Final exam guide
96)The average braking force of a 1000-kg car moving at 10 m/s braking to a stop in 5 s is A) 1000 N. B) 2000 N. C) 3000 N. D) 4000 N. E) 5000 N.
Answer: B) 2000 N.
43)Nellie pulls on a 10-kg wagon with a constant horizontal force of 30 N. If there are no other horizontal forces, what is the wagon's acceleration? A) 0.3 m/s2 B) 3.0 m/s2 C) 10 m/s2 D) 30 m/s2 E) 300 m/s2
Answer: B) 3.0 m/s2
28)An apple falls from a tree and hits the ground 5 meters below with a speed of about A) 4.89m/s. B) 9.89m/s. C) 19.6m/s. D) 49.0m/s.
Answer: B) 9.89m/s.
30)If a freely falling object were equipped with a speedometer, its speed reading would increase each second by about A) 4.9m/s. B) 9.8m/s. C) 19.6m/s. D) a variable amount. E) depends on its initial speed
Answer: B) 9.8m/s.
3) The main difference between a scalar and a vector quantity is: A) Magnitude B) Direction C) Unit
Answer: B) Direction
46)Two point masses m and M are separated by a distance d. If the distance between the masses is increased to 3d, how does the gravitational force between them change? A) The force will be one-third as great. B) The force will be one-ninth as great. C) The force will be three times as great. D) The force will be nine times as great. E) It is impossible to determine without knowing the numerical values of m, M, and d.
Answer: B) The force will be one-ninth as great.
86)In a collision between a small car and a large truck, the car and the truck undergo the same change in their velocities.
Answer: FALSE
88)When a moving object hits a stationary object and causes it to move, some of the moving object's kinetic energy is transformed into momentum in the object that was at rest.
Answer: FALSE
89)If a force acts perpendicular to an object's direction of motion, that force cannot change the object's kinetic energy or momentum.
Answer: FALSE
17) You throw a 5.0 kg stone from the top of a cliff with an initial vertical velocity of 8.0 m/s downward and an initial horizontal velocity of 7.0 m/s away from the cliff, and it feels no air resistance. After the stone is in the air but free of your hand, its acceleration remains constant at 9.8 m/s2 downward but its speed changes.
Answer: TRUE
5) The magnitude of the resultant of two vectors must be greater than or equal to the magnitude of each of these vector.
Answer: FALSE
23) What is the acceleration of projectile when it reaches its maximum height? A) zero m/s2 B) 9.8 m/s2, downward C) 4.9 m/s2, downward D) less than 9.8 m/s2 and non-zero. E) Its magnitude is 9.8 m/s2; and its direction is changing.
Ans: B) 9.8 m/s2, downward
21) A football is kicked at an angle with respect to the horizontal. Which one of the following statements best describes the acceleration of the football during this event if air resistance is neglected? A) The acceleration is zero m/s2 at all times. B) The acceleration is 9.8 m/s2 at all times. C) The acceleration is zero m/s2 when the football has reached the highest point in its trajectory. D) The acceleration is positive as the football rises, and it is negative as the football falls. E) The acceleration starts at 9.8 m/s2 and drops to some constant lower value as the ball approaches the ground.
Ans: B) The acceleration is 9.8 m/s2 at all times.
22) A baseball is hit upward and travels along a parabolic arc before it strikes the ground. Which one of the following statements is necessarily true? A) The acceleration of the ball decreases as the ball moves upward. B) The velocity of the ball is zero m/s when the ball is at the highest point in the arc. C) The acceleration of the ball is zero m/s2 when the ball is at the highest point in the arc. D) The x-component of the velocity of the ball is the same throughout the ball's flight. E) The velocity of the ball is a maximum when the ball is at the highest point in the arc.
Ans: D) The x-component of the velocity of the ball is the same throughout the ball's flight.
24) A projectile fired from a gun has initial horizontal and vertical components of velocity equal to 30 m/s and 40 m/s, respectively. What is the magnitude of the projectile's velocity just before it strikes the ground? A) zero m/s B) 9.8 m/s C) 30 m/s D) 40 m/s E) 50 m/s
Ans: E) 50 m/s
26) A tennis ball is thrown upward at an angle from point A. It follows a parabolic trajectory and hits the ground at point D. At the instant shown, the ball is at point B. Point C represents the highest position of the ball above the ground. At which point is the velocity vector changing most rapidly with time? A) A B) B C) C D) D E) It is changing at the same rate at all four points.
Ans: E) It is changing at the same rate at all four points.
25) A tennis ball is thrown upward at an angle from point A. It follows a parabolic trajectory and hits the ground at point D. At the instant shown, the ball is at point B. Point C represents the highest position of the ball above the ground. While in flight, how do the x and y components of the velocity vector of the ball compare at the points A and D? A) The velocity components are non-zero at A and are zero m/s at D. B) The velocity components are the same in magnitude and direction at both points. C) The velocity components have the same magnitudes at both points, but their directions are reversed. D) The velocity components have the same magnitudes at both points, but the directions of the x components are reversed. E) The velocity components have the same magnitudes at both points, but the directions of the y components are reversed.
Ans: E) The velocity components have the same magnitudes at both points, but the directions of the y components are reversed.
16) You walk from your house to the store 1.0 km in 25 minutes, and then you spent 10 minutes in the store. In your way back home, you stop after 15 minutes walking in your friend house, which is located at 0.76 km from the store. Your average velocity was: A) 0.08 m/s B) 0.25 m/s C) 0.32 m/s D) 0.58 m/s
Answer: A) 0.08 m/s
1) A mosquito flying at 3 m/s that encounters a breeze blowing at 3 m/s in the opposite direction A) 0 m/s. B) 3 m/s. C) 4 m/s. D) 6 m/s.
Answer: A) 0m/s
91)The speed of a 4-kg ball with a momentum of 12 kg m/s is A) 3 m/s. B) 4 m/s. C) 12 m/s. D) 48 m/s.
Answer: A) 3 m/s
32)A projectile is fired into the air at an angle of 50° above ground level and hits a target downrange. It will also hit the target if fired at an angle of A) 40°. B) 45°. C) 55°. D) 60°. E) none of the above
Answer: A) 40°
34)A projectile is fired into the air at an angle of 50° above ground level and hits a target downrange. It will also hit the target if fired at an angle of A) 40°. B) 45°. C) 55°. D) 60°. E) none of the above
Answer: A) 40°
85)A 480 kg car moving at 14.4 m/s hits from behind another car moving at 13.3 m/s in the same direction. If the second car has a mass of 570 kg and a new speed of 17.9 m/s, what is the velocity of thefirst car after the collision? A) 8.94 m/s B) 10.5 m/s C) 19.9 m/s D) -8.94 m/s
Answer: A) 8.94 m/s
37)Complete the following statement: An inertial reference frame is one in which A) Newton's first law of motion is valid. B) the inertias of objects within the frame are zero. C) the frame is accelerating. D) the acceleration due to gravity is greater than zero m/s2. E) Newton's second law of motion is not valid.
Answer: A) Newton's first law of motion is valid.
76)Complete the following statement: In an isolated system, the total mechanical energy remains constant if A) all exerted forces are conservative. B) all exerted forces are nonconservative. C) the work done by nonconservative forces is positive. D) the work done by nonconservative forces is negative. E) an object returns to its starting position.
Answer: A) all exerted forces are conservative.
98)A softer landing occurs when an falling object bounces from a surface A) in a extended time. B) quickly. C) either of these D) neither of these
Answer: A) in a extended time.
41)If your automobile runs out of fuel while driving, the engine stops. You don't come to an abrupt stop due to A) inertia. B) gravity. C) resistance. D) the principle of continuation.
Answer: A) inertia
78)Complete the following statement: In situations involving non-conservative external forces, the work done by these forces A) is always negative. B) is always equal to zero. C) is always positive. D) can be either positive or negative. E) usually cannot be determined.
Answer: A) is always negative.
92)A large heavy truck and a small baby carriage roll down a hill. Neglecting friction, at the bottom of the hill, the baby carriage will likely have A) less momentum. B) about the same momentum. C) more momentum.
Answer: A) less momentum
61)A lunar month is about 28 days. If the Moon were closer to Earth than it is now, the lunar month would be A) less than 28 days. B) about 28 days. C) more than 28 days. D) need more information
Answer: A) less than 28 days.
68)Complete the following statement: If positive work is done on a moving object, A) the velocity of the object will increase. B) the velocity of the object will decrease. C) the kinetic energy of the object will decrease. D) the velocity of the object will not change. E) the direction of the acceleration of the object will be opposite to its displacement.
Answer: A) the velocity of the object will increase.
42)Two students engaged in a tug-of-war each pull a rope in opposite directions with a force of 400 N. The net force on the rope is A) zero and rope tension is 400 N. B) zero and rope tension is 800 N. C) 400 N and rope tension is 800 N. D) 400 N and rope tension is also 400 N.
Answer: A) zero and rope tension is 400 N.
35)What is the main difference between the mass and the weight of an object? A)Mass is the amount of matter in an object, weight is the gravitational force that acts on an object. B)Weight is the amount of matter in an object, mass is the gravitational force that acts on an object C)You weight is the same no matter where you are, the mass depend of the gravitational force D)Weight and mass are the same
Answer: A)Mass is the amount of matter in an object, weight is the gravitational force that acts on an object.
67)Force acts on a particle and does work . Force acts simultaneously on the particle and does work . The speed of the particle does not change. Which one of the following must be true? A) W1 is zero and W2 is positive B) W1 = -W2 C) W1 is positive and W2 is zero D) W1 is positive and W2 is positive
Answer: B
8) A pair of 10-N vectors at right angles to each other has a resultant of about A) 10 N. B) 14 N. C) 20 N.
Answer: B) 14 N.
51)Two-point masses m and M are separated by a distance d. If the distance between the masses is increased to 3d, how does the gravitational force between them change? A) The force will be one-third as great. B) The force will be one-ninth as great. C) The force will be three times as great. D) The force will be nine times as great. E) It is impossible to determine without knowing the numerical values of m, M, and d.
Answer: B) The force will be one-ninth as great.
94)It is correct to say that impulse is equal to A) momentum. B) a corresponding change in momentum. C) force multiplied by the distance it acts. D) velocity multiplied by time.
Answer: B) a corresponding change in momentum.
74)In which one of the following systems is there a decrease in gravitational potential energy? A) a boy stretches a horizontal spring B) a girl jumps down from a bed C) a crate rests at the bottom of an inclined plane D) a car ascends a steep hill E) water is forced upward through a pipe
Answer: B) a girl jumps down from a bed
11) While a car travels around a circular track at a constant speed, its A) acceleration is zero. B) acceleration is constant C) acceleration increases D) acceleration decreases
Answer: B) acceleration is constant
97)A karate chop is more effective if one's hand A) follows through upon impact. B) bounces upon impact. C) extends the time upon impact.
Answer: B) bounces upon impact.
13) If an object moves with constant acceleration, its velocity must A) be constant also. B) change by the same amount each second. C) change by varying amounts depending on its speed. D) always decrease.
Answer: B) change by the same amount each second.
71)Two identical golf carts move at different speeds. The faster cart has twice the speed and therefore has A) twice the kinetic energy. B) four times the kinetic energy. C) eight times the kinetic energy.
Answer: B) four times the kinetic energy.
10) The direction of the resultant of a vertical 40-N force at right angles to a horizontal 30-N force is A) 45 degrees B) greater than 45 degrees C) Less than 45 degrees
Answer: B) greater than 45 degrees
48)According to the Newton's second Law, if you double the force acting on an object of mass m, then it acceleration will A) not change at all. B) increase by a factor of 2. C) decrease by a factor of 2. D) increase by a factor of 4. E) decrease by a factor of 4.
Answer: B) increase by a factor of 2.
36)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) inertia C) acceleration D) equilibrium E) force
Answer: B) inertia
45)According to the universal law of gravitation, the force due to gravity is A) directly proportional to the square of the distance between objects. B) inversely proportional to the square of the distance between objects. C) directly proportional to the distance between objects. D) inversely proportional to the distance between objects. E) not dependent on the distance between objects.
Answer: B) inversely proportional to the square of the distance between objects.
62)Minimal orbit speed about Earth is about 8 km/s, and about Jupiter is A) less than 8 km/s. B) more than 8 km/s. C) about 8 km/s.
Answer: B) more than 8 km/s
58)An astronaut at Earth's surface has a mass of 50 kg and a weight of 490N. If she were floating freely inside a space habitat in remote space, she would have A) no weight and less mass. B) no weight and the same mass. C) more weight and no mass. D) none of the above
Answer: B) no weight and the same mass.
79)The power due to a force depends on which of the following parameters? A)the magnitude of the force and the displacement of the object B)the magnitude of the force and the velocity of the object C)the mass of the object and the velocity of the object D)the work done on the object and its displacement E)the mass of the object and the displacement of the object
Answer: B)the magnitude of the force and the velocity of the object
15) You walk from your house to the store 1.0 km in 25 minutes, and then you spent 10 minutes in the store. In your way back home, you stop after 15 minutes walking in your friend house, which is located at 0.76 km from the store. Your average speed was: A) 0.73 m/s B) 0.68 m/s C) 0.59 m/s D) 0.33 m/s
Answer: C) 0.59 m/s
99)A 1-kg glider and a 2-kg glider both slide toward each other at 1 m/s on an air track. They collide and stick. The combined mass moves at A) 0 m/s. B) 1/2 m/s. C) 1/3 m/s. D) 1/6 m/s. E) 1.5 m/s.
Answer: C) 1/3 m/s
50)When a baseball player bats a ball with a force of 1000 N, the reaction force that the ball exerts against the bat is A) less than 1000 N. B) more than 1000 N. C) 1000 N. D) need more information
Answer: C) 1000N
65)Escape speed from Earth is A) 8 km/s. B) 9 km/s. C) 11.2 km/s. D) 63 km/s.
Answer: C) 11.2 km/s
29)If a stone falls to the bottom of a mineshaft in 6 seconds, then the depth of the shaft is about A) 58.8m. B) 29.4m. C) 176.4m. D) more than 200 m.
Answer: C) 176.4m.
14) You walk from your house to the store 1.0 km in 25 minutes, and then you spent 10 minutes in the store. In your way back home, you stop after 15 minutes walking in your friend house, which is located at 0.76 km from the store. Your displacement was: A) 760 m B) 1000 m C) 240 m D) 1760 m
Answer: C) 240 m
93)A motorcycle of mass 100 kilograms slowly rolls off the edge of a cliff and falls for three seconds before reaching the bottom of a gully. Its momentum upon hitting the ground is A) 1,000 kg m/s. B) 2,000 kg m/s. C) 3,000 kg m/s. D) 4,000 kg m/s. E) 9,000 kg m/.
Answer: C) 3,000 kg m/s
9) The resultant of a 40-N force at right angles to a 30-N force is A) 30 N. B) 40 N. C) 50 N. D) 60 N.
Answer: C) 50 N.
100)A 5000-kg freight car collides with a 10,000-kg freight car at rest. They couple upon collision and move at 2 m/s. What was the initial speed of the 5000-kg car? A) 4 m/s B) 5 m/s C) 6 m/s D) 8 m/s
Answer: C) 6 m/s
55)Satellites in orbit are accelerated toward Earth, so they must be getting closer and closer to our planet.
Answer: FALSE
20) Ball 1 is thrown into the air and it follows the trajectory for projectile motion shown in the drawing. At the instant that ball 1 is at the top of its trajectory, ball 2 is dropped from rest from the same height. Which ball reaches the ground first? A) Ball 1 reaches the ground first, since it is moving at the top of the trajectory, while ball 2 is dropped from rest. B) Ball 2 reaches the ground first, because it has the shorter distance to travel. C) Both balls reach the ground at the same time. D) There is not enough information to tell which ball reaches the ground first.
Answer: C) Both balls reach the ground at the same time.
6) The direction of the resultant of a vertical 50-N force at right angles to a horizontal 80-N force is A) 45 degrees B) greater than 45 degrees. C) Less than 45 degrees
Answer: C) Less than 45 degrees
75)Which one of the following statements concerning the principle of the conservation of mechanical energy is true? A) Mechanical energy is always conserved in situations where the kinetic energy is constant. B) Mechanical energy is always conserved in situations where the gravitational potential energy is constant. C) Mechanical energy is always conserved in situations where external non-conservative forces do no work. D) Mechanical energy is always conserved in situations where external conservative forces do no work. E) Mechanical energy is always conserved in situations where the gravitational potential energy is zero joules.
Answer: C) Mechanical energy is always conserved in situations where external non-conservative forces do no work.
57)The Moon does not crash into Earth because A) Earth's gravitational field is relatively weak at the Moon. B) gravitational pull of other planets keeps the Moon up. C) Moon has a sufficient tangential speed. D) Moon has less mass than Earth. E) none of the above
Answer: C) Moon has a sufficient tangential speed.
73)Which task requires more work? A) lifting the 50-kg sack 2 meters B) lifting the 25-kg sack 4 meters C) both require the same D) need more information
Answer: C) both require the same
90)Which has the greater momentum when moving? A) a container ship B) a bullet C) either of these depending on speed
Answer: C) either of these depending on speed
40)Whirl a rock at the end of a string and it follows a circular path. If the string breaks, the tendency of the rock is to A) follow a circular path. B) slow down. C) follow a straight-line path. D) stop.
Answer: C) follow a straight-line path.
59)A weightless astronaut in an orbiting satellite is A) shielded from Earth's gravitational field. B) beyond the pull of gravity. C) like the satellite, pulled by Earth's gravitation. D) none of the above
Answer: C) like the satellite, pulled by Earth's gravitation.
64)A weightless astronaut in an orbiting satellite is A) shielded from Earth's gravitational field. B) beyond the pull of gravity. C) like the satellite, pulled by Earth's gravitation. D) none of the above
Answer: C) like the satellite, pulled by Earth's gravitation.
60)A lunar month is about 28 days. If the Moon were farther from Earth than it is now, the lunar month would be A) less than 28 days. B) about 28 days. C) more than 28 days. D) need more information
Answer: C) more than 28 days.
44)A force of 1 N accelerates 1-kg box at the rate of 1 m/s2. The acceleration of a 2-kg box by a net force of 2 N is A) half as much. B) twice as much. C) the same. D) none of the above
Answer: C) the same
70)Both a 50-kg sack is lifted 2 meters from the ground and a 25-kg sack is lifted 4 meters in the same time. The power expended in raising the 50-kg sack is A) twice as much as the 25-kg sack. B) half as much as the 25-kg sack. C) the same. D) need more information
Answer: C) the same.
47)The force of gravity is an inverse square law. This means that, if you double the distance between two large masses, the gravitational force between them A) also doubles. B) strengthens by a factor of 4. C) weakens by a factor of 4. D) weakens by a factor of 2. E) is unaffected.
Answer: C) weakens by a factor of 4.
53)The force of gravity is an inverse square law. This means that, if you double the distance between two large masses, the gravitational force between them A) also doubles. B) strengthens by a factor of 4. C) weakens by a factor of 4. D) weakens by a factor of 2. E) is unaffected.
Answer: C) weakens by a factor of 4.
56)A satellite orbits the Earth in uniform circular motion. What is the direction of centripetal acceleration of the satellite? A)Because the centripetal acceleration is a scalar quantity, it doesn't have a direction. B)The centripetal acceleration vector points radially outward from the Earth. C)The centripetal acceleration vector points radially inward toward the Earth. D)The centripetal acceleration vector points in the direction of the satellite's velocity. E)The centripetal acceleration vector points in the direction opposite that of the satellite's velocity.
Answer: C)The centripetal acceleration vector points radially inward toward the Earth.
2) When you walk at an average speed of 4 m/s, in 5 s you'll cover a distance of A) 2 m. B) 10 m. C) 15 m. D) 20 m.
Answer: D) 20 m.
80)You are investigating the safety of a playground slide. You are interested in finding out what the maximum speed will be of children sliding on it when the conditions make it very slippery (assume frictionless). The height of the slide is 2.5 m. What is that maximum speed of a child if she starts from rest at the top? A)1.9 m/s B)2.5 m/s C)4.9 m/s D)7.0 m/s E)9.8 m/s
Answer: D) 7.0 m/s
31)A projectile is launched from ground level at 15° above the horizontal and lands downrange. What other projection angle for the same speed would produce the same down-range distance? A) 30° B) 45° C) 50° D) 75° E) 90°
Answer: D) 75°
33)A projectile is launched from ground level at 15° above the horizontal and lands downrange. What other projection angle for the same speed would produce the same down-range distance? A) 30° B) 45° C) 50° D) 75° E) 90°
Answer: D) 75°
18) You can launch a projectile with a fixed initial speed but at any angle above the horizontal, and it feels no air resistance. The time for it to return to the ground does not depend on the angle at which you launch it.
Answer: FALSE
4) Which one of the following statements concerning vectors and scalars is false? A) In calculations, the vector components of a vector may be used in place of the vector itself. B) It is possible to use vector components that are not perpendicular. C) A scalar component may be either positive or negative. D) A vector that is zero may have components other than zero. E) Two vectors are equal only if they have the same magnitude and direction.
Answer: D) A vector that is zero may have components other than zero.
7) When a pair of 10-N forces act on a box of candy, the net force on the box is A) zero. B) about 14 N. C) 20 N. D) Any of the above depending on the directions of forces.
Answer: D) Any of the above depending on the directions of forces.
82)Which one of the following is characteristic of an inelastic collision? A) Total mass is not conserved. B) Total energy is not conserved. C) Linear momentum is not conserved. D) Kinetic energy is not conserved. E) The change in momentum is less than the total impulse.
Answer: D) Kinetic energy is not conserved.
52)Two-point masses m and M are separated by a distance d. If the distance between the masses is decreases by 1/2 d, how does the gravitational force between them change? A) The force will be one-half as great. B) The force will be one-four as great. C) The force will be two times as great. D) The force will be four times as great. E) It is impossible to determine without knowing the numerical values of m, M, and d.
Answer: D) The force will be four times as great.
49)Two point masses m and M are separated by a distance d. If the separation d remains fixed and the masses are increased to the values 3m and 3M respectively, how does the gravitational force between them change? A) The force will be one-third as great. B) The force will be one-ninth as great. C) The force will be three times as great. D) The force will be nine times as great. E) It is impossible to determine without knowing the numerical values of m, M, and d.
Answer: D) The force will be nine times as great.
54)Two-point masses m and M are separated by a distance d. If the separation d remains fixed and the masses are increased to the values 3m and 3M respectively, how does the gravitational force between them change? A) The force will be one-third as great. B) The force will be one-ninth as great. C) The force will be three times as great. D) The force will be nine times as great. E) It is impossible to determine without knowing the numerical values of m, M, and d.
Answer: D) The force will be nine times as great.
12) Which of the following statements about velocity is not true? A) Average velocity is the displacement of an object divided by the time interval B) Velocity is a vector quantity C) It measures how fast and in what direction the particle is moving D) Velocity is always a positive
Answer: D) Velocity is always a positive
39)If gravity between the Sun and Earth suddenly vanished, Earth would continue moving in A) a curved path. B) an outward spiral path. C) an inward spiral path. D) a straight-line path.
Answer: D) a straight-line path.
95)A car traveling along the highway brakes to a stop over a certain distance. More braking force is required if the car has A) more mass. B) more momentum. C) less stopping distance. D) all of the above E) none of the above
Answer: D) all of the above
27)Twelve seconds after starting from rest, a freely-falling cantelope has a speed of A) 9.8m/s. B) 49m/s. C) 100 m/s. D) more than 100 m/s.
Answer: D) more than 100 m/s.
63)The period of an Earth satellite depends on the satellite's A)mass. B)volume C)weight on Earth. D)radial distance from Earth.
Answer: D) radial distance from Earth.
72)A bicycle that travels four as fast as another when braking to a stop will skid A) twice as far. B) four times as far. C) eight times as far D) sixteen times as far. E) depends on the mass of the bike
Answer: D) sixteen times as far.
83)Complete the following statement: Momentum will be conserved in a two-body collision only if A) both bodies come to rest. B) the collision is perfectly elastic. C) the kinetic energy of the system is conserved. D) the net external force acting on the two-body system is zero. E) the internal forces of the two body system cancel in action-reaction pairs.
Answer: D) the net external force acting on the two-body system is zero.
69)In which one of the following circumstances does the force do positive work on the object? A)The direction of the force is perpendicular to the object's displacement. B)The direction of the force is in the opposite direction to the object's displacement. C)No matter the direction of the force, positive work will be done if there is a displacement of the object. D)The direction of the force is in the same direction as the object's displacement. E)The object's displacement is zero meters as the force is applied.
Answer: D)The direction of the force is in the same direction as the object's displacement.
66)Two forces and act on a particle. As a result the speed of the particle increases. Which one of the following is NOT possible? A)The work done by is positive, and the work done by is zero. B)The work done by is zero, and the work done by is positive. C)The work done by each force is positive. D)The work done by each force is negative. E)The work done by is positive, and the work done by is negative
Answer: D)The work done by each force is negative.
84)Two objects of equal mass traveling toward each other with equal speeds undergo a head on collision. Which one of the following statements concerning their velocities after the collision is necessarily true? A) They will exchange velocities. B) Their velocities will be reduced. C) Their velocities will be unchanged. D) Their velocities will be zero. E) Their velocities may be zero.
Answer: E) Their velocities may be zero.
81)Complete the following statement: A collision is elastic if A) the final velocities are zero. B) the objects stick together. C) the final kinetic energy is zero. D) the final momentum is zero. E) the total kinetic energy is conserved.
Answer: E) the total kinetic energy is conserved.
77)Complete the following statement: The total mechanical energy of a system remains unchanged if A) the external forces acting on the system are nonconservative. B) the external forces acting on the system are conservative. C) the kinetic energy is constant. D) the potential energy is constant. E) there are no external forces acting on the system.
Answer: E) there are no external forces acting on the system
19) A ball is thrown at an angle above the horizontal from the top of a cliff and feels no air resistance. A runner at the base of the cliff moves horizontally so that she is always under the ball. In this runner's reference frame, the path of the ball is a straight line rather than a parabola.
Answer: TRUE
38)You are in a train traveling on a horizontal track and notice that a piece of luggage starts to slide toward the front of the train. From this observation, you can conclude that this train is not an inertial reference frame because it is slowing down.
Answer: TRUE
87)Kinetic energy is conserved only in perfectly elastic collisions, but momentum is conserved in all collisions.
Answer: TRUE
