Calculating final velocity after a puck is hit

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Homework Help Overview

The problem involves calculating the final velocity of a puck after being hit by a player, given its mass, initial velocity, force applied, and contact time. The subject area includes concepts from dynamics and impulse-momentum theory.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the initial conditions of the puck and the force applied, questioning the direction of the puck's initial velocity and how it affects the final velocity calculation. There are attempts to apply the impulse-momentum theorem and clarify the relationship between force, mass, and acceleration.

Discussion Status

Some participants have provided guidance on using the impulse-momentum theorem and have prompted the original poster to clarify the quantities involved. There is an acknowledgment of the need to consider vector components in the calculations, but no consensus has been reached on the correct approach or resolution of the problem.

Contextual Notes

There is a noted ambiguity regarding the initial direction of the puck and the implications of applying a force at an angle. Participants are also addressing issues related to unit consistency and vector treatment in the calculations.

kinghunter
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Homework Statement


Bob passes a 0.220kg puck with an initial velocity of 12m/s [South] to Dave. Dave one-times the puck with a force of 368N [N30E] if Daves stick is in contact with the puck for 0.250s what is the final velocity?

Homework Equations


i honestly don't know where to start with this one, if you can tell me what i first need to solve for i should be able to go from there

The Attempt at a Solution

 
Last edited:
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Look in your course notes and/or textbook for "Impulse".

As the question is, it can't be solved, we don't know the initial direction of the puck.
 
billy_joule said:
Look in your course notes and/or textbook for "Impulse".

As the question is, it can't be solved, we don't know the initial direction of the puck.
sorry the initial directon is south
 
kinghunter said:

Homework Statement


Bob passes a 0.220kg puck with an initial velocity of 12m/s [South] to Dave. Dave one-times the puck with a force of 368N [N30E] if Daves stick is in contact with the puck for 0.250s what is the final velocity?

Homework Equations


i honestly don't know where to start with this one, if you can tell me what i first need to solve for i should be able to go from there

The Attempt at a Solution

Hello kinghunter. Welcome to PF !

What quantities are you given? What do you need to find ?

Consider using the Impulse - Momentum Theorem.

You will need to show an attempt before we can give you any more help.
 
i believe the initial velocity when dave hits the puck is 12m/s (carried over from the initial pass), he hits it with a force of 368N [N30E], its in contact with his stick for 0.25s (acceleration period) and the mass of the puck is 0.22kg so what i did is F=ma and a=v/t F=m(vf-vi/t)
vf=F(t)+vi / m
=368N(0.25s)+12m/s / 0.22kg
but then i get an unrealistic number = 472.7m/s
 
kinghunter said:
i believe the initial velocity when dave hits the puck is 12m/s (carried over from the initial pass), he hits it with a force of 368N [N30E], its in contact with his stick for 0.25s (acceleration period) and the mass of the puck is 0.22kg so what i did is F=ma and a=v/t F=m(vf-vi/t)
vf=F(t)+vi / m
=368N(0.25s)+12m/s / 0.22kg
but then i get an unrealistic number = 472.7m/s
For one thing your units are don't work out in several places, partly because you ignore placing parentheses adequately.

Beyond that: Force, velocity and acceleration are all vector quantities. A force in the east - west direction will only cause acceleration in the east - west direction so only changes the component of velocity in the east - west direction. The component of velocity in the north - south direction will remain unchanged at 12 m/s [south] .
 

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