My guess would be because the gravity from the Earth's core is constantly pulling the ball towards the ground. It's like the moon. Why doesn't the moon just float away in space? Because Earth's gravitational pull keeps it rotating around it. Therefore, the ball will always be pulled towards the core which keeps it from from rolling forever due to friction. But i may be wrong, even though this a quite a good answer, hope it is right!
Answer:
(a) The constants required describing the rod's density are B=2.6 and C=1.325.
(b) The mass of the road can be found using 
Explanation:
(a) Since the density variation is linear and the coordinate x begins at the low-density end of the rod, we have a density given by

recalling that the coordinate x is measured in centimeters.
(b) The mass of the rod can be found by having into account the density, which is x-dependent, and the volume differential for the rod:
,
hence, the mass of the rod is 126.6 g.
Answer:
W = 14523.6 J
Explanation:
Given,
Mass = 3.9 Kg
Vertical height , h = 380 m
Work done against gravitational force
W = m g h
g is acceleration due to gravity
W = 3.9 x 9.8 x 380
W = 14523.6 J
Hence, the work done by the gravitational force is equal to W = 14523.6 J
Answer:
a large matters of body with no shape is mass
Answer:
The coefficient of static friction between the coin and the turntable is 0.51
Explanation:
at the time of the slip:
centripetal force = frictional force
mv^2/r = x*m*980
v^2/r = 980x
x = v^2/980r
= [(120)^2]/[980*29]
= 0.51
Therefore, The coefficient of static friction between the coin and the turntable is 0.51