Cutnell/Johnson Physics 8th edition Reading Quiz Questions Classroom Response System Questions Chapter 4 Forces and Newton’s Laws of Motion Reading Quiz Questions

4.1.1. With one exception, each of the following units can be used to express mass. What is the exception? a) newton b) slug c) gram d) N•s2/m e) kilogram

4.1.2. Complete the following statement: The term net force most accurately describes a) the inertia of an object. b) the quantity that causes displacement. c) the quantity that keeps an object moving. d) the mass of an object. e) the quantity that changes the velocity of an object.

4.2.1. Which one of the following terms is used to indicate the natural tendency of an object to remain at rest or in motion at a constant speed along a straight line? a) velocity b) equilibrium c) acceleration d) inertia e) force

4.2.2. Complete the following statement: An inertial reference frame is one in which a) the frame is accelerating. b) Newton’s first law of motion is valid. c) the acceleration due to gravity is greater than zero m/s2. d) Newton’s third law of motion is not valid. e) the inertias of objects within the frame are zero.

4.2.3. Which one of the following statements is true according to Newton’s first law of motion? a) A net force is required to maintain an object at rest. b) A net force is required to maintain an object’s constant velocity. c) A net force is required to change an object’s velocity.

4.2.4. Which one of the following statements concerning Newton’s first law of motion is false? a) If no force acts on an object, the object's velocity cannot change. b) If no net force acts on an object, the object cannot accelerate. c) All objects in motion have forces acting on them. d) All of the answers above are false.

4.3.1. A net force is required to give an object with mass m an acceleration . If a net force is applied to an object with mass 2m, what is the acceleration on this object? a) b) c) d) e)

4.3.2. What unit is defined by a 1-m/s2 acceleration of a 1-kg object? a) Lorenz b) Newton c) Dawson d) Einstein e) Nelson

4.3.3. Complete the following statement: The net force that results when two or more forces act on an object is a) determined by adding the magnitudes of the individual forces. The direction of the net force is the same as the direction of motion. b) the largest force acting on the object. c) determined using vector addition of the individual forces acting on the object. d) the magnitude of the largest force acting on the object. The direction of the net force is the same as the direction of motion.

4.3.4. Which one of the following tools is useful in representing the forces acting on an object and simplifies problem solving? a) free-body diagram b) scalar drawing c) vector analyzer d) Newton’s ladder e) force monitor

4.3.5. Which one of the following equations is associated with Newton's second law? b) c) d) e)

4. 4. 1. An object moves in the eastward direction at constant speed 4.4.1. An object moves in the eastward direction at constant speed. A net force directed northward acts on the object for 5.0 s. At the end of the 5.0-second period, the net force drops to zero newtons. Which one of the following statements is necessarily true? a) The final velocity of the object will be directed north of east. b) The object will be moving eastward when the force drops to zero newtons. c) The direction of the object's acceleration depends on how fast the object was initially moving. d) The change in the velocity of the object will be directed north of west. e) The magnitude of the object's acceleration depends on how fast the object was initially moving.

4. 4. 2. Two forces act on a hockey puck 4.4.2. Two forces act on a hockey puck. For which orientation of the forces will the puck acquire an acceleration with the largest magnitude?

4.5.1. Which one of the following statements is true according to Newton’s third law of motion? a) The vector sum of all forces acting on an object is zero. b) A force on an object produces an equal in magnitude, but oppositely directed force on another object. c) A force on an object produces another equal in magnitude, but oppositely directed force on the object. d) A force on an object produces another differing in magnitude, but oppositely directed force on the object. e) A force on an object produces another differing in magnitude, but oppositely directed force on another object.

4. 5. 2. A cell phone is sitting on a desk 4.5.2. A cell phone is sitting on a desk. Which one of the following is the reaction force to the cell phone’s weight on the desk? a) the gravitational force on the cell phone b) the gravitational force on the table c) the normal force of the Earth on the table d) the normal force of the cell phone on the table e) the normal force of the table on the cell phone

4.6.1. Consider the following forces: (1) frictional, (2) gravitational, (3) tension, (4) strong nuclear, (5) normal, and (6) electroweak. Which of the forces listed are considered fundamental forces? a) 1, 2, and 4 b) 1, 3, and 5 c) 1, 2, 3, and 5 d) 2, 4, and 6 e) 2, 3, 4, and 6

4.7.1. Complete the following statement: Near the surface of the earth, the weight of an object a) is the same as the mass of the object. b) is the gravitational force of the earth on the object. c) has the same value regardless of the altitude above the surface of the earth. d) has the same value regardless of the mass of the object.

4. 7. 2. A rock is thrown straight up from the earth's surface 4.7.2. A rock is thrown straight up from the earth's surface. Which one of the following statements concerning the net force acting on the rock at the top of its path is true? a) It is instantaneously equal to zero newtons. b) It is greater than the weight of the rock. c) It is less than the weight of the rock, but greater than zero newtons. d) Its direction changes from up to down. e) It is equal to the weight of the rock.

4. 7. 3. Two objects with masses m and M are separated by a distance d 4.7.3. Two objects with masses m and M are separated by a distance d. If the distance between the objects is increased to 4d, how does the gravitational force between them change? a) The force will be one-half as great. b) The force will be one-forth as great. c) The force will be one-sixteenth as great. d) The force will be four times as great. e) The force will be sixteen times as great.

4. 7. 4. Two objects with masses m and M are separated by a distance d 4.7.4. Two objects with masses m and M are separated by a distance d. If the separation d remains fixed and the masses of the objects are increased to the values 3m and 3M respectively, how does the gravitational force between them change? a) The force will be nine times as great. b) The force will be three times as great. c) The force will be one-third as great. d) The force will be one-ninth as great. e) It is impossible to determine without knowing the numerical values of m, M, and d.

4.7.5. Which one of the following statements concerning the two "gravitational constants" G, the universal gravitational constant, and g the magnitude of the acceleration due to gravity is true? a) The values of g and G depend on location. b) The values of g and G do not depend on location. c) The value of g is the same everywhere in the universe, but the value of G is not. d) The values of g and G are equal on the surface of any planet, but in general, vary with location in the universe. e) The value of G is the same everywhere in the universe, but the value of g is not.

4.7.6. Which one of the following statements best explains why the weight of an object of mass m is different on Mars than it is on the Earth? a) The mass of Mars is different from that of Earth. b) The object is further from the Earth's center when it is on Mars. c) The mass and radius of Mars are both less than those of Earth. d) The object’s mass will be different on Mars. e) The constant G is different on Mars.

4. 7. 7. Ryan walked to a cliff and dropped a stone 4.7.7. Ryan walked to a cliff and dropped a stone. Neglecting any effects due to the air as it falls vertically, which one of the following is the reaction force to the Earth’s gravity on the stone? a) the normal force of the ground below b) the normal force of Ryan’s hand on the stone c) the gravitational force of the stone acting on the Earth d) No reaction force appears in this situation since the stone is not exerting any forces on anything else.

4.8.1. Note the following situations: In which case will the magnitude of the normal force on the block be equal to (Mg + F sin )? a) case 1 only b) case 2 only c) both cases 1 and 2 d) both cases 2 and 3 e) cases 1, 2, and 3

4.8.2. The magnitude of the apparent weight of an object is the same as which if the following quantities? a) FN, the magnitude of the normal force acting on the object b) the net force acting on the object c) mg, the object’s mass times the acceleration due to gravity d) W  FN, the weight of the object minus the normal force e) ma, the object’s mass times its acceleration

4.8.3. What is the meaning of the word “normal” in the term “normal force?” a) that it is in magnitude and opposite in direction to the weight of the object b) that it is one that is encountered in everyday life c) that it is directed perpendicular to a surface d) that it is measurable e) that it has a magnitude of 1 newton

4. 8. 4. A brick is resting on the surface of a flat board 4.8.4. A brick is resting on the surface of a flat board. As one end of the board is slowly raised, what change, if any, is there in the normal force exerted on the brick? a) The normal force increases. b) The normal force decreases. c) The normal force remains constant. d) Only the direction of the normal force changes.

4.9.1. Which one of the following statements concerning static and kinetic frictional forces is correct? a) When an object is stationary, both static and kinetic frictional forces are acting on it. b) When an object is stationary, only the kinetic frictional force acts on it. c) When an object is sliding, only the static frictional force acts on it. d) The static frictional force acts on an object when it is stationary and the kinetic frictional force acts on it when it is sliding. e) Static and kinetic frictional forces act in the same direction as the normal force.

4.9.2. Two identical blocks are pulled along a rough surface as suggested in the figure. Which one of the following statements is false? a) The coefficient of kinetic friction is the same in each case. b) A force of the same magnitude is needed to keep each block moving. c) The normal force exerted on the blocks by the surface is the same for both blocks. d) The magnitude of the force of kinetic friction is greater for the block on the right. e) A force of the same magnitude was required to start each block moving.

4.10.1. A rock is suspended from a string and moves downward at constant speed. Which one of the following statements is true concerning the tension in the string if air resistance is ignored? a) The tension is less than the weight of the rock. b) The tension is equal to the weight of the rock. c) The tension is greater than the weight of the rock. d) The tension points downward. e) The tension is zero newtons.

4.10.2. During gym class, a boy climbs a vertical rope and temporarily stops half way between the floor below and the ceiling above. Consider the following forces: (1) gravity, (2) normal force, (3) friction, and (4) tension. At that moment, ignoring any effects due to the surrounding air, which of these forces are acting on the boy? a) 1, 2, 3, and 4 b) 1, 2, and 3 only c) 1 and 2 only d) 1 and 3 only e) 1 and 4 only

4.11.1. Under what condition(s) will an object be in equilibrium? a) only if it is at rest b) only if it is moving with constant velocity c) only if it is moving with constant acceleration d) if it is either at rest or moving with constant velocity e) if it is either moving with constant velocity or with constant acceleration

4.11.2. A water skier is pulled by a boat traveling with a constant velocity. Which one of the following statements is false concerning this situation? a) The water skier is in equilibrium. b) The net acceleration of the skier is zero m/s2. c) The net force on the skier is zero newtons. d) There is a net horizontal force on the skier in the direction the boat’s velocity. e) The net vertical force on the skier is zero newtons.

4.11.3. A small plane increases its altitude by flying with a constant velocity at an angle  with respect to the horizontal. Which one of the following statements is true concerning the magnitude of the net force on the plane? a) It is equal to the weight of the plane. b) It is equal to the magnitude of the force of air resistance. c) It is equal to zero newtons. d) It is less than the weight of the plane but greater than zero newtons. e) It is equal to the component of the weight of the plane in the direction of motion.

4.12.1. A man stands on a spring scale in a moving elevator and notices that the scale reading is 20% larger than when he weighs himself in his bathroom. Which one of the following statements can not be true? a) The elevator could be moving upward at constant speed. b) The elevator could be moving upward with increasing speed. c) The elevator could be moving downward with decreasing speed. d) The speed of the elevator changes by equal amounts in equal times. e) The tension in the supporting cable must exceed the weight of the elevator and its contents.

4.12.2. A block is pulled at constant speed along a rough level surface by a rope that makes an angle  with respect to the horizontal. The applied force along the rope is P. The force of kinetic friction between the block and the surface is f. Which one of the following actions will increase the frictional force on the block? a) increasing the angle made by the rope b) decreasing the speed of the block c) decreasing the contact surface area d) increasing the contact surface area e) increasing the weight of the block

4.12.3. A smooth wooden block is sitting at rest on a flat wood board that makes an angle  with respect to the horizontal plane. To which of the following parameters is the normal force on the block proportional? a) cos  b) sin  c) tan 