Simple average speed/average velocity problem

  • Thread starter Thread starter SoConfused__
  • Start date Start date
  • Tags Tags
    Average Velocity
Click For Summary
Jeremy runs a total distance of 16 km, with an average speed of 16 km/h for the first 8 km and 10 km/h for the return. His total time for the trip is calculated as 1.3 hours, leading to an average speed of approximately 12.3 km/h, which should be rounded to 12 km/h for consistency with the significant figures of the problem. The average velocity, considering he returns to the starting point, is indeed 0, as there is no net displacement. The calculations are confirmed to be correct, and rounding is necessary for accuracy.
SoConfused__
Messages
23
Reaction score
0

Homework Statement


Jeremy is training for a boxing match. He runs due north at an average speed of 16km/h for the first 8.0 km and returns to the training camp at an average speed of 10 km/h. Calculate his average speed and his velocity.


Homework Equations


Vavg = Total Distance / Total Time
Average Velocity = Final displacement / Total time taken


The Attempt at a Solution


16 km/h for first 8.0 km = 0.5 hours
10 km/h for the trip back = 0.8 hours
Total time taken = 1.3 hours
Total distance = 16 km

Average speed = 16/1.3
=12.3 km/h.

The answer on my sheet is 12km/h. Am I doing something wrong or is it just rounded?
For average velocity, would it be 0? Since there is no displacement from the starting point?

I am just starting physics, and I just need guidance in the right direction.

Thank you.
 
Physics news on Phys.org
Your calcs look good. Yes, the answer should be rounded to 2 digits since all the given quantities are accurate to 2 digits.
 
Alright, thank you!
Sorry if this seems like a silly question, I just want to make sure my work is correct before going forward.
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

Similar threads

  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 9 ·
Replies
9
Views
1K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
Replies
5
Views
5K
  • · Replies 13 ·
Replies
13
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K