open query 22

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course phy 201

Your solution, attempt at solution. If you are unable to attempt a solution, give a phrase-by-phrase interpretation of the problem along with a statement of what you do or do not understand about it. This response should be given, based on the work you did in completing the assignment, before you look at the given solution.

022. `query 22

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Question: `qQuery gen phy 7.19 95 kg fullback 4 m/s east stopped in .75 s by tackler due west

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Your solution:

95 kg

4m/s east

.75 s west

fnet= ma = 95 kg x 4m/s = 380 kg m/s

4 m/s x .75s = 3 m =

final velocity - 0 m/s

vf = v0 + 2adt

confidence rating #$&*:

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Given Solution:

`a** We'll take East to be the positive direction.

The original magnitude and direction of the momentum of the fullback is

p = m * v1 = 115kg (4m/s) = 380 kg m/s. Since velocity is in the positive x direction the momentum is in the positive x direction, i.e., East.

The magnitude and direction of the impulse exerted on the fullback will therefore be

impulse = change in momentum or

impulse = pFinal - pInitial = 0 kg m/s - 380 kg m/s = -380 kg m/s.

Impulse is negative so the direction is in the negative x direction, i.e., West.

Impulse = Fave * `dt so Fave = impulse / `dt. Thus the average force exerted on the fullback is

Fave = 'dp / 'dt = -380 kg m/s /(.75s) = -506 N

The direction is in the negative x direction, i.e., West.

The force exerted on the tackler is equal and opposite to the force exerted on the fullback. The force on the tackler is therefore + 506 N.

The positive force is consistent with the fact that the tackler's momentum change in positive (starts with negative, i.e., Westward, momentum and ends up with momentum 0).

The impulse on the tackler is to the East. **

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Self-critique (if necessary):

wow I was totally wrong I need practice

where do you get 115 kg

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Self-critique Rating: 2

@& The fullback appears to have lost weight from one edition of the text to the next. The solution didn't pick up the change.

The given solution can be easily adapted to the 95 kg mass.*@

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Self-critique (if necessary):

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Self-critique rating:

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Self-critique (if necessary):

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Self-critique rating:

#*&!

&#Your work looks good. See my notes. Let me know if you have any questions. &#