# Help with this physicsWatch

Announcements
#1 Thanks, I have no idea how to do question 4 and 5, could someone explain it to me, thanks.
0
3 years ago
#2
(Original post by JerryG) Thanks, I have no idea how to do question 4 and 5, could someone explain it to me, thanks.
I think Pythagoras can give you the magnitude and trig the direction for Q4
0
#3
(Original post by 123Master321)
I think Pythagoras can give you the magnitude and trig the direction for Q4
There are no distances on the Axed though, just speeds
0
3 years ago
#4
(Original post by JerryG)
There are no distances on the Axed though, just speeds
Yh but its the same if instead of velocity you used force. Imagine the combined effect of going 50m/s north and 30m/s east if that helps
0
#5
(Original post by 123Master321)
Yh but its the same if instead of velocity you used force. Imagine the combined effect of going 50m/s north and 30m/s east if that helps
So how would I use that to work out direction?
0
3 years ago
#6
(Original post by JerryG)
So how would I use that to work out direction?
tan(theta) = 5/3
0
3 years ago
#7
Direction is the angle, once you find out all 3 sides of the right angles triangle by using pythagoraus then you can use tan x = o/h to find the angle
O = side opposite angle
H = hypotneuse
Then do inverse tan x to find x

Posted from TSR Mobile
0
#8
(Original post by 123Master321)
tan(theta) = 5/3

Right thanks, any idea on the next question?
0
3 years ago
#9
(Original post by JerryG)
Right thanks, any idea on the next question?
What is N and N0
0
#10
(Original post by 123Master321)
What is N and N0
I have no idea, I've just been set this work in prep for starting a level.
0
3 years ago
#11
(Original post by JerryG)
I have no idea, I've just been set this work in prep for starting a level.
Heard of logarithms before and I think it was from a-level maths. So probably go on exam solutions and go to the index and find logs, then see if you can turn what it's saying into a straight line equation then you u should be good from there
my bridging work was just some advanced gcse stuffy and a few easy
a-level stuff like suvat

Posted from TSR Mobile
0
3 years ago
#12
(Original post by JerryG)
Right thanks, any idea on the next question?

log(N) = log(N0)-hg

See what that gives you in terms of y = mx+c
0
3 years ago
#13
(Original post by Flame Alchemist)

log(N) = -hg log(N0)

See what that gives you in terms of y = mx+c
Instead of log, you want ln right?
0
3 years ago
#14
(Original post by 123Master321)
Instead of log, you want ln right?
Assuming natural base, yeah. It's all used confusingly interchangeably in different texts. But you're right that's it's usually best to specify.
0
3 years ago
#15
Logs in physics. This looks like more of a maths question. I did experimental data questions like this in maths.

Posted from TSR Mobile
0
#16
I looked online, but can only find logs with numbers, never things like N and NO
0
3 years ago
#17
(Original post by JerryG)
I looked online, but can only find logs with numbers, never things like N and NO
Okay, since you're struggling to gain a footing, I'll explain the answer to you.

Logarithms are essentially the inverse of exponentiation, so we can use them to construct direct, linear proportionalities from exponential relations. Know that the natural logarithm (ln) is log of base e, such that ln(e) = 1.

In this equation, N is the variable to track, whereas N0 is the initial value of N. It's not clear which of h and g is variable or constant, but let's assume g is variable.

ln(N) = ln(N0e^-hg)

ln(N) = ln(N0) + ln(e^-hg)

ln(N) = ln(N0) - hg ln(e)

ln(N) = ln(N0) - hg

It is evident that:
ln(N) ∝ -g
Thus, we can plot a straight line of ln(N) against -g, with gradient h and y-intercept ln(N0), allowing to easily determine those values if necessary.
0
X

new posts Back
to top
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### University open days

• Sheffield Hallam University
Get into Teaching in South Yorkshire Undergraduate
Wed, 26 Feb '20
• The University of Law
Solicitor Series: Assessing Trainee Skills – LPC, GDL and MA Law - London Moorgate campus Postgraduate
Wed, 26 Feb '20
• University of East Anglia
Sat, 29 Feb '20

### Poll

Join the discussion

Yes (422)
67.41%
No (204)
32.59%