Q&A Hero

Q: One radian is approximately A) 10 B) 33 C) 57 D) 90 E) 180

Q: Vectors and lie in the xyplane. We can deduce that if: A) Ax2+ Ay2= Bx2+ By2 B) Ax+ Ay= Bx+ By C) Ax= Bxand Ay= By D) Ay/Ax= By/Bx E) Ax= Ayand Bx= By

Q: Four vectors all have the same magnitude. The angle between adjacent vectors is 45as shown. The correct vector equation is: A) B) C) D) E)

Q: If and neither nor vanish, then: A) and are parallel and in the same direction B) and are parallel and in opposite directions C) the angle between and is 45ï‚° D) the angle between and is 60ï‚° E) is perpendicular to

Q: The vector in the diagram is equal to: A) B) C) D) E)

Q: The vectors ,, and are related by . Which diagram below illustrates this relationship? A) I. B) II. C) III. D) IV. E) None of these

Q: The vector is: A) greater than in magnitude B) less than in magnitude C) in the same direction as D) in the direction opposite to E) perpendicular to

Q: If and neither nor vanish, then: A) and are parallel and in the same direction B) and are parallel and in opposite directions C) the angle between and is 45ï‚° D) the angle between and is 60ï‚° E) is perpendicular to

Q: If , then: A) and must be parallel and in the same direction B) and must be parallel and in opposite directions C) it must be true that either or is zero D) the angle between and must be 60ï‚° E) none of the above is true

Q: A vector of magnitude 6 and another vector have a resultant of magnitude 12. The vector: A) must have a magnitude of at least 6 but no more than 18 B) may have a magnitude of 20 C) cannot have a magnitude greater than 12 D) must be perpendicular to E) must be perpendicular to the resultant vector

Q: A vector of magnitude 20 is added to a vector of magnitude 25. The magnitude of this sum can be: A) 0 B) 3 C) 12 D) 47 E) 50

Q: A vector of magnitude 3 CANNOT be added to a vector of magnitude 4 so that the magnitude of the resultant is: A) 0 B) 1 C) 3 D) 5 E) 7

Q: We say that the displacement of a particle is a vector quantity. Our best justification for this assertion is: A) displacement can be specified by a magnitude and a direction B) operating with displacements according to the rules for manipulating vectors leads to results in agreement with experiments C) a displacement is obviously not a scalar D) displacement can be specified by three numbers E) displacement is associated with motion

Q: This graph shows the velocity of a particle as a function of time. During what interval is its displacement negative? A) 0 " 2 s B) 2s " 5 s C) 5 s " 9 s D) 0 " 9 s E) Its displacement is not negative between 0 and 9 s.

Q: An object is thrown vertically into the air. Which of the following five graphs represents the velocity (v) of the object as a function of the time (t)? The positive direction is taken to be upward. A) I B) II C) III D) IV E) V

Q: A stone is dropped from a cliff. The graph (carefully note the axes) that best represents its motion while it falls is: A) I B) II C) III D) IV E) V

Q: An object is dropped from rest. Which of the five following graphs correctly represents its motion? The positive direction is taken to be upward. Take careful note of the axes. A) I B) II C) III D) IV E) V

Q: One object is thrown vertically upward with an initial velocity of 100 m/s and another object with an initial velocity of 10 m/s. The maximum height reached by the first object will be _______ that of the other. A) 10 times B) 100 times C) 1000 times D) 10,000 times E) none of these

Q: A projectile is shot vertically upward with a given initial velocity. It reaches a maximum height of 100 m. If on a second shot the initial velocity is doubled, then the projectile will reach a maximum height of: A) 70.7 m B) 141.4 m C) 200 m D) 241 m E) 400 m

Q: An object is thrown vertically upward with a certain initial velocity in a world where the acceleration due to gravity is 19.6 m/s2. The height to which it rises is ____ that to which the object would rise if thrown upward with the same initial velocity on the Earth. Neglect air resistance. A) one fourth B) half C) twice D) four times E) cannot be calculated from the given data

Q: A stone is released from rest from the edge of a building roof 190 m above the ground. Neglecting air resistance, the speed of the stone, just before striking the ground, is: A) 43 m/s B) 61 m/s C) 120 m/s D) 190 m/s E) 1400 m/s

Q: An object is thrown straight down with an initial speed of 4 m/s from a window which is 8 m above the ground. The time it takes the object to reach the ground is: A) 0.80 s B) 0.93 s C) 1.3 s D) 1.7 s E) 2.0 s

Q: A baseball is hit straight up and is caught by the catcher 2.0 s later, at the same height at which it left the bat. The maximum height of the ball during this interval is: A) 4.9 m B) 7.4 m C) 12.4 m D) 19.6 m E) 38.8 m

Q: A stone is thrown vertically upward with an initial speed of 19.5 m/s. It will rise to a maximum height of: A) 4.9 m B) 9.8 m C) 19.4 m D) 38.8 m E) none of these

Q: Neglecting the effect of air resistance, a stone dropped off a 175-m high building lands on the ground in: A) 3 s B) 4 s C) 6 s D) 18 s E) 36 s

Q: An object dropped from a window of a tall building hits the ground in 12.0 s. If its acceleration is 9.80 m/s2, the height of the window above the ground is (you may neglect air resistance): A) 29.4 m B) 58.8 m C) 118 m D) 353 m E) 706 m

Q: A stone is released from a balloon that is descending at a constant speed of 10 m/s. Neglecting air resistance, after 20 s the speed of the stone is: A) 2160 m/s B) 1760 m/s C) 206 m/s D) 196 m/s E) 186 m/s

Q: A heavy ball falls freely, starting from rest. Between the third and fourth second of its fall it travels a distance of: A) 4.9 m. B) 9.8 m. C) 29.4 m D) 34.3 m. E) 39.8 m.

Q: An object is released from rest.How far does it fall during the second second of its fall? A) 4.9 m B) 9.8 m C) 15 m D) 20 m E) 25 m

Q: An object is thrown vertically upward at 35 m/s. Taking g = 10 m/s2, the velocity of the object 5 seconds later is: A) 7.0 m/s up B) 15 m/s down C) 15 m/s up D) 85 m/s down E) 85 m/s up

Q: At a location where g = 9.80 m/s2, an object is thrown vertically down with an initial speed of 1.00 m/s. After 5.00 s the object will have traveled: A) 125 m B) 128 m C) 245 m D) 250 m E) 255 m

Q: An object is thrown straight up from ground level with a speed of 50 m/s. If g = 10 m/s2 its distance above ground level 6.0 s later is: A) 0.00 m B) 270 m C) 330 m D) 480 m E) none of these

Q: An object is thrown straight up from ground level with a speed of 50 m/s. If g = 10 m/s2 its distance above ground level 1.0 second later is: A) 40 m B) 45 m C) 50 m D) 55 m E) 60 m

Q: A freely falling body has a constant acceleration of 9.8 m/s2. This means that: A) the body falls 9.8 m during each second B) the body falls 9.8 m during the first second C) the speed of the body increases by 9.8 m/s during each second D) the acceleration of the body increases by 9.8 m/s2 during each second E) the acceleration of the body decreases by 9.8 m/s2 during each second

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

Q: As a rocket is accelerating vertically upward at 9.8 m/s2 near the Earth's surface, it releases a projectile. Immediately after release the acceleration of the projectile is: A) 9.8 m/s2 down B) 0 m/s2 C) 9.8 m/s2 up D) 19.6 m/s2 up E) none of the above

Q: If you drop a rock and a feather, the rock hits the ground first. This demonstrates that: A) The acceleration of gravity is not constant. B) Heavier objects are accelerated faster by gravity than lighter objects are. C) Air resistance has a larger effect on feathers than on rocks. D) Rocks can"t fly. E) Gravity has little effect on a feather.

Q: 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? A) A B) B C) C D) D E) E

Q: A ball is thrown upwards. Its acceleration is: A) downward during both ascent and descent B) downward during ascent and upward during descent C) upward during ascent and downward during descent D) upward during both ascent and descent E) downward at all times except at the very top, when it is zero

Q: A feather, initially at rest, is released in a vacuum 12 m above the surface of the Earth. Which of the following statements is correct? A) The maximum velocity of the feather is 9.8 m/s B) The acceleration of the feather decreases until terminal velocity is reached C) The acceleration of the feather remains constant during the fall D) The acceleration of the feather increases during the fall E) The acceleration of the feather is zero

Q: A baseball is thrown vertically into the air. The acceleration of the ball at its highest point is: A) zero B) g, down C) g, up D) 2g. down E) 2g, up

Q: An object is shot vertically upward. While it is rising: A) its velocity and acceleration are both upward B) its velocity is upward and its acceleration is downward C) its velocity and acceleration are both downward D) its velocity is downward and its acceleration is upward E) its velocity and acceleration are both decreasing

Q: Which of the following is NOT true of an object in free fall in the absence of air resistance? A) Its acceleration is constant. B) If its initial velocity is upwards, it will reach a maximum height and then begin to fall. C) If its initial velocity is zero, its position below its starting point can be calculated knowing only how long ago it began falling. D) Its velocity will always be zero at some point along its path. E) Its velocity changes by the same amount every second.

Q: A ball is in free fall motion. Upward is taken to be the positive direction. The displacement of the ball is: A) positive during both ascent and descent B) negative during both ascent and descent C) negative during ascent and positive during descent D) positive during ascent and negative during descent E) none of the above

Q: A drag racing car starts from rest at t = 0 and moves along a straight line with velocity given by v = bt2, where b is a constant. The expression for the distance traveled by this car from its position at t = 0 is: A) bt3 B) bt3/3 C) 4bt2 D) 3bt2 E) bt3/2

Q: Displacement can be obtained from: A) the slope of an acceleration-time graph B) the slope of a velocity-time graph C) the area under an acceleration-time graph D) the area under a velocity-time graph E) the slope of an acceleration-time graph

Q: The velocity of an object is given as a function of time by v = 4t - 3t2, where v is in m/s and t is in seconds. Its average velocity over the interval from t = 0 s to t = 2 s:A) is 0B) is -2 m/sC) is 2 m/sD) is -4 m/sE) cannot be calculated unless the initial position is given

Q: The area under a velocity-time graph represents: A) acceleration B) change in acceleration C) speed D) change in velocity E) displacement

Q: At time t = 0 a car has a velocity of 16 m/s. It slows down with an acceleration given by a = "0.50t, in m/s2 for t in seconds. At the end of 4.0 s it has traveled: A) 0 B) 12 m C) 14 m D) 25 m E) 59 m

Q: At time t = 0 a car has a velocity of 16 m/s. It slows down with an acceleration given by a = "0.50t, in m/s2 for t in seconds. It stops at t = A) 64 s B) 32 s C) 16 s D) 8.0 s E) 4.0 s

Q: At time t = 0 a car has a velocity of 16 m/s. It slows down with an acceleration given bya = "0.50t, in m/s2 for t in seconds. By the time it stops it has traveled: A) 15 m B) 31 m C) 62 m D) 85 m E) 100 m

Q: The acceleration of an object, starting from rest, is shown in the graph below. Other than at t = 0, when is the velocity of the object equal to zero? A) During the interval from 1.0 s to 3.0 s B) At t = 3.5 s C) At t = 4.0 s D) At t = 5.0 s E) At no other time less than or equal to 5 s.

Q: The graph represents the straight line motion of a car. How far does the car travel between t = 2 seconds and t = 5 seconds? A) 4 m B) 12 m C) 24 m D) 36 m E) 60 m

Q: An object starts from rest at the origin and moves along the x axis with a constant acceleration of 4 m/s2. Its average velocity as it goes from x = 2 m to x = 8 m is: A) 1 m/s B) 2 m/s C) 3 m/s D) 5 m/s E) 6 m/s

Q: An object starts from rest and has a constant acceleration of 3 m/s2. The position versus time graph for this object has a slope: A) that increases with time B) that is constant C) that decreases with time D) of 3 m/s E) of 3 m/s2

Q: At a stop light, a truck traveling at 15 m/s passes a car as it starts from rest. The truck travels at constant velocity and the car accelerates at 3 m/s2. How much time does the car take to catch up to the truck? A) 5 s B) 10 s C) 15 s D) 20 s E) 25 s

Q: How far does a car travel in 6 s if its initial velocity is 2 m/s and its acceleration is 2 m/s2 in the same direction as its initial velocity? A) 12 m B) 14 m C) 24 m D) 36 m E) 48 m

Q: An object with an initial velocity of 12 m/s west experiences a constant acceleration of 4 m/s2 west for 3 seconds. During this time the object travels a distance of: A) 18 m B) 24 m C) 36 m D) 54 m E) 144 m

Q: A car moving with an initial velocity of 25 m/s north has a constant acceleration of 3 m/s2 south. After 6 seconds its velocity will be: A) 7 m/s north B) 7 m/s south C) 43 m/s north D) 20 m/s north E) 20 m/s south

Q: A car starts from rest and goes down a slope with a constant acceleration of 5 m/s2. After 5 seconds the car reaches the bottom of the hill. What is its speed at the bottom of the hill? A) 1 m/s B) 12.5 m/s C) 25 m/s D) 50 m/s E) 160 m/s

Q: A racing car traveling with constant acceleration increases its speed from 10 m/s to 30 m/s over a distance of 60 m? How long does this take? A) 2.0 s B) 3.0 s C) 5.0 s D) 6.0 s E) The time cannot be calculated since the speed is not constant

Q: A car, initially at rest, travels 20 m in 4 s along a straight line with constant acceleration. The acceleration of the car is: A) 1.3 m/s2 B) 2.5 m/s2 C) 4.9 m/s2 D) 9.8 m/s2 E) There is not enough information to answer this question.

Q: Consider the following five graphs (note the axes carefully). Which of these represent(s) motion at constant speed? A) IV only B) IV and V only C) I, II, and III only D) I and II only E) I and IV only

Q: The diagram represents the straight line motion of a car. Which of the following statements is true?A) The car'sspeed increases, then it stops, and reversesB) The car accelerates at 6 m/s2 for the first 2 sC) The car is moving for a total time of 12 sD) The car accelerates at -12 m/s2 for the last 4 sE) The car returns to its starting point when t = 9 s

Q: The diagram shows a velocity-time graph for a car moving in a straight line. At point P the car must be: A) moving with zero acceleration B) climbing the hill C) accelerating D) stationary E) moving at about 45 with respect to the x axis

Q: The diagram shows a velocity-time graph for a car moving in a straight line. At point Q the car must be: A) moving with zero acceleration B) traveling downhill C) traveling below ground-level D) reducing speed E) traveling in the reverse direction to that at point P

Q: A car accelerates from rest on a straight road. A short time later, the car decelerates to a stop and then returns to its original position in a similar manner, by speeding up and then slowing to a stop. Which of the following five coordinate versus time graphs best describes the motion? A) I B) II C) III D) IV E) V

Q: A particle moves along the x axis according to the equation x = 6t2 where x is in meters and t is in seconds. Therefore: A) the acceleration of the particle is 6 m/s2 B) t cannot be negative C) the particle follows a parabolic path D) each second the velocity of the particle changes by 9.8 m/s E) none of the above

Q: Starting at time t = 0, an object moves along a straight line. Its coordinate in meters is given by x(t) = 75t - 1.0t3, where t is in seconds. When it momentarily stops its acceleration is:A) 0 m/s2B) -73 m/s2C) -30 m/s2D) -9.8 m/s2E) 9.2 x 103 m/s2

Q: Starting at time t = 0, an object moves along a straight line with velocity in m/s given byv(t) = 98 - 2t2, where t is in seconds. When it momentarily stops its acceleration is:A) 0 m/s2B) -4.0 m/s2C) -9.8 m/s2D) -28 m/s2E) 49 m/s2

Q: Over a short interval, starting at time t = 0, the coordinate of an automobile in meters is given by x(t) = 27t - 4.0t3, where t is in seconds. The magnitudes of the initial (at t = 0) velocity and acceleration of the auto respectively are:A) 0 m/s; 12 m/s2B) 0 m/s; 24 m/s2C) 27 m/s; 0 m/s2D) 27 m/s; 12 m/s2E) 27 m/s; 24 m/s2

Q: Is it possible for an object to have zero velocity and constant nonzero acceleration? A) Yes, but only if it is not moving at all. B) No, if its velocity is zero its acceleration must also be zero. C) Yes, all objects with zero velocity have nonzero acceleration. D) No, if its acceleration is not zero its velocity cannot be zero. E) Yes, but its velocity must only be zero for an instant.

Q: All falling objects experience some air resistance, the effect of which is to decrease acceleration. When the falling object's acceleration reaches zero, the acceleration stops changing. Therefore, if you drop an object and it falls far enough for this to happen, A) its speed continues to increase all the way down. B) its speed reaches a maximum value and then decreases. C) its speed reaches a maximum value and then doesn"t change. D) its speed reaches a maximum value, decreases, and then increases again. E) Any of these things could happen.

Q: Which of the following five acceleration versus time graphs is correct for an object moving in a straight line at a constant velocity of 20 m/s? A) I B) II C) III D) IV E) V

Q: Can an object have positive acceleration and decreasing speed? A) No, this is not possible. B) Yes, speed will always decrease if acceleration is positive. C) Yes, this is possible if the initial velocity is zero. D) Yes, this is possible if the initial velocity is negative. E) Yes, this is possible but only if the object is moving in two dimensions.

Q: Of the following situations, which one is impossible? A) A body having velocity east and acceleration east B) A body having velocity east and acceleration west C) A body having zero velocity and non-zero acceleration D) A body having constant acceleration and variable velocity E) A body having constant velocity and variable acceleration

Q: A particle moves on the x axis. When its acceleration is positive and increasing: A) its velocity must be positive B) its velocity must be negative C) it must be slowing down D) it must be speeding up E) none of the above must be true

Q: Throughout a time interval, while the speed of a particle increases as it moves along the x axis, its velocity and acceleration could 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

Q: Each of four particles moves along an x axis. Their coordinates (in meters) as functions of time (in seconds) are given byparticle 1: x(t) = 3.5 - 2.7t3particle 2: x(t) = 3.5 + 2.7t3particle 3: x(t) = 3.5 + 2.7t2particle 4: x(t) = 3.5 - 3.4t - 2.7t2Which of these particles have constant acceleration?A) All fourB) Only 1 and 2C) Only 2 and 3D) Only 3 and 4E) None of them

Q: The coordinate of an object is given as a function of time by x = 4t2 - 3t3, where x is in meters and t is in seconds. Its average acceleration over the interval from t = 0 to t = 2 s is:A) -8 m/s2B) 4 m/s2C) -10 m/s2D) 10 m/s2E) -13 m/s2