If anyone could help me on a physics question, I would sincerely appreciate it. I have already done it, but somehow I feel it's wrong . If someone could check it and tell me what I'm doing wrong if it is wrong, that would be great!!(adsbygoogle = window.adsbygoogle || []).push({});

1) A 400g object with an initial speed of 80cm/s slides along a horizontal desktop against a frictional force of .7N.

A) How far will it slide before stopping?

B) What is the coefficient of friction between the object and the

table top?

So what I have so far is M=400g, Initial Velocity=80cm/s, Force of kinetic friction is .7N, Final Velocity is 0, and average velocity is 40cm/s. I know I first want to solve for d.

I used F=Ma ( .7N=400g(a) ) and found that acceleration is 1.75m/sec^2

I then used t=V(final)-V(initial)/a to solve for time. I converted my initial velocity into meters/sec. (-.8/1.75= -.4571428571) This makes sense that it's negative since it's deaccelerating.

Then I plugged that inThen I used V(av)=d/t to solve for d. (.4m/s*.4571428571=.1828571429) I dropped the negative b/c distance can't be negative. (Can I do that?) So my answer for A is .182857429m

Now for B I used the equation Mu sub k(coefficient of kinetic friction)=Force of Kinetic friction/Normal Force. So basically, Mu-sub-k=.7/(1.4*9.8) and ended up with .1785714286e-4.

Thank you so much!!!!

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# Homework Help: Drowning in Physics

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