The free-body diagram that best represents the forces acting on the student at rest on the
A) 1 B) 2 C) 3 D) 4 E) 5
2. A block of mass M is sliding down a rough inclined surface that makes an angle ？ with
and kinetic friction ；, then respect to the horizontal. If the coefficient of static friction is ；sk
the acceleration of the block down the incline is equal to:
A) gsin ？ ; g ； ？ cos ？ D) gsin ？ ; g ； ？ cos ？ sk
B) gcos？ ; g ； ？ cos ？ E) gsin ？ ; g ； ？ cos ？ ; g ； ？ cos ？ ksk
C) g ； ？ cos ？ ; gsin ？ s
3. When a particle moves in a circle with constant speed, its acceleration is
A) constantly increasing. D) constant in magnitude.
B) constant in direction. E) constant in magnitude and direction.
4. An object traveling in a circle at constant speed
A) is moving with constant velocity.
B) may be slowing down or picking up speed.
C) experiences no acceleration.
D) experiences an acceleration toward the center of the circle.
E) is described by none of the above statements.
5. A car going around a curve of radius R at a speed V experiences a centripetal acceleration
a. What is its acceleration if it goes around a curve of radius 3R at a speed of 2V? c
A) (2/3)a B) (4/3)a C) (2/9)a D) (9/2)a E) (3/2)ac c c c c
6. A car experiences both a centripetal and a tangential acceleration. For which of the
following would this be true?
A) It is going around a curve at a constant speed.
B) It is going around a curve and slowing down.
C) It is going along a straight road at a constant speed.
D) It is going along a straight road and increasing its speed.
E) It is going along a straight road and decreasing its speed.
The figure shows a top view of a ball on the end of a string traveling counterclockwise in a
circular path. The speed of the ball is constant. If the string should break at the instant
shown, the path that the ball would follow is
A) 1 B) 2 C) 3 D) 4 E) impossible to tell from the given information.
8. In the equation F = bv, F is the force on an object that is moving in a viscous medium, b is
a constant, and v is the speed of the falling object. The SI units of the constant b are
2 A) m/s B) kg ? s C) kg/s D) kg ? m E) m/s
9. As a sky diver falls through the air, her terminal speed
A) depends on her mass.
B) depends on her body's orientation.
C) depends on the local value of the acceleration due to gravity.
D) depends on the density of the air.
E) is described by all of the above.