Mentor's note: this was originally posted in a non-homework forum, so it doesn't have the homework template. ------------------------------------ Hey guys hoping you guys could help me with this A object (20g) moving horizontally at 100m/s embeds itself in the middle of a block of some wood with a mass of 1kg . the block of wood is suspended by a light vertical string of the length 1m. This is the drawing he gave in class (the drawing is not drawn to scale) http://imgur.com/HGuPTL8 Calculate: a)the maximum inclination of the string b)the maximum angle of inclination of the string after the object collides with the wood. So the teacher gave this question as part of the homework, now almost no one in my class has been able to get it so far because i dont think we ever discussed max angles of inclination. But I tried part one at least. First we never were thought about angles of inclination but im just going to assume its the angle of repose. So i figure using the formula angle =archtan(tan inverse) * coefficient of friction. Now there is no mention of coefficient of friction in this so I assumed it had to be calculate. We were never thought this but form the name it implies its a ratio of sin to cos. so because the block was vertically hanged it must be at a 90 degree angle perpendicular to the ground right? so i used 1kgsin90 /1kgcos90 but then i realized its not an inclined plane so then 1kgcos90 would be zero and give me zero as the divisor which cant work. So i just used the sin part which gave me: 1kgsin90 =1 as my coefficient of friction , then using the formula i mentioned before: angle = tan inverse of 1 =45 degrees this makes sense to me because in parabolic motion at least 45 is the angle you throw at to get the furthest distance so 45 makes sense to be the highest angle of inclination. That's what i thought at least. But as I said we ddint go in depth about this at class so what I wrote above could be completely off. Now for b I really didnt have any idea what to do because I wasn't sure is a) was correct. It says whats the max inclination for the object and wood so im guessing you do something similar to a but then instead of 1 kg you add the masses together as 1.02kg , but im not sure where the velocity of the question comes into play. Any help would be appreciated.