2 problems: potential erg & tension/friction

[Falinox]

Homework Statement

http://i754.photobucket.com/albums/xx183/reddiesel08/Question1.jpg

http://i754.photobucket.com/albums/xx183/reddiesel08/Question2.jpg

2. The attempt at a solution

http://i754.photobucket.com/albums/xx183/reddiesel08/Attempt2.jpg

http://i754.photobucket.com/albums/xx183/reddiesel08/Attempt.jpg

Need someone to check my work and help solve these two problems, thanks in advance to anyone willing to help.

 

[rock.freak667]

5 is correct, but I did not check the numbers for this one.

7, your method is correct, but your final answer is off. My calculator gives me v_i = 4.76 m/s

 

[Falinox]

5 is correct, but I did not check the numbers for this one.

7, your method is correct, but your final answer is off. My calculator gives me v_i = 4.76 m/s

Thank you! My mistake on question 7 was I forgot to multiply the 9.8(0.68) by 2 when I moved the 1/2 from the left side to the right side of the equation. I also came up with the answer 4.76 m/s.

On #5 I got the answer a = .57 m/s squared can someone verify this for me.

 

[rock.freak667]

a = 0.56645 m/s^2, so you are correct.