Circular motion question help please

[helai.j]

no matter how much i understand and study for it i always get stuck in these nasty Questions !  so please help  i wanna know wth am doing wrong

Q1) A circular space station of radius 1000m is designed to rotate about an axis through its center to stimulate gravity. How many revolutions per minute must it perform in order to produce artificial gravity of 9.80-2 ?

Q2) Communication satellites orbit above the equator  in orbits of radius4.24x107m with a period of 24 hours. Calculate the angular velocity of communication satellite and the centripetal acceleration that it experiences .

Q3)  a ceiling fan is turning at a rate of 100 revolutions per minute A spider is clinging to a blade of the fan. if the spider experiences centripetal acceleration greater than 0.3g . it will lose its grip on the blade and be flung off. how far from the center of the fan can the spider safely go.

[S.M.A.T]

no matter how much i understand and study for it i always get stuck in these nasty Questions !  so please help  i wanna know wth am doing wrong

Q1) A circular space station of radius 1000m is designed to rotate about an axis through its center to stimulate gravity. How many revolutions per minute must it perform in order to produce artificial gravity of 9.80-2 ?

Q2) Communication satellites orbit above the equator  in orbits of radius4.24x107m with a period of 24 hours. Calculate the angular velocity of communication satellite and the centripetal acceleration that it experiences .

Q3)  a ceiling fan is turning at a rate of 100 revolutions per minute A spider is clinging to a blade of the fan. if the spider experiences centripetal acceleration greater than 0.3g . it will lose its grip on the blade and be flung off. how far from the center of the fan can the spider safely go.

Don't worry there are some wrong answer in the edexcel a2 revision guide 
By the way here is your solution

[helai.j]

Thanks Alot this is great relief i was doing it right all this time except the first one i didn't know i had to use the 9.80 as acceleration.
i really really appreciate you telling me this thank you a lot .


god bless you

[S.M.A.T]

You welcome

[winnie101]

could u plz explain how  got angular velocity, i dont get it

[Deadly_king]

could u plz explain how  got angular velocity, i dont get it

a = R

where a = acceleration due to gravity ( for this question)
R = radius

Hence = (a/R)^1/2

[winnie101]

ya i got that but i dont get how for ques 3 u got w=(100*2pi)/60
plz explain Thanks

[Deadly_king]

ya i got that but i dont get how for ques 3 u got w=(100*2pi)/60
plz explain Thanks

Hmm........am getting another answer. I think we need to wait for Asif to clarify his method. But am pretty sure he missed something there

w = 2pie/T

T represents the period.

It has been given that the ceiling fan is turning at a rate of 100 revolutions per minute.
This implies that 100 revolutions in 60s.

The period is therefore 100/60

Hence w = 2pie/(100/60) 

[cooldude]

Hmm........am getting another answer. I think we need to wait for Asif to clarify his method. But am pretty sure he missed something there

w = 2pie/T

T represents the period.

It has been given that the ceiling fan is turning at a rate of 100 revolutions per minute.
This implies that 100 revolutions in 60s.

The period is therefore 100/60

Hence w = 2pie/(100/60)  

asif's right,
let a=theta
w=da/dt
da is the change in the angle so 100 revolutions are 100*2pi radians (the change in the angle), and 1 min=60 sec
therefore w=200pi/60=10.5 rad/s

[Deadly_king]

asif's right,
let a=theta
w=da/dt
da is the change in the angle so 100 revolution is 100*2pi radians (the change in angle), and 1 min=60 sec
therefore w=200pi/60=10.5 rad/s
i

Ooh.........I get it dude

Thanks for your help

+rep

[notReverend]

i'm a "bit" late, but
THANKS SO MUCH GUYS!
i was smiling the whole time i did these sums thanks to this very page

[dk bose]

I have got a physics doubt.its 4m Edexcel A2 physics students buk.page no 35,exam zone: topic 1,Question no 5.the question is as follows-
palaeontologists are able to deduce much about the behaviour of dinosaurs from the study of fossilised footprints.The tracks in the attachment show the path of a Tyrannosaurus rex as it attacks a stationary Triceratops.The time between the footprints is 0.62s.(a)Show that the maximum speed of the Tyrannosaurus rex is about 10m/s.(b)the tyrannasaurus rex has a mass of 7000kg.calculate the momentuemjust before it hits the triceratops.(c)Triceratopshas a mass of 5000kg.calculate their combined speed immediately after the collision.(d)The skull of tyrannosaurus rex is heavily reinforced to withstand the force produced in such a collision.Calculate the force exerted on the Tyrannosaurus rex if the time taken to reach their combined speed after the collision is 0.30s.