(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A 25 kg box is being pushed across the floor by a constant force ‹ 100, 0, 0 › N. The coefficient of kinetic friction for the table and box is 0.18. At t = 7.0 s the box is at location ‹ 11, 4, −3 › m, traveling with velocity ‹ 6, 0, 0 › m/s. What is its velocity and position at t = 8.5 s?

2. Relevant equations

deltaP= Fnet(deltat)

3. The attempt at a solution

My professor gave us a hint that once we find the the fnet, then we can use the momentum principle and the position update formula to find the velocity and the position. So my problem is how to find the fnet.

The method that I tried to find the fnet is: 100-(25*0.18*9.8)= 55.9

Well, there is another method (25*9.8) + (.18*100) = 263

Is one of them correct? (I can see that the difference between these two numbers are pretty large)

Once I find the fnet, then I can use the momentum principle, which is Pf=Pi + fnet(delta t) to find the final momentum. Then from there, find the final velocity.

Pi = 150

delta t = 8.5-7= 1.5

Thanks in advance for your assistance!

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# Homework Help: Friction problem: finding the Fnet first

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