A
block is at rest on a rough plane inclined at an angle q relative to the horizontal.A
block is at rest on a rough plane inclined at an angle q relative to the horizontal.
The angle is slowly reduced. Which one of the following options correctly describes the changes, if any, in the frictional force F and the coefficient of static friction between the block and the plane?
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Two unequal masses m and M are connected with
light cord over a pulley with negligible mass.
When released the system accelerates.
Ignoring friction which figure at right best shows the correct free body diagrams for the two masses in the moving system?
An amusement
park ride sometimes called 'the fly' is a large cylinder which
can rotate. A person stands against the wall, and after the cylinder
is rotating at a certain rate the floor drops away. The person
remains 'stuck' in position against the wall - like a fly.
Which one of the diagrams at right is the correct free-body force diagram showing all the forces acting on the person when the person is in the position shown above?
Raindrops fall with constant speed during the latter stages
of their descent because....
a ... the gravitational force is the same for all drops.
b ... air resistance just balances the force due to gravity.
c ... the drops all fall from about the same height.
d ...the force of gravity is negligible for objects as small as raindrops.
A
force P directed up a plane, of angle Q to a horizontal, prevents
a block of mass M from sliding down, as shown in the diagram.
If the coefficient of static friction between the block and the plane is m. The minimum magnitude of the force P is
a Mg sinq
b Mg (sinq - m cosq )
c Mg (sinq + m cosq )
d Mg (cosq - m sinq )
A trolley is given an initial force along a floor to get
it moving. The trolley then travels forward along the floor, gradually
slowing. What is true of the horizontal force(s) on the trolley
as it is slowing?
a There is a forward force and a backward force, but the forward force is larger.
b There is a forward force and a backward force, but the backward force is larger.
c There is only a forward force, which diminishes with time.
d There is only a backward force.