# Velocity and Acceleration

#### Academic Questions in PhysicsPlease check out our Test Your Knowledge page to see all Questions and Answers The Law of Inertia is also referred to as _____. A. 1st Law of Thermodynamics B. 2nd Law of Thermodynamics C. 3rd Law of Thermodynamics D. Newton's 1st Law of Motion E. Newton's 2nd Law of Motion F. Newton's 3rd Law of Motion The process whereby the velocity of an object increases and decreases over a period of time is best associated with the term _____. A. Speed B. Velocity C. Momentum D. Constant Velocity E. Acceleration F. Average Velocity The rate of motion is best referred to as _____. A. Speed B. Velocity C. Momentum D. Inertia E. Acceleration F. Constant Velocity Consider this expression below: A body X exerts a force FX on another body Y. In return, body Y exert a force FY back on body X. The forces FX and FY are equal in magnitude but opposite in direction. Putting the above expression into equation: FX = -FY Where FX is the action force FY is the reaction Force The above expression relates to _____. A. Theory of Force B. Force Postulate C. Einstein's proposal on Relativity D. Newton's 1st law of motion E. Newton's 2nd law of motion F. Newton's 3rd law of motion The tendency of a body to remain in a state of rest or in uniform motion is referred to as _____. A. tension B. uniform acceleration C. constant acceleration D. deceleration E. inertia F. velocity A change in the position of an object with reference to time is best described as _____. A. momentum B. displacement C. velocity D. acceleration E. direction F. motion The saying "what goes up on earth must come down" can be best attributed to _____. A. force B. motion C. mass D. acceleration E. average velocity F. constant velocity We have _____ laws of Thermodynamics. A. 1 B. 2 C. 3 D. 4 E. 5 D. 6 For a free trial, click here. Recommend to a school and get 25% commission for 6 academic terms

### What is Velocity?

Although velocity and speed are often used interchangeably by students, they are NOT the same thing. As a student, you will need an understanding on motion and speed to better comprehend velocity and acceleration.

The direction in which an object is moving is what differentiates velocity from speed.

Velocity can be defined as speed in a given direction.

Velocity can also be defined as the rate of change of displacement.

Velocity = Change in distance/Change in time

Note: Velocity is a vector quantity because it has both magnitude and direction.

Below is a narrative that differentiates speed from velocity:

A bus is moving on a highway at a speed of 100 meters per 20 seconds. If the bus changes its direction and moves at a different speed (or even the same speed), then that's velocity.

As an instance, the bus (above) may move at a velocity of 100m/20s in the northern direction and 100m/20s in the eastern direction.

Note: Speed and velocity both have the same Standard International (SI) unit which is meter per second (m/s).

### Acceleration

The velocity of a moving object can either decrease or increase over a period of time; and this is where acceleration comes into play. Consider the instance below:

When you ride a bicycle, you start slowly but as soon as you increase the push on the pedals, the bicycle moves faster (accelerate). When you stop pushing the pedals, the bicycle begins to move slowly (negative acceleration).

From the above instance, we can therefore say that acceleration can also be negative.

Note: Deceleration is an English term used to describe negative acceleration; but in physics, we use the term acceleration to denote both the positive and negative changes in velocity.

Acceleration can be defined as the rate of change of velocity.

Acceleration is also defined as the measurement of how much the velocity of an object changes with time.

Acceleration = Change in velocity/Change in time

If an object changes velocity after a fixed amount of time, then such acceleration is said to be constant (that is: constant acceleration).

Consider the instance below:

If we throw a table tennis ball down a slope, it will roll downwards more rapidly at each second.

On the 1st second, let's assume it's velocity to be 20m/s.

On the 2nd second, its velocity becomes 25m/s.

On the 3rd second, it becomes 30m/s.

With regards to the above velocities, such ball is said to have a constant acceleration of 5m/s.

This means that: for every 5 meters moved, the tennis ball accelerates by 1 second.

Note: Average acceleration is the total change in velocity over a period of time, divided by the duration of that period.

Acceleration is a vector quantity and its Standard International (SI) unit is meter per second (m/s) or meter per second square (m/s2). Alfred Ajibola is a Medical Biochemist, a passionate Academician with over 7 years of experience, a Versatile Writer, a Web Developer, a Cisco Certified Network Associate and a Cisco CyberOps Associate.

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