Determine mass of a glider on an air track

  • Thread starter idlackage
  • Start date
  • #1
11
0
Determine mass of a glider on an air track [solved]

Homework Statement



A 20.0 g mass is stringed to a glider on an air track through a pulley (https://www.physicsforums.com/attachment.php?attachmentid=30478&stc=1&d=1291794499"). I'm supposed to find the mass of said glider, assuming that the air track and pulley are frictionless and the string is massless.

Data from a graph:

V1 = 0.143 m/s
V2 = 0.377 m/s
Δt = 0.24 s

Homework Equations


a = (V2 – V1) / Δt
Fnet = ma

The Attempt at a Solution



a = (V2 – V1) / Δt
= (0.377 – 0.143) / 0.24
= 0.975 m/s2

Mass 1 (https://www.physicsforums.com/attachment.php?attachmentid=30479&stc=1&d=1291794499"):

Fnet = ma
Fn1 + Fg1 + T1 = -m1a
-m1g + T1 = -m1a
-9.8m1 + T1 = -0.975m1
+T = 8.825m1

Mass 2 (https://www.physicsforums.com/attachment.php?attachmentid=30480&stc=1&d=1291794499"):

Fg2 + T2 = m2a
+m2g – T2 = +m2a
(20.0)(9.80) – T2 = 20.0(0.975)
196 – T2 = 19.5
-T2 = -176.5

Final Calculations:

+ T = 8.825m1
(+) – T = -179.84
---------------------
0 = 8.825m1 – 179.84
8.825m1 = 179.84
m1 = 179.84/8.825
= 20 g

When the glider was weighted on a scale, it was said to be 429 g. So I have no idea what I'm doing wrong--am I getting the mass of the "20.0 g mass" here, or is this number just coincidental and irrelevant? Are the equations used incorrect? Thanks for any help.
 
Last edited by a moderator:

Answers and Replies

  • #2
16
0
Last edited by a moderator:
  • #3
23
0
The tensions are equal
 
  • #4
11
0
You do not have to add in Fn1 and Fg1 because they cancel each other out + they are in the vertical direction. You only need to take into account the horizontal forces(which in this case is the tension from the string).

It works now, thank you so much!
 

Related Threads on Determine mass of a glider on an air track

  • Last Post
Replies
8
Views
11K
  • Last Post
Replies
6
Views
6K
  • Last Post
Replies
1
Views
3K
Replies
3
Views
4K
  • Last Post
Replies
1
Views
9K
Replies
18
Views
4K
Replies
8
Views
13K
Replies
14
Views
3K
  • Last Post
Replies
7
Views
8K
  • Last Post
Replies
5
Views
1K
Top