Bukhovtsev-et-al-Problems-in-Elementary-Physics

MECHANICS
45
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moves with and the angular velocity which the rod rotates with
relative to an axis passing through the centre of gravity.
184. A cannon is at the centre of a platform freely rotating
around a vertical axis. The axis of rotation passes through the
breech of the cannon. A shell is fired in a horizontal direction
along the radius of the platform. Will the velocity of rotation
change in this case?
185. A small body begins to slide without initial velocity
down an inclined plane with a height H (Fig. 73). Assuming
that there is no friction and the impact of the body against
horizontal plane AB is absolutely elastic. determine the nature
of motion of the body after it leaves the inclined plane. Answer
the same question if the impact is absolutely inelastic.
186. What is the minimum radius of an arc that can be negotiated
by a motor-cyclist if his speed is v = 21 mls and the
coefficient of friction between the tyres and the ground k = O.3?
To what angle a to the horizon should the motor-cycle be
inclined in this case?
187. A massive sphere is fitted onto a light rod (Fig. 74).
When will the rod fall faster: if it is placed vertically on
end A or on end B? The end of the rod on the ground does
not slip.
188. A massive sphere is secured on the end of a light rod
placed vertically on a floor. The rod begins to fall without any
initial velocity. At what angle a between the rod and a vertical
will the end of the rod no longer press on the. floor?
At what coefficient of friction will the end of the rod not
slip up to this moment?
t
90
Fig. 72