x Turn on thread page Beta
 You are Here: Home >< Physics

# Speed=Distance/Time watch

1. Hey,

I'm going into 5th year and plan on crashing Higher Phyics. I've started to teach myself a little and hae grasped it slightly.

My book that I'm using has the Data Shet and the Relationships/Equations needed for the exam and I understand you need to know teh Equations but not the Data Sheet.

Anyway Speed=Distance/Time. I understand this and I also understand what Distance and Time equal and can figure them out comfortably enough.

Although in my book it says you can also right this down as:

V=d/t

or

V=s/t

The book's relationships have Speed=d/t down as: S=vt, which is equalivant to V=s/t and not V=d/t. But what I don't understand is why it's not just written as S=d/t?

In these, what do the letters stand for?

V=d/t

or

V=s/t

Thanks for helping.

PS. In an exam if I rembered it as Speed=Distance/Time and wrote that down, or S=d/t, will I still be given the mark?
2. V is velocity - this is speed and direction
S means diSplacment, this is the distance from the starting point to the end point, rather than the actual distance of the journey.
3. (Original post by allypallywally)
V is velocity - this is speed and direction
S means diSplacment, this is the distance from the starting point to the end point, rather than the actual distance of the journey.
So in s=vt,

t=time
v=speed
s= distance

Therefore it equals: Distance=speed x time.

Also in an exam am I expected to use the official relationships or can I right them down as words? Or should I just learn both?
4. (Original post by JaggySnake95)
So in s=vt,

t=time
v=speed
s= distance

Therefore it equals: Distance=speed x time.

Also in an exam am I expected to use the official relationships or can I right them down as words? Or should I just learn both?
You need to be comfortable using the symbolic equations. At the same time, you must understand what they mean, or you won't be able to use them. Writing things out in full simply isn't practical when you have things like Coulomb's law:

5. (Original post by BJack)
You need to be comfortable using the symbolic equations. At the same time, you must understand what they mean, or you won't be able to use them. Writing things out in full simply isn't practical when you have things like Coulomb's law:

Ok so you nee to know both but the exam requires letter formula?

Btw what level is that equation?
6. Also can I just use v=d/t?

for Speed=distance/time?
7. (Original post by JaggySnake95)
Ok so you nee to know both but the exam requires letter formula?
Yes. (And yes, v = d/t is fine for speed.)

Btw what level is that equation?
It should be higher level. You can't do much on electrostatics without it, but maybe that's all AH.

Coulomb's law relates the force between two given charges and the distance between them. It looks a bit scary but is just a constant so it's a simple inverse square law.
8. (Original post by JaggySnake95)
Hey,

I'm going into 5th year and plan on crashing Higher Phyics. I've started to teach myself a little and hae grasped it slightly.

My book that I'm using has the Data Shet and the Relationships/Equations needed for the exam and I understand you need to know teh Equations but not the Data Sheet.

Anyway Speed=Distance/Time. I understand this and I also understand what Distance and Time equal and can figure them out comfortably enough.

Although in my book it says you can also right this down as:

V=d/t

or

V=s/t

The book's relationships have Speed=d/t down as: S=vt, which is equalivant to V=s/t and not V=d/t. But what I don't understand is why it's not just written as S=d/t?

In these, what do the letters stand for?

V=d/t

or

V=s/t

Thanks for helping.

PS. In an exam if I rembered it as Speed=Distance/Time and wrote that down, or S=d/t, will I still be given the mark?
s=vt means the displacement (not speed) is equal to the velocity times time. This comes from the fact that velocity is the rate of change of displacement (with respect to time): v = s/t.

Don't worry though, it sounds as though your book is rather unclear: it is mixing up speed and velocity. It really should state that:

Average Speed = distance/time
Average Velocity = displacement/time

In some books/on some sites it does say that velocity = distance/time but I think that it just confuses people. Everything would be simpler if the correct terms were used!
9. (Original post by JaggySnake95)
Also can I just use v=d/t?

for Speed=distance/time?
Not a good idea as speed and velocity are not the same things; you might lose marks.
10. (Original post by Maths_Lover)
Not a good idea as speed and velocity are not the same things; you might lose marks.
The standard grade past papers answer guide say's that's what you should use?
11. (Original post by JaggySnake95)
The standard grade past papers answer guide say's that's what you should use?
Good for them. Who cares what they say, you shouldn't mix up speed and velocity, that's a simple fact. It'll get you in good practice to differentiate between the two, you won't be marked down, so you may as well learn which to use now.
12. (Original post by You Failed)
Good for them. Who cares what they say, you shouldn't mix up speed and velocity, that's a simple fact. It'll get you in good practice to differentiate between the two, you won't be marked down, so you may as well learn which to use now.
Ok, It's just I wouldn't want to be marked down that's all.

I'm getting told by people at school that the equation for it (as they have been taught) is V=d/t which is stupid because that means Velocity=distance/time..

To make things clear, what should I use for Speed and what should I use for velocity?
13. (Original post by JaggySnake95)
Ok, It's just I wouldn't want to be marked down that's all.

I'm getting told by people at school that the equation for it (as they have been taught) is V=d/t which is stupid because that means Velocity=distance/time..

To make things clear, what should I use for Speed and what should I use for velocity?
It really depends on what you're looking at. If the question is just about a particle moving in some trajectory that doesn't go back on itself, then the average velocity can just be calculated using the distance and that's perfectly fine, however, if the trajectory is one in which say, a particle goes forwards a distance x and then goes back a distance 2x, the displacement is going to be -x and in order to calculate the velocity (which is direction dependant since it's a vector) then you need to use the displacement, -x, not the distance 3x.
14. (Original post by You Failed)
It really depends on what you're looking at. If the question is just about a particle moving in some trajectory that doesn't go back on itself, then the average velocity can just be calculated using the distance and that's perfectly fine, however, if the trajectory is one in which say, a particle goes forwards a distance x and then goes back a distance 2x, the displacement is going to be -x and in order to calculate the velocity (which is direction dependant since it's a vector) then you need to use the displacement, -x, not the distance 3x.
Are you sure that is all standard grade?
15. (Original post by JaggySnake95)
Are you sure that is all standard grade?
What do you mean?
16. (Original post by You Failed)
Good for them. Who cares what they say, you shouldn't mix up speed and velocity, that's a simple fact. It'll get you in good practice to differentiate between the two, you won't be marked down, so you may as well learn which to use now.
(Original post by You Failed)
It really depends on what you're looking at. If the question is just about a particle moving in some trajectory that doesn't go back on itself, then the average velocity can just be calculated using the distance and that's perfectly fine, however, if the trajectory is one in which say, a particle goes forwards a distance x and then goes back a distance 2x, the displacement is going to be -x and in order to calculate the velocity (which is direction dependant since it's a vector) then you need to use the displacement, -x, not the distance 3x.
This.

It annoys me to see some Physics textbooks giving the wrong information about these things (e.g. difference between speed/velocity, mass/weight etc). The exam board should know better too, confusing all those people out there...
17. (Original post by JaggySnake95)
Are you sure that is all standard grade?
What is standard grade? Also, what level is Higher equivalent to? GCSEs? A-level? I am not quite sure...
18. (Original post by Maths_Lover)
What is standard grade? Also, what level is Higher equivalent to? GCSEs? A-level? I am not quite sure...
Sorry, as far as I am aware:

Higher=AS Level

The reason I don't understand most of what you are saying is that I've only just started learning any physics at all. I'm planning on crashing Higher (AS) so I've started to get a basic understanding of the subject. What I've gathered so far in terms of Speed, Distance, Time is:

That speed and velocity are the same in a general sense, except in physics and maths, velocity involves the direction/angle of which the speed is applied?

the equations for them both are:

Speed=distance/time or v=d/t

and

Velocity=displacement/time or v=s/t

That's what I've gathered so far, although at Standard Grade, because no question requires an angle/direction either equation is accepted.

Tell me if any of this is wrong.
19. (Original post by JaggySnake95)
Sorry, as far as I am aware:

Higher=AS Level

The reason I don't understand most of what you are saying is that I've only just started learning any physics at all. I'm planning on crashing Higher (AS) so I've started to get a basic understanding of the subject. What I've gathered so far in terms of Speed, Distance, Time is:

That speed and velocity are the same in a general sense, except in physics and maths, velocity involves the direction/angle of which the speed is applied?

the equations for them both are:

Speed=distance/time or v=d/t

and

Velocity=displacement/time or v=s/t

That's what I've gathered so far, although at Standard Grade, because no question requires an angle/direction either equation is accepted.

Tell me if any of this is wrong.
Sorry for the wait, I had to go for a while.

Ah I see now about the equivalent. So you are trying to teach yourself higher? That's cool.

This is basically right, although can be explained much better using calculus. How good is your Maths? If you have learned some calculus then I can give you a much better explanation of what they are that is a bit more accurate than the one in your textbook.
20. (Original post by Maths_Lover)
Sorry for the wait, I had to go for a while.

Ah I see now about the equivalent. So you are trying to teach yourself higher? That's cool.

This is basically right, although can be explained much better using calculus. How good is your Maths? If you have learned some calculus then I can give you a much better explanation of what they are that is a bit more accurate than the one in your textbook.
My maths is fairly good I'm doing Intermediate which is in-between standard grade and higher and done Straight Lines and differentiation at higher.

I'm doing higher physics next year at school but trying to teach myself some Standard Grade first.

EDIT: Now that I remember differentiation and Calculus is the same topic, so I've done that at higher. Go ahead and I'll see if I understand.

Turn on thread page Beta
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 20, 2011
Today on TSR

### Four things top students are doing

Over the Easter break

### Her parents made her dump me

Poll

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE