Physics I Final - Conceptual Questions
B
A cart moving at speed v collides with an identical stationary cart on an air track, and the two stick together after the collision. What is their velocity after colliding? A) v B) ¹/₂ v C) zero D) -¹/₂ v E) -v F) none of the above
C
A constant force is exerted for a short time interval on a cart that is initially at rest on an air track. This force gives the cart a certain final speed. The same force is exerted for the same length of time on another cart, also initially at rest, which has twice the mass of the first one. The final speed of the heavier cart is ____ that of the lighter cart. A) one-fourth B) four times C) half D) double E) the same as
A
Consider a person standing in an elevator that is accelerating upward. The upward normal force exerted by the elevator floor on the person is ____ the downward weight of the person. A) large than B) identical to C) smaller than
C
Of the arrangements shown, which is the most effective and which is the least effective for loosening the nut? Assume the applied force is the same in each case. A) 1,2 B) 3,4 C) 2,3 D) 4,1
B
On a horizontal tabletop is a curved barrier that exerts a force on a ball, guiding its motion in a circular path as show at right. After the ball leave the barrier, which of the dashed paths shown does it follow? A) path a B) path b C) path c D) Not enough information is given to determine.
E
Compared with the kinetic energy of its center of mass (CM), the total kinetic energy of system ____. A) always less than the kinetic energy of the CM B) always equal to the kinetic energy of the CM C) always greater than the kinetic energy of the CM D) less than or equal to the kinetic energy of the CM E) greater than or equal to the kinetic energy of the CM F) depends on the particular system
B
Consider a car at rest. We can conclude that the downward gravitational pull of Earth on the car and the upward contact force of Earth on it are equal and opposite because: A) the two forces form an action-reaction pair. B) the net force on the car is zero. C) neither of the above
B
Consider a horse pulling a buggy. Is the following statement true? The weight of the horse and the normal force exerted by the ground on the horse constitute an action-reaction pair that are always equal and opposite according to Newton's third law. A) Yes B) No
B
A car rounds a curve while maintaining a constant speed. Is there a net force on the car as it rounds the curve? A) No--its speed is constant. B) Yes. C) It depends on the sharpness of the curve and the speed of the car.
B
A constant force is exerted on a cart that is initially at rest on an air track. Friction between the cart and the track is negligible. The force acts for a short time interval and gives the cart a certain final speed. To reach the same final speed with a force that is only half as big, the force must be exerted on the cart for a time interval ____ that for the stronger force. A) four times as long as B) twice as long as C) equal to D) half as long as E) a quarter of
B
A ladybug sits at the outer edge of a merry-go-round that is turning and slowing down. At the instant shown in the figure, the radial component of the ladybug (Cartesian) acceleration is ____. A) in the +x direction B) in the -x direction C) in the +y direction D) in the -y direction E) in the +z direction F) in the -z direction G) zero
D
A ladybug sits at the outer edge of a merry-go-round that is turning and slowing down. At the instant shown in the figure, the tangential component of the ladybug's (Cartesian) acceleration is ____. A) in the +x direction B) in the -x direction C) in the +y direction D) in the -y direction E) in the +z direction F) in the -z direction G) zero
B
A mailbag is dropped from a plane that is flying at a constant velocity. Which of the following statements is correct? A) The mailbag will quickly lag behind the plane. B) The mailbag will remain vertically under the plane. C) The mailbag will move ahead of the plane. D) There is not enough information given to determine what the mailbag will do.
E
A maximum in a potential energy curve represents a point of ____ equilibrium. A) positive B) negative C) neutral D) stable E) unstable
2
A person initially at point P stays there a moment and then moves along the axis to Q and stays there a moment. She then runs quickly to R, stays there a moment, and then strolls slowly back to P. Which of the position vs. time graphs correctly represents this motion? 1, 2, 3, 4, 5, or 6
A
A rider in a "barrel of fun" finds herself stuck with her back to the wall. Which diagram correctly shows the forces acting on her? A, B, C, D, E, or AB
C
A sports car and a semi-truck collide. The magnitude of the collision force experienced by the truck is ____ the magnitude of the collision force experienced by the car. A) greater than B) less than C) the same as D) Not enough information is given to determine.
B
A sports car and a semi-truck collide. The magnitude of the truck's acceleration is ____ the magnitude of the car's acceleration. A) greater than B) less than C) the same as D) Not enough information is given to determine.
A
A spring-loaded toy dart gun is used to shoot a dart straight up in the air. If the spring is compressed only half as far before firing the same dart straight up again, the dart goes ____ as high as it did the first time. Ignore air resistance. A) 1/4 B) 1/2 C) equally D) 2 times E) 4 times F) not enough information to determine
B
A train car moves along a long straight track. The graph shows the position as a function of time for this train. The graph shows that the train ____. A) speeds up all the time B) slows down all the time C) speeds up part of the time & slows down part of the time D) moves at a constant velocity
A
A whiffle ball is launched straight into the air. In addition to the force of gravity, a frictional force due to air resistance also acts on the ball. When the ball returns to its original position, its speed is ____ its launch speed. A) less than B) equal to C) greater than D) Not enough information to determine
C
An astronaut floating weightlessly in orbit shakes a large iron anvil rapidly back and forth. She reports back to Earth that ____. A) the shaking costs her no effort because the anvil has no inertial mass in space B) the shaking costs her some effort but considerably less than on Earth C) although weightless, the inertial mass of the anvil is the same as on Earth
D
An ice skater spins about a vertical axis through her body with her arms held out. As she draws her arms in, her moment of inertia ____ and her angular velocity ____. A) increases; increases B) decreases; decreases C) increases; decreases D) decreases; increases E) none of the above
D
An object goes from one point in space to another. After it arrives at its destination, its displacement is ____ than the distance it traveled. A) either greater than or equal to B) always greater than C) always equal to D) either smaller than or equal to E) always smaller than
C
An object is held in place by friction on an inclined surface. The angle of inclination is increased until the object starts moving. If the surface is kept at this angle, the object A) slows down. B) moves at uniform speed. C) speeds up. D) none of the above
E
Does the centripetal force acting on an object in uniform circular motion do work on the object? A) Yes, because a force acts and the object moves, and work is force times distance. B) Yes, because it takes energy to turn an object, and work is a transfer of energy. C) No, because the object has constant speed. D) No, because the object's displacement is zero. E) No, because the force and the displacement of the object are perpendicular.
G
Energy is conserved for the following type(s) of collision(s): A) perfectly inelastic B) inelastic C) elastic D) A and B E) A and C F) B and C G) A, B, and C H) none of the above
B
If an object moves with constant speed in a straight line, which of the following statements is true? A) There are no forces acting on the object. B) The net force on the object is zero. C) There is a constant force in the direction of motion. D) There is a constant force in the direction opposite of motion
B
If you drop an object in the absence of air resistance, it accelerates downward at 9.8 m/s². If instead you throw it downward, its downward acceleration after release is ____. A) less than 9.8 m/s² B) 9.8 m/s² C) more than 9.8 m/s²
C
Is it possible for a system to have negative potential energy? A) Yes, as long as the kinetic energy is positive B) Yes, as long as the total energy is positive. C) Yes, since the choice of the zero point for the potential energy is arbitrary. D) No, because the kinetic energy of a system must equal its potential energy. E) No, because this would have no physical meaning.
A
Is it possible for an object's instantaneous velocity and instantaneous acceleration to be of opposite sign at some instant of time? A) yes B) no C) not enough information given
C
Kinetic energy is conserved for the following type(s) of collision(s): A) perfectly inelastic B) inelastic C) elastic D) A and B E) A and C F) B and C G) A, B, and C H) none of the above
G
Momentum is conserved for the following type(s) of collision(s): A) perfectly inelastic B) inelastic C) elastic D) A and B E) A and C F) B and C G) A, B, and C H) none of the above
B
Standing on a roof, you simultaneously throw a ball straight up and drop another from rest. Neglecting air resistance, which ball hits the ground with greater speed? A) the ball dropped from rest B) the ball thrown straight up C) both balls have the same speed D) not enough information given
C
Standing on a roof, you simultaneously throw one ball straight up and another ball down with the same initial speed. Neglecting air resistance, which ball hits the ground with greater speed? A) the ball dropped from rest B) the ball thrown straight up C) both balls have the same speed D) not enough information given
C
The graph shows position as a function of time for two trains running on parallel tracks. Which is true? A) At the time tB, both trains have the same velocity. B) Both trains speed up all the time. C) Both trains have the same velocity at some time before tB. D) Somewhere on the graph, both trains have the same acceleration.
D
The slope of the curve in the position vs. time graph for a particle's motions gives ____. A) the particle's speed B) the particle's acceleration C) the particle's average velocity D) the particle's instantaneous velocity E) not enough information given
C
Three forces have magnitude (in N) that are equal to these quantities: F₁ = x²; F₂ = x; F₃ = x^(¹/₂). Each force acts on an object as it moves from x = 0 to x = 1 m. Which force does the most work? A) F₁ B) F₂ C) F₃ D) not enough information to determine
B
What is the direction of an object's angular momentum vector if the radius vector lies along the x-axis and the velocity vector bisects the +x-axis and the -y-axis? A) +z-axis B) -z-axis C) Counterclockwise D) Clockwise
A
What type of quantity does a kilowatt-hour measure? A) energy B) energy per unit time C) power D) power per unit time E) none of the above
C
Which statement is true about the total mechanical energy of a system? A) it is always positive. B) it is always constant. C) It is constant if acted upon by a conservative force. D) It is constant if acted upon by a non-conservative force. E) It is equally divided between its kinetic energy and potential energy.
B
You are a passenger in a car and not wearing your seat belt. Without increasing or decreasing its speed, the car makes a sharp left turn, and you find yourself colliding with the right-hand door. Which is the correct analysis of the situation? A) Before and after the collision, there is a rightward force pushing you into the door. B) Starting at the time of collision, the door exerts a leeward force on you. C) both of the above D) neither of the above
C
You are throwing a ball straight up in the air. At the highest point, the ball's ____. A) velocity and acceleration are zero B) velocity is nonzero but its acceleration is zero C) acceleration is nonzero but its velocity is zero D) velocity and acceleration are both nonzero