Given values are:
Diameter of base of cup(D1) = 5.0 cm
radius of base of cup(r1) = 5.0 /2 = 2.5 cm
Diameter of mouth of cup(D2) = 8.4 cm
radius of mouth of cup(r2) = 8.4 /2 = 4.2 cm
When cup rolls on top of the table angular speed of mouth(w1 )and base(w2) are equal
w1 = w2
v1 / r1 = v2 / r2 (from the relation of linear velocity and angular velocity v = r w )
v2 / v1 = r2 /r1
v2 = ( r2 /r1 ) * v1 eq(1)
here v1 and v2 are linear velocities of base of cup and mouth of cup
put the values of r1 and r2 in eq(1)
v2 = (4.2 / 2.5 ) * v1
v2 = 1.68 v1
Hence Mouth of Cup rolls 1.68 times faster than base of the cup
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