You are Here: Home >< Maths

# When resolving forces, what does the ma part of it actually mean?? watch

1. Lets say I was resolving forces(down being positive) for a particle, and its weight was 5g, the equation you would form is 5g=5a.

If you add a resistive force, it becomes 5g-R=5a.
Rearrange that for R and you get R=5g-5a.
I get that 5g is the weight of the particle, but what does the ma part actually tell us?

I'm not really sure if I worded it in the best way, and so I hope it doesn't sound like a stupid question.

Essentially, if R=5g-5a
It's saying the resistive force = the weight of the particle - 5a.
I don't get what the 5a is actually telling us.. hope that makes it a bit clearer.
2. (Original post by dont know it)
Lets say I was resolving forces(down being positive) for a particle, and its weight was 5g, the equation you would form is 5g=5a.

If you add a resistive force, it becomes 5g-R=5a.
Rearrange that for R and you get R=5g-5a.
I get that 5g is the weight of the particle, but what does the ma part actually tell us?

I'm not really sure if I worded it in the best way, and so I hope it doesn't sound like a stupid question.

Essentially, if R=5g-5a
It's saying the resistive force = the weight of the particle - 5a.
I don't get what the 5a is actually telling us.. hope that makes it a bit clearer.
It's just telling us the net force.
3. (Original post by RDKGames)
It's just telling us the net force.
Thanks. Still confused though. Where does the ma part come from? The 5g is the weight, but what is the 5a?
4. (Original post by dont know it)
Thanks. Still confused though. Where does the ma part come from? The 5g is the weight, but what is the 5a?
It's just one of Newton's laws. Can't tell you where it came from. (physical observations?)

is the gravitational force on the particle, and is defined to be the net force acting on the particle, so that's what it is.
5. ma = mass x Accerlation
since mass is 5 5xA = 5A
6. (Original post by RDKGames)
It's just one of Newton's laws. Can't tell you where it came from. (physical observations?)

is the gravitational force on the particle, and is defined to be the net force acting on the particle, so that's what it is.
Oh, thank you!
7. We know the force applied is proportional to the acceleration of an object.
(If you pull an object with a spring, keeping the spring's extension constant, then the object undergoes constant acceleration.
If you use two springs with the same acceleration, then the acceleration doubles, and so on.)

We also know that more massive objects need a greater force to reach the same acceleration.
(If you replace the object with one twice as massive, and use the same extension on the spring, then it experiences half the acceleration)

Therefore the force applied equals the object's mass times the acceleration caused by the force, and F = ma

...

When we speak of an objects weight being mg, that is actually the same thing as ma, because the Earth's gravity always pulls objects towards itself at g m/s if they are not supported by a reaction force. The weight is another way of saying the force an object experiences due to the Earth's gravite, and so is found by F = ma, where a = g.

### Related university courses

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: March 6, 2018
The home of Results and Clearing

### 1,378

people online now

### 1,567,000

students helped last year
Today on TSR

### IT'S TODAY!

A-level results chat here

### University open days

1. London Metropolitan University
Sat, 18 Aug '18
2. Edge Hill University
Sat, 18 Aug '18
3. Bournemouth University
Sat, 18 Aug '18
Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams