I am having some difficulty answering a few problems on my physics homework.(adsbygoogle = window.adsbygoogle || []).push({});

I don't think that I am coming up with the right equations for given situations in the problems. The questions are as follows:

1. http://herograw.com/8-31.JPG [Broken]

For this question I am getting [tex]- \frac{1}{2} m_1v^2 - \frac{1}{2} m_1v^2+m_2g\Delta h=-m_1\mu_kd[/tex] where m_{1}is the block in contact with the surface and m_{2}is the hanging sphere. When I solve the equation for v (velocity), I getv=4.77 m/s. However, I should be getting a result of3.74 m/s.

2. http://herograw.com/8-48.JPG [Broken]

For this equation I get [tex]mgy_{max}-mgh=-mg \mu_k d[/tex] but there needs to be something with the angle to derive that equation given in the problem.

3. http://herograw.com/8-60.JPG [Broken]

http://herograw.com/figure8.60.JPG [Broken]

When doing part (a) I was using the equation [tex]\frac{1}{2} m v^2+\frac{1}{2} k d^2=0[/tex]to find d. I gotd=0.424 mbut for part (b) I would just get v=3 m/s which is given in the question when the object is moving to the right. I'm not sure if this is right or if I'm approaching the question correctly.

4. http://herograw.com/8-72.JPG [Broken]

For this question I was able to find part (b) but I'm not sure how to start in finding part (a).

Any Help is greatly appreciated.

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Energy Problems (Help Greatly Needed!)

**Physics Forums | Science Articles, Homework Help, Discussion**