Physics help please

[only75def]

My physics class has been fairly hard and most people have been failing his tests
He decided to give a take home test to boost everyone's grades hopefully back to Cs/Bs

I finished taking the test (~15 questions) but would like to know if i could send it to someone to check over it and help me out on 3 of them that I am not sure of.

Thank-you so much for any help!

 

[Heads447]

Send em' over

 

I can help you with these pm me the questions

 

[only75def]

Sent to both of you. I'm not positive on #4 and #5.
Also if anyone else sees this I'd love if anyone else could check these 2 questions for me. I can pm them to anyone.

Thank-you very much entrr and heads447

 

[Heads447]

1) .. A -- 0.5*m*r^2 / 4 = (1/8)*mr^2
B.. mr^2
C .. (1/2)*mr^2
D .. (1/12)*m*4r^2 = (1/3) * mr^2

so.. answer is (B)


4) .. time depends only on the factor of radius of gyration which is same even if mass or radius are different...

so... (B) both arrive at same time

5) for same toruqe.. more the distance, less is the force..
so.. teh second force is less..
so.. A) the first force (at midm=pit)


11) inertia of flywheel = 0.5 * 370 * 0.5^2 = 46.25 kg m^2

angular speed = 200 rev / sec = 200 * 2*pi rad/sec = 1256.637 rad/sec

so.. kinetic energy of teh flywheel = =0.5*46.25*1256.637^2 = 36517536.284 J

for maxium speed .. 0.5 * 1500 * v^2 = 36517536.284030626889687616699542
so.. v = 220.6582162 m/sec


12. angular accelerauon = torquw / inertia = 0.85 / 0.1 = 8.5 rad/sec2

13. for torque of all the force about pillar A ..

B*1.6 = 82*9.8*5
so.. B = 2511.25 N upwards...

so.. force by pillar A = 82*9.8 - 2511.25 upwards = - 1707.65 N upwards
or A = 1707.65 N downwards

14. Let the tension in left and righ rope be L and R respectively

for moment of all force about Left rope
R*10 = 100*5 + 400*2
so. R = 130 N
so tention in Right rope = 130 N

so.. L = 100 + 400 - R = 500 - 130 = 370 N
so tentio n in left rope = 370 N

 

[Rockerr]

Send them to me too please if you want