pulls objects toward Earth.

#### Velocity

Involves both magnitude and direction.
An object moving at 5 m/s eastward has a specific velocity.

#### Acceleration

A vector quantity, indicating direction of change.
The acceleration of the roller coaster was felt most during the steep drops.

#### Velocity

A vector quantity indicating magnitude and direction.
The velocity of the wind shifted from east to west.

#### Acceleration

Describes dynamics of movement.
The sudden acceleration made passengers grip their seats.

#### Velocity

Rapidity or speed of motion; swiftness.

#### Acceleration

The act of accelerating.

## FAQs

#### Can an object have zero velocity but non-zero acceleration?

Yes, like at the topmost point of a thrown object: it has zero velocity but gravity provides acceleration.

#### Can velocity be negative?

Yes, a negative velocity indicates motion in the opposite reference direction.

#### Is deceleration the same as negative acceleration?

Yes, deceleration refers to negative acceleration.

#### How do velocity and acceleration relate to Newton's laws?

Newton's second law connects force, mass, and acceleration, while his first involves objects at rest or constant velocity.

#### What is velocity in simple terms?

Velocity is the speed of something in a specific direction.

#### Can you feel acceleration?

Yes, humans can feel changes in acceleration but not constant velocity.

#### Why is acceleration crucial in car performance?

Acceleration indicates how quickly a car can increase its velocity.

#### How is acceleration caused in an object?

Acceleration is caused by external forces acting on an object.

#### Can acceleration occur in space?

Yes, spacecrafts can change their velocity through thrusters, causing acceleration.

#### What does acceleration indicate?

Acceleration indicates a change in velocity over time.

#### Can velocity change without acceleration?

No, any change in velocity indicates acceleration.

#### What's the Earth's acceleration due to gravity?

Approximately 9.81 m/s^2, influencing downward velocity of free-falling objects.

#### In which scenarios is velocity most observed?

Velocity is observed in anything that moves, from running athletes to orbiting planets.

#### How do velocity and speed differ?

Velocity has direction, while speed doesn't.

#### What unit measures acceleration?

Acceleration is typically measured in meters per second squared (m/s^2).

#### Which one is scalar: speed, velocity, or acceleration?

Speed is scalar; both velocity and acceleration are vectors.

#### What factors can influence acceleration?

Forces acting on an object can influence its acceleration.

#### Is velocity relative?

Yes, velocity is often relative to a reference point or observer.

#### How does direction factor into velocity?

Velocity is a vector, so it must have both magnitude (speed) and direction.

#### Can an object's velocity be constant?

Yes, if an object maintains the same speed and direction, its velocity is constant.