Okay, So... I'm having trouble understanding what I did wrong here. I can't seem to understand how I got this problem wrong.(adsbygoogle = window.adsbygoogle || []).push({});

Here's the problem statement:

A 0.160-kg hockey puck is moving on an icy, frictionless, horizontal surface. At t=0 the puck is moving to the right at 2.98 m/s.

a.) Calculate the magnitude of the velocity of the puck after a force of 24.9 N directed to the right has been applied for 4.80×10−2 s.

b.) What is the direction of the velocity of the puck after a force of 24.9 N directed to the right has been applied for 4.80×10−2 s.

c.) If instead, a force of 12.2 N directed to the left is applied from t=0 to t= 4.80×10−2 s, what is the magnitude of the final velocity of the puck?

d.) What is the direction of the final velocity of the puck in this case?

So I've got everything right-- except for part c. ...I would imagine that I'd do it the exact same way I did part a. This is what I did for part c:

[tex]J_{x} = impulse[/tex]

[tex]J_{x} = p_{2x} - p_{1x}[/tex]

[tex]J_{x} = F_{x}(t_{2}-t_{2}) = -12.2(.048) = -.5856[/tex]

[tex]p_{2x} = J_{x} + p_{1x} = -.5856 + (.16)(2.98) = -.1088[/tex]

[tex]v_{2x} = \displaystyle{\frac{p_{2x}}{m}} = \displaystyle{\frac{-.1088}{.16}} = -.68[/tex]m/s

Why is this wrong? What did I do wrong?

Thanks!

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# Homework Help: Impulse And Momentum

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