• Support PF! Buy your school textbooks, materials and every day products Here!

Horizontal range questions help

  • Thread starter Sonny18n
  • Start date
  • #1
60
0

Homework Statement


A ball rolls off a table at an initial velocity of 2.5 m/s. The table's height is 3 meters. Similarly another question asks for the same thing except this time it's a rifle shooting a bullet with a velocity of 250 m/s with a height of 3 meters.

Homework Equations


The formula I have is this: sqrt(2*height divided by 9.8)

The Attempt at a Solution


I got the same answer for both because the height is the same but their velocities are radically different. Do they not factor into the formula?
 

Answers and Replies

  • #2
CWatters
Science Advisor
Homework Helper
Gold Member
10,529
2,295
No...because the vertical component is zero in both cases.
 
  • #3
60
0
No...because the vertical component is zero in both cases.
So my answer would be the same for the two questions?
 
  • #4
CWatters
Science Advisor
Homework Helper
Gold Member
10,529
2,295
Probably, but you don't actually state the full question. Are they asking about the velocity the ball hits the ground? The time taken to hit the ground? How high it bounces? Sure I could work it out from the equation you use but how can I tell if you are using the right equation?

Do you understand why you are using that equation and not one that includes the horizontal velocity? Many of the equations of motion include the initial velocity. What is the relevant initial velocity in this case?

Edit: I might be totally wrong. The question title talks about horizontal range? Is that what the question asks you to calculate?

Edit 2: sqrt(2*height divided by 9.8) = ???
 
  • #5
CWatters
Science Advisor
Homework Helper
Gold Member
10,529
2,295
Perhaps I'm being too cryptic.

You quote the equation "sqrt(2*height divided by 9.8)". What does that give you?
 
  • #6
60
0
Probably, but you don't actually state the full question. Are they asking about the velocity the ball hits the ground? The time taken to hit the ground? How high it bounces? Sure I could work it out from the equation you use but how can I tell if you are using the right equation?

Do you understand why you are using that equation and not one that includes the horizontal velocity? Many of the equations of motion include the initial velocity. What is the relevant initial velocity in this case?

Edit: I might be totally wrong. The question title talks about horizontal range? Is that what the question asks you to calculate?

Edit 2: sqrt(2*height divided by 9.8) = ???
Yeah, I'm looking for the horizontal range and how long it spends in the air. I have .78 as the answers. That would mean the horizontal range is 1.56, right?
 
  • #7
CWatters
Science Advisor
Homework Helper
Gold Member
10,529
2,295
Sorry to sound picky but I assume you mean 0.78 seconds? If so then yes that's correct. for both.

Which one (ball or bullet) has a range of 1.56 kilometres?
 

Related Threads on Horizontal range questions help

  • Last Post
Replies
3
Views
774
  • Last Post
Replies
4
Views
3K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
1
Views
8K
Replies
3
Views
17K
Replies
1
Views
1K
Replies
10
Views
1K
Replies
1
Views
698
Replies
3
Views
9K
Top