UCSB Science Line
Sponge Spicules Nerve Cells Galaxy Abalone Shell Nickel Succinate X-ray Lens Lupine
UCSB Science Line
How it Works
Ask a Question
Search Topics
Our Scientists
Science Links
Contact Information
What are the equations of motion? Can you mention three of them?
Question Date: 2020-04-29
Answer 1:

Hi Tiago, this is a good question and it is definitely something you will have the opportunity to study if you choose to take physics classes. The basic equations of motion relate different values that can help you predict where an item will be some time after being pushed/pulled/thrown/shot/etc... from its initial starting point.

The three basic values you will need to know about are position, velocity, and acceleration. Position tells you about where something is. Velocity tells you about how fast something is going. Acceleration tells you about how quickly something's velocity is changing. These can be put together in the basic equations of motions as follows:

(1) Position = Initial position + (Velocity x time) + (1/2)(Acceleration x time2) This equation relates all three of the values we just talked about. It basically tells us that the position of something after a given amount of time is equal to its starting position added to its velocity multiplied by time (running 5 miles/hour for 1 hour means you've run 5 miles) added to its one half of the product of acceleration and time squared (acceleration is equal to 0 if your velocity does not change). The last part of the equation that involves acceleration allows us to account for changes in the velocity.

For example, if I, for 50 minutes at 5 miles per hour but during the last 10 minutes of my run, I steadily increase my speed from 5 miles per hour to 10 miles per hour, I will have run further than if I ran at 5 miles per hour for the full hour.

(2) Velocity = Initial velocity + (Acceleration x time) This equation relates the velocity of something after a given amount of time to the acceleration. It is saying that our velocity after a certain time is equal to our initial velocity plus the rate of change in our velocity multiplied by the amount of time it has been changing for.

So, if I start off running at 5 miles per hour and I have an acceleration of 1 mile per hour, per hour (meaning that every hour my velocity increases by 1 mile per hour), after one hour, my velocity will be 6 miles per hour.

Hopefully with these equations, you can start to understand how we can predict motion by using the relationships between those three important parameter: position, velocity, and acceleration.

Answer 2:

The laws of motion (notice that laws of motion is not the same as equations of motion) are laws set out by Isaac Newton to describe how inertia, force, and momentum work. One of these - Newton's second law, or the definition of force, has an equation: F = ma, where F is force, m is mass, and a is acceleration.

The other two laws establish that objects don't change the direction or speed of motion without a force, and that any force imparted by one object on another will be matched by an equal and opposite force in the other direction.

There are no formal equations of motion like Newton's laws of motion. There are, however, equations for angular force, or torque, which is like regular force, but applies to spinning bodies. Additionally, each fundamental force (gravity, electromagnetism, etc.) has its own equations that determine how strong each force is.

Answer 3:

F = m a
Force = mass x acceleration = Work
I asked a class of elementary school kids what Work was. I thought they'd say things like: 'Doing hard stuff.' My son raised his hand and said, "Work equals mass time acceleration." I asked him later how he knew that, and he said he learned it from some floppy disc for our computer.

F = ma is Newton's Second Law of Motion. Wikipedia tells about Newton's 3 laws of motion here:
Newton's laws of motion are three physical laws that, together, laid the foundation for classical mechanics. They describe the relationship between a body and the forces acting upon it, and its motion in response to those forces. Wikipedia.

Newton's First Law says things either stay sitting still, if they're sitting still; or they keep moving at the same speed, if they're moving, unless some force acts on them.

Newton's Third Law says: if one thing exerts a force on another thing, the other thing exerts the same force on the first thing, but the force is in the opposite direction.

Click Here to return to the search form.

University of California, Santa Barbara Materials Research Laboratory National Science Foundation
This program is co-sponsored by the National Science Foundation and UCSB School-University Partnerships
Copyright © 2020 The Regents of the University of California,
All Rights Reserved.
UCSB Terms of Use