Help on a rather simple physics question

  • Thread starter Fullmetalx
  • Start date
  • #1

Homework Statement


Suppose you drop a feather and a steel ball of equal masses (0.014 kg) at the same time from a height of 1.5 m and you are told that the feather hits the floor 3.5 s after the steel ball. Estimate the value of the terminal velocity of the feather in air.

Estimate the feather's drag coefficient.


Homework Equations



v=mg/c

The Attempt at a Solution



I assumed the drag on the steel ball is negligible. So i used r=vit +.5at^2 to find the time it takes for it reach the ground. I then added 3.5s and used another kinematic equation to find the final velocity or terminal velocity. I then plugged the answer into the above equation to find c. it was wrong
 

Answers and Replies

  • #2
Simon Bridge
Science Advisor
Homework Helper
17,857
1,655
What does the v-t graph of the feather look like?
i.e. do the kinematic equations even apply to it's motion?

Consider: if the air-resistance for the steel ball can be neglected - so it never reaches it's terminal velocity - then what is the case for the feather? How long does it take the feather to reach it's terminal velocity?
 
  • #3
21,158
4,672
Assume that the feather reaches its terminal velocity instantaneously. How far did it fall? How many seconds did it take to fall this distance? What was its velocity?
 

Related Threads on Help on a rather simple physics question

Replies
23
Views
2K
  • Last Post
Replies
5
Views
15K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
4
Views
578
Replies
8
Views
2K
  • Last Post
Replies
3
Views
2K
  • Last Post
Replies
1
Views
2K
Replies
1
Views
1K
Replies
4
Views
1K
Replies
1
Views
6K
Top