Sarahisme

k thanks

ok sure, i will just write it up now

you mean working?

Hey just wanted to check my answer for this question damn answers in back of book only being for every 2nd question i get v = 1.40m/s well heres the question

i was thinkning about doing this problem using a computer, ie. making a program to do it. but i have limited skills in this area. is there anyone here who could help me with this? Cheers Sarah

k thanks

oh ok thanks

or what kind of physics (sections of classical mechanics) would be useful to solve these kinds of problems?

another general question.... if you have an object in space (ie. a spaceship) and you want it to orbit nearby planets, can you do it by taking the centre of mass of the 2 planets. Cheers guys (i hope this thread is in the right place ) Sarah

i think it may be because that if you set the "zero" position for PE to be at the bottom of the swing, therefore Emech will be just .5mv^2 because PE at this point is zero. so the formula Emech = PE + KE, is just Emech = KE what do you guys think? man bad hangover and not much sleep

hey everyone sorry i just got back from a big night out last night and yeah hard to think, so that sort of explains the title anyways.... my query (this is not a homework question of anything, just a general th0ouoght i had when reading a physics text) why is it that when a pendulum is swinging that you can assume it has maximum KE at the bottom of its swinging arc? Cheers Sarah

oh okies well still thanks for everything

whats this about? Oh thanks a million for helping me swansont

is that right? lol i really hope so this time

oh i see... sorry now that i think about it, so to summarise a) is correct but b) should be 600N, because thats the net force and c) should use 680N because thats the force applied to move the system in b) ?

i am not entirely sure what you mean, sorry :S which part of my answer?

so what do people think? compltely wrong or what?

ok I have completely rethought the problem, ignore my previous answers....ok here goes I’ll try and explain my new answers.... a) what causes the small block to move is the friction between it and the larger block. since the little block is a=4m/s/s, therefore the force required to move it must be F=ma (where m is mass of the little block = 20kg), and so the force required to accelerate an object is 80N. Since the acceleration of the small block is caused by the friction between it and the large one, therefore the frictional force exerted by the 100-kg mass on the 20-kg mass is 80N. b) The net force in the y direction is 0. In the x direction the net force is the force required to accelerate a 100kg mass at 6m/s/s, but by Newton's third law there is a retarding force of 80N (opposite to the frictional force), so the net force in the x direction is F - 80 = 100kg x 6m/s/s which is equal to 680N c) This is I think the easy part. With the same force of 680N what is the acceleration of the 100kg block? well... F=ma 680N = 100kg x a therefore a = 6.8m/s/s So the acceleration after the 20kg mass falls off (assuming that the force F does not change) is 6.8m/s/s

oh btw i just checked out some of your cartoons...lol quantum mechanic hahahaha

i think the fs (static friction) is causing the small lock to acclerate in the forward direction. how about if i upload a picture(s) of my working?

oh ok an answer sorry i got a)-40N b)720N in positive x direction c)7.2m/s/s sorry bout that Sarah

lol anyone? even a comment? like "this is too hard" or "man sarah you are stupid, this question is so easy!" anything at all

Hey i am currently studying for a physics exam and the questions we have been given have answers to only the odd numbered questions. But i like to be throuhgly prepared for exams and so am doing all of them. As you have probably guessed by now i need some help with an even numbered question. I think i have done it, but i am pretty unsure, so i would really really like to check if my answer is correct. I will attach the problem as a picture. Thanks Sarah p.s i wasn't sure whether to post here or in the physics:classical mechanics section of the forums. tell me if i should repost or whatever