AP phy motion

A ball is thrown downward from the edge of a cliff with an initial speed that is three times the terminal speed. Initially its acceleration is A. upward and greater than g B. upward and less than g C. downward and greater than g D. downward and less than g E. downward and equal to g

A

A ball is thrown upward into the air with a speed that is greater than terminal speed. It lands at the place where it was thrown. During its flight the force of air resistance is the greatest: A. just after it is thrown B. halfway up C. at the top of its trajectory D. halfway down E. just before it lands.

A

A boat is traveling upstream at 14km/h with respect to a river that is flowing at 6 km/h (with respect to the ground). A man runs directly across the boat, from one side to the other, at 6km/h (with respect to the boat). The speed of the man with respect to the ground is: A. 10km/h B. 14km/h C. 18.5km/h D. 21km/h E. 26km/h

A

A car moves horizontally with a constant acceleration of 3m/s2. A ball is suspended by a string from the ceiling of the car. The ball does not swing, being at rest with respect to the car. What angle does the string make with the vertical? A. 17◦ B. 35◦ C. 52◦ D. 73◦ E. Cannot be found without knowing the length of the string

A

A girl wishes to swim across a river to a point directly opposite as shown. She can swim at 2m/s in still water and the river is flowing at 1m/s. At what angle θ with respect to the line joining the starting and finishing points should she swim? A. 30◦ B. 45◦ C. 60◦ D. 63◦ E. 90◦

A

Two blocks with masses m and M are pushed along a horizontal frictionless surface by a horizontal applied force F as shown. The magnitude of the force of either of these blocks on the other is: A. mF/(m +M) B. mF/M C. mF/(M − m) D. MF/(M + m) E. MF/m

A

Which one of the following statements is correct for an object released from rest? A. The average velocity during the first second of time is 4.9m/s B. During each second the object falls 9.8m C. The acceleration changes by 9.8m/s2 every second D. The object falls 9.8m during the first second of time E. The acceleration of the object is proportional to its weight

A

1. An example of an inertial reference frame is: A. any reference frame that is not accelerating B. a frame attached to a particle on which there are no forces C. any reference frame that is at rest D. a reference frame attached to the center of the universe E. a reference frame attached to Earth

B

3. When the brakes of an automobile are applied, the road exerts the greatest retarding force: A. while the wheels are sliding B. just before the wheels start to slide C. when the automobile is going fastest D. when the acceleration is least E. at the instant when the speed begins to change

B

A cannon fires a projectile as shown. The dashed line shows the trajectory in the absence of gravity; points MNOP correspond to the position of the projectile at one second intervals. If g = 10m/s2, the lengths X,Y,Z are: A. 5m, 10m, 15m B. 5m, 20m, 45m C. 10 m, 40 m, 90m D. 10 m, 20 m, 30m E. 0.2m, 0.8m, 1.8m

B

A jet plane in straight horizontal flight passes over your head. When it is directly above you, the sound seems to come from a point behind the plane in a direction 30◦ from the vertical. The speed of the plane is: A. the same as the speed of sound B. half the speed of sound C. three-fifths the speed of sound D. 0.866 times the speed of sound E. twice the speed of sound

B

A motor boat can travel at 10 km/h in still water. A river flows at 5 km/h west. A boater wishes to cross from the south bank to a point directly opposite on the north bank. At what angle must the boat be headed? A. 27◦ E of N B. 30◦ E of N C. 45◦ E of N D. 60◦ E of N E. depends on the width of the river

B

An elevator is moving upward with constant acceleration. The dashed curve shows the position y of the ceiling of the elevator as a function of the time t. At the instant indicated by the dot, a bolt breaks loose and drops from the ceiling. Which curve best represents the position of the bolt as a function of time?

B

Two blocks, weighing 250N and 350 N, respectively, are connected by a string that passes over a massless pulley as shown. The tension in the string is: A. 210N B. 290N C. 410N D. 500N E. 4900N

B

A 1-N pendulum bob is held at an angle θ from the vertical by a 2-N horizontal force F as shown. The tension in the string supporting the pendulum bob (in newtons) is: A. cos θ B. 2/ cos θ C. √5 D. 1 E. none of these

C

A car rounds a 75-m radius curve at a constant speed of 18m/s. A ball is suspended by a string from the ceiling the car and moves with the car. The angle between the string and the vertical is: A. 0 B. 1.4◦ C. 24◦ D. 90◦ E. cannot be found without knowing the mass of the ball

C

A crate resting on a rough horizontal floor is to be moved horizontally. The coefficient of static friction is 0.40. To start the crate moving with the weakest possible applied force, in what direction should the force be applied? A. Horizontal B. 24◦ below the horizontal C. 22◦ above the horizontal D. 24◦ above the horizontal E. 66◦ below the horizontal

C

A short 10-g string is used to pull a 50-g toy across a frictionless horizontal surface. If a 3.0 × 10−2-N force is applied horizontally to the free end, the force of the string on the toy, at the other end, is: A. 0.15N B. 6.0 × 10−3 N C. 2.5 × 10−2 N D. 3.0 × 10−2 N E. 3.5 × 10−2 N

C

A toy racing car moves with constant speed around the circle shown below. When it is at point A its coordinates are x = 0, y = 3m and its velocity is (6m/s)ˆi. When it is at point B its velocity and acceleration are: A. −(6m/s)ˆj and (12m/s2)ˆi, respectively B. (6m/s)ˆi and −(12m/s2)ˆi, respectively C. (6m/s)ˆj and (12m/s2)ˆi, respectively D. (6m/s)ˆi and (2m/s2)ˆj, respectively E. (6m/s)ˆj and 0, respectively

C

An object placed on an equal-arm balance requires 12 kg to balance it. When placed on a spring scale, the scale reads 12 kg. Everything (balance, scale, set of weights and object) is now transported to the Moon where the free-fall acceleration is one-sixth that on Earth. The new readings of the balance and spring scale (respectively) are: A. 12 kg, 12 kg B. 2kg, 2kg C. 12 kg, 2 kg D. 2 kg, 12 kg E. 12 kg, 72 kg

C

Throughout a time interval, while the speed of a particle increases as it moves along the x axis, its velocity and acceleration might be: A. positive and negative, respectively B. negative and positive, respectively C. negative and negative, respectively D. negative and zero, respectively E. positive and zero, respectively

C

A 50-N force is applied to a crate on a horizontal rough floor, causing it to move horizontally. If the coefficient of kinetic friction is 0.50, in what direction should the force be applied to obtain the greatest acceleration? A. Horizontal B. 60◦ above the horizontal C. 30◦ above the horizontal D. 27◦ above the horizontal E. 30◦ below the horizontal

D

A 800-N passenger in a car presses against the car door with a 200N force when the car makes a left turn at 13m/s. The (faulty) door will pop open under a force of 800 N. Of the following, the least speed for which the passenger is thrown out of the car is: A. 14m/s B. 19m/s C. 20m/s D. 26m/s E. 54m/s

D

A circus performer of weight W is walking along a "high wire" as shown. The tension in the wire: A. is approximately W B. is approximately W/2 C. is much less than W D. is much more than W E. depends on whether he stands on one foot or two feet

D

A giant wheel, having a diameter of 40 m, is fitted with a cage and platform on which a man of mass m stands. The wheel is rotated in a vertical plane at such a speed that the force exerted by the man on the platform is equal to his weight when the cage is at X, as shown. The net force on the man at point X is: A. zero B. mg, down C. mg, up D. 2mg, down E. 2mg, up

D

A professor holds an eraser against a vertical chalkboard by pushing horizontally on it. He pushes with a force that is much greater than is required to hold the eraser. The force of friction exerted by the board on the eraser increases if he: A. pushes with slightly greater force B. pushes with slightly less force C. stops pushing D. pushes so his force is slightly downward but has the same magnitude E. pushes so his force is slightly upward but has the same magnitude

D

Two automobiles are 150 kilometers apart and traveling toward each other. One automobile is moving at 60km/h and the other is moving at 40km/h mph. In how many hours will they meet? A. 2.5 B. 2.0 C. 1.75 D. 1.5 E. 1.25

D

A dart is thrown horizontally toward X at 20m/s as shown. It hits Y 0.1 s later. The distance XY is: A. 2m B. 1m C. 0.5m D. 0.1m E. 0.05m

E

A sled is on an icy (frictionless) slope that is 30◦ above the horizontal. When a 40-N force, parallel to the incline and directed up the incline, is applied to the sled, the acceleration of the sled is 2.0m/s2, down the incline. The mass of the sled is: A. 3.8kg B. 4.1kg C. 5.8kg D. 6.2kg E. 10 kg

E

Two objects, one having three times the mass of the other, are dropped from the same height in a vacuum. At the end of their fall, their velocities are equal because: A. anything falling in vacuum has constant velocity B. all objects reach the same terminal velocity C. the acceleration of the larger object is three times greater than that of the smaller object D. the force of gravity is the same for both objects E. none of the above

E