help physics unit 4

http://store.aqa.org.uk/qual/gceasa/qp-ms/AQA-PA04B-W-QP-JUN06.PDF
question 4 c ii
w=v/r
so v= w x r
r is given as 64 mm so that 0.064 m
and found w as 100.5
v= 100.5 x 0.064 = 6.432 m/s
but the marking scheme says its 3.2 m/s and halfed 64 for the radius
why the f#ck did they do that?? :confused:

http://store.aqa.org.uk/qual/gceasa/qp-ms/AQA-PA04-W-MS-JUN06.PDF

Reply 1

michaelyus

10

MR.PINK

http://store.aqa.org.uk/qual/gceasa/qp-ms/AQA-PA04B-W-QP-JUN06.PDF
question 4 c ii
w=v/r
so v= w x r
r is given as 64 mm so that 0.064 m
and found w as 100.5
v= 100.5 x 0.064 = 6.432 m/s
but the marking scheme says its 3.2 m/s and halfed 64 for the radius
why the f#ck did they do that?? :confused:

http://store.aqa.org.uk/qual/gceasa/qp-ms/AQA-PA04-W-MS-JUN06.PDF

Because the M bit is halfway along the disc, so its orbit's radius is half the disc radius.