Time Projectile Problem Solved - Thanks!

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    Projectile Time
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Homework Help Overview

The discussion revolves around a projectile motion problem, specifically focusing on determining initial and final velocities, vertical displacement, and the time of flight. Participants are exploring the equations of motion relevant to vertical motion under gravity.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss various equations that may apply to the problem and question which known values can be used in the vertical direction. There is an emphasis on identifying known quantities such as vertical displacement and acceleration due to gravity.

Discussion Status

The discussion is active with participants sharing insights on how to approach the problem. Some have provided guidance on identifying known values and equations, while others express uncertainty about the correct equations to use for finding final velocity and time.

Contextual Notes

Participants note that vertical displacement is 15m and that gravity is -9.8 m/s² when considering upward direction as positive. There is an ongoing exploration of the implications of these values on the calculations needed.

MrRandom66
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Problem solved, many thanks
 
Last edited:
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Write down some equations that may be used. The we can discuss which of them can apply.
 
You might want to check your units.
 
I'm really not sure what equations to use. I have a list of some equations but they ask for the initial velocity.
 
You can find the initial speed in the vertical direction.
 
grzz said:
You can find the initial speed in the vertical direction.

Could you explain that please?
 
Try to find what is known in the vertical direction.
 
grzz said:
Try to find what is known in the vertical direction.

Vertical displacement is 15m, and Gravity due to acceleration is 9.8 m s^2
 
initial speed
final speed
distance travelled
acceleration
time
Which of the above are known in the vertical direction?
 
  • #10
What is the speed in the vertical at the maximum height?
 
  • #11
Distance Travelled, and Acceleration?

Feel like I'm missing something here...
 
  • #12
MrRandom66 said:
Vertical displacement is 15m, and Gravity due to acceleration is 9.8 m s^2
Correct but acceleration is negative if we choose upward direction as positive.
 
  • #13
Oh zero. I was missing something
 
  • #14
Now you CAN find the initial speed in the vertical direction.
 
Last edited:
  • #15
Before I calculate the final speed, I have to get t, correct? So, am I write in believing this is 15m/-9.8 m s^2
 
  • #16
MrRandom66 said:
Before I calculate the final speed, I have to get t, correct?
I think that you mean the initial (vertical) speed.
 
  • #17
grzz said:
I think that you mean the initial (vertical) speed.

Yes, I did.
 
  • #18
If you know the initial and final vertical speeds, and the vertical distance you can find the time which is the quantity that you originally wanted to find.
 
  • #19
grzz said:
If you know the initial and final vertical speeds, and the vertical distance you can find the time which is the quantity that you originally wanted to find.

Sorry, I'm having a hard time getting my head round this.
I'm not sure what equation to use to find final velocity.
 
  • #20
You will only learn how to do physics only if you try to pick the equation yourself.
Try to find - from notes or internet - the equations you can use.
 
  • #21
OK, I've got the equation for final velocity, give me a minute and i'll work out the time.
 
  • #22
Ok, so now I have the time, am I right in believe the total time for the projectile will be the time I've just calculated, x2?
 
  • #23
Yes.
 
  • #24
Brilliant! Thanks, Now I've got to work out the launch speed... :-/

I'm going to double check my notes, but I'm sure i'll need help sooner or later.
 

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