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STRAIGHTER LINE: GENERAL PHYSICS EXAM 1
Which of the following statements related to conversion factors is false? A. A conversion factor is the ratio of the given unit to the required unit. B. A conversion factor does not necessarily convert to standard SI units. C. The expression 60 min / hour is an example of a conversion factor. D. The value of a conversion factor is essentially 1. - Answers-A What are SI units? A. Standard Index units of measurement B. Units from the old English measurement system C. International time units D. Systeme International units of measurement - Answers-D An SI unit is a Systeme Internacionale unit. In most cases, an SI unit is an mks unit or is derived from mks units. Suppose you are told that 15 quarts (qt) = 14.2 liters (L). What is the conversion factor you would use to convert from quarts to liters? What is the conversion factor you would you use to convert liters to quarts? A. quarts to liters: 14.2 L / 15 qtliters to quarts: 15 qt / 14.2 L B. quarts to liters:15 qt + 14.2 Lliters to quarts: 29.2 qt / L C. quarts to liters: 15 qt / 14.2 Lliters to quarts: 1.06 qt / L D. quarts to liters: 15 qt • 14.2 Lliters to quarts: 213 qt / L - Answers-A An object travels a distance d with acceleration (a) over a period of time (t) according to the equation: d=(1/2) at^2. After 2.3 seconds with an acceleration of 9.8 m/s, how far does an object travel? a. d=(1/2)at^2=(1/2)(9.8m/s^2)(2.3s)^2= 26m b. d=(1/2)at^2=(1/2)(9.8m/s^2)(2.3s)^2= 11m c. (1/2)at^2=(1/2)(9.8m/s^2)(2.3s)^2 = 26m/s d. None of the above. - Answers-A Which of the following uses a derived SI unit measurement? a. time b. speed c. distance d. mass - Answers-b The circumference of a circle is defined by the equation C=2πr, where π=3.14. Suppose that r = 0.0347 m. Which of the following correctly shows the circumference of the circle? a. C = 0.378 m b. C = 0.237916 m
c. C = 0.2 m d. C = 0.218 m - Answers-d Which of the following statements about SI distance units is not correct? a. Both a meter and a kilometer are SI units. b. A mile is not an SI unit. c. A meter currently has a universal unit definition. d. Converting a meter to feet is an example of a conversion involving two different SI units for distance. - Answers-d Which of the following does not explain the use of SI units in physics? a. SI units have been universally accepted as the standard by the scientific community. b. SI units are more difficult to manipulate than old English system units (such as the foot and the pound). c. Physicists are able to measure complicated quantities using mks units. d. SI units are arbitrarily defined. - Answers-B Vectors A→ ,B→ and C--> are shown in the figure. Which of the following is correct? a. C→=A→−B→ b. C→=B→−A→ c. C→=A→+B→ d. C→=∣A→∣+∣B→∣ - Answers-a If C→=A→+B→ then the magnitude of C→ or ∣C→∣, is the sum of the magnitudes of A→ and B→ or A→+B→, a. When A and B are in the same direction. b. When A and B are in the opposite direction. c. under no circumstances. d. Answers A and B. - Answers-a In order to understand vectors, you must understand some basic trigonometry. Which of the following correctly relates x,y,t and θ? - Answers-c. x=t cos 0; y=t sin 0 tan0= y/x;t= sq (x^2+y^2) If C→=A→+B→, then the magnitude of C→, or ∣C→∣, is the sum of the magnitudes of A→ and B→, or ∣A→∣+∣B→∣ - Answers-False Suppose you have $100 that you need to convert to Danish kroner. The conversion rate that day is 5.732 Danish kroner for one American dollar. The business that converts your money charges you a flat fee of 50 Danish kroner for the transaction. Use your knowledge of significant figures to decide which of the following shows the correct amount of Danish kroner that you should receive. A. 573.2 Danish kroner B. 500 Danish kroner C. 523.2 Danish kroner
most negative work on the train? - Answers-a. You would apply a force that is in the left to right direction. Suppose that vector A→ and vector B→ are defined in the following manner: A→=(2m)i^−(2m)j^ B→=(4m)i^+(2m)j^ What is the dot product of these two vectors? - Answers-c. 4m^ The angle between two vectors is 175.0°. What is the scalar product of these two vectors if their magnitudes are 4.000 cm and 3.000 cm? - Answers-c. - 11. The scalar or dot product of two vectors A→ and B→ is defined by the expression A→⋅B→= ABcosθ Which of the following statements about the scalar product is not correct? - Answers-d. The angle θ is defined as the angle between either vector and the horizontal axis. Which of the following answer choices related to the dot product of the two vectors is not correct? - Answers-c. The values Ax, Bx, Ay, and By are all greater than 0. Which of the following statements about the dot product of the two vectors is not correct? Assume that one grid line is one unit. - Answers-c. The dot product of the two vectors is a positive value. Which of the following statements about vector A→is not correct? - Answers-c. The value of Ay is negative. consider the diagram of a toy train being pushed from behind at an angle θ relative to the horizontal. The equation for the work done on the train in this example is the scalar product A→⋅B→=AB cos θ. Which part of this expression accounts for the projection of vector B→ in the direction of vector A→? - Answers-c. B cos θ Which of the following shows the correct equations for the cross product of two vectors?
- Answers-The correct answer is: A→×B→=(AyBz−AzBy)i^+(AzBx−AxBz)j^+(AxBy−AyBx)k^∣A→×B→∣=ABsinθ Think about the forces that are at work when you use a wrench, and about the cross product of two vectors: ∣A→×B→∣=ABsinθ∣. What does Bsinθ represent in this expression? - Answers-The correct answer is: Bsinθ is the projection of the applied force vector B→ perpendicular to the direction of vector A→ Two vectors in the XY- plane are defined by the equations: A→=4i^+3j^B→=3i^−4j^ Which of the following answer choices related to the cross product of these two vectors or the measure of angle θ between the two vectors is not correct? - Answers-b. AxB=7^k
Consider the vectors A→ and B→ shown in the picture. Think about an example where B→ represents the force applied to a wrench, and A→�→ represents the wrench. Which of the following statements about these vectors is not correct? - Answers-b. To unscrew a bolt, a force in the direction parallel to the wrench must be applied. This force is a scalar with a magnitude B. For each of the following diagrams estimate A→×B→�→×�→. Which will result in the largest vector pointing out of the screen? Note that A→�→ and B→�→ each have the same magnitude in all of the figures. - Answers-c. Find the cross product of the following two vectors: A→=3i^−2j^ B→=2i^−j^ - Answers-c. 1k^ Suppose you are trying to solve for the cross product of two vectors in the XY-plane that are defined as A→=Axi^+Ayj^ and B→=Bxi^+Byj^ Which of the following statements about these vectors is not correct? - Answers- b.A→×(B→+C→) =( A→×B→)×(A→×C→) Two vectors in the XY- plane are defined by the equations: A→=2i^−2j^B→=3i^+j^�→=2�^−2�^�→=3�^+�^ Which of the following answer choices related to the cross product of these two vectors or the measure of angle θ� between the two vectors is not correct? - Answers-d. θ=45∘ Two vectors in the XY-plane are defined by the equations A→=2i^+5j^B→=−2i^+j^ Suppose you are asked to find the dot product of the two vectors, the cross product of the two vectors, and the measure of the angle θ between the two vectors. Which of the following statements related to any of these operations is not correct? - Answers-a. The angle θ� between the two vectors is 42∘. Look at the plot that shows the position of a falling ball as a function of time, t. Which of the following statements about this event is not correct? - Answers-B. The greatest magnitude of the average velocity occurs from t1 to t2. The graph illustrates the motion of an object. Which of the following statements is correct? - Answers-A. The acceleration of the object increases with time. One of the simplest types of motion is unidirectional motion. Which of the following is the worst example of unidirectional motion? - Answers-C. The motion of ventilation heat as it travels from a furnace to various rooms in a home. The graph shows the motion of a theoretical particle in a particle accelerator.
Air resistance can affect the falling motion of an object. Which of the following statements about air resistance is not correct? - Answers-d. All of the statements are correct. A squirrel sitting on a tree branch 17 m off the ground drops its acorn. Assume that the accorn has a constant acceleration of approximately 10 m / s2. How long will it take the acorn to hit the ground? - Answers-b. 1.8 s An object is observed for a 5 second interval. During this time, the object's velocity increases from 2 m / s to a final velocity and the object travels 75 m. The acceleration of the object is constant. Given this information, which of the following statements is not correct? - Answers-b. The final velocity of the object is 26 m / s. Suppose you throw an object straight up at an initial velocity of 17 m / s. How long will it take for the object to reach its maximum height? - Answers-n. 1.7s Which of the following is not one of the equations of kinematics with constant acceleration? - Answers-b. v2f=v2i+2aΔt You can manipulate the expression v¯¯¯=Δx/Δt to find one of the three master equations of kinematics. Which of the following is the master equation that gives an expression for xf? - Answers-D. : xf=xi+viΔt+(1/2)a(Δt) Which of the following does not show or describe constant acceleration? - Answers- graph - c. upwards The drawing shows the initial and final velocity vectors for a moving object, as well as Δv¯¯¯→Δ�¯→. What is the direction of the average acceleration vector, a¯¯¯→�¯→?
- Answers-The correct answer is: Vector a¯¯¯�¯ points in the same direction as Δv¯¯¯→Δ�¯→. Suppose a train starts at point A and 35 seconds later, it reaches point B. What are the initial and final position vectors of the train? - Answers-The correct answer is: ri→=50mi^+100mj^rf→=225mi^−125mj^ The acceleration vector can be assessed in terms of a||�|| and a⊥�⊥. The parallel component is parallel to the direction of the velocity vector. Considering the velocity and acceleration vectors shown on the picture, which of the following statements is not correct? - Answers-The correct answer is: The object is slowing down and shifting in a counterclockwise direction. Which of the following expressions correctly relates v¯¯¯→�¯→, ΔtΔ�, and r→i - Answers-The correct answer is: r→f=r→i+v¯¯¯→Δt
The graph shows the position of an object in two-dimensional motion. Which of the following statements related to the graph is not correct? - Answers-The correct answer is: You can graphically find the magnitude of the velocity vector using this graph. Suppose you are examining the motion of a train. ri→=25mi^+100mj^rf→=−25mi^+125mj^��→=25��^+100��^��→=−25��^+ 5 ��^ What is the value for Δr→Δ�→? - Answers-The correct answer is: Δr→=−50mi^+25mj^ Which of the following statements is not correct? - Answers-The correct answer is: All these statements are correct. Which of the following is not an example of two-dimensional motion? - Answers-The correct answer is: an astronaut "walking" in space How are the master equations of kinematics with constant acceleration for two- dimensional motion related to the master equations of kinematics for one-dimensional motion? - Answers-The correct answer is: The two-dimensional equations are the same as the one-dimensional equations in two different directions: x and y. Which of the following statements related to two-dimensional motion is not correct? - Answers-The correct answer is: If r→ is multiplied by a positive number, the direction can possibly change. Which of the following motion events is not an example of projectile motion? - Answers- The correct answer is: a hockey puck sliding across an ice rink Which of the following statements best describes speed as a function of time of a projectile launched in the horizontal direction? - Answers-The correct answer is: The speed of the object increases with time. Consider an object in projectile motion. You know xi, yi, yf and vi x. Which of the following general statements best describes how you might find the range of the object?
- Answers-The correct answer is: Use both the equations of kinematics with constant acceleration in the x- and y-direction to solve for the range. The illustration shows the path of the projectile. Which of the following correctly states the formulas for its motion in two dimensions? - Answers-The correct answer is: vix=vcosθviy=vsinθt=viy12(g)R=2v2(cosθsinθ)g=v2gsin2θ How long will it take for a ball to hit the ground if it is dropped from a height of 50 m? - Answers-The correct answer is: 3.2 s How long will it take for a ball, with an initial horizontal velocity of 96 m / s, to hit the ground from a height of 800 m? Also, what is the range of the ball? - Answers-The correct answer is: t = 12.8 s; range = 1,229 m
Which of the following is not a good example of uniform circular motion? - Answers-The correct answer is: a person taking off on an airplane to fly around the world on a path defined by the equator Which of the following is not correct? - Answers-The correct answer is: f = 2T = frequency: the number of revolutions around a circle per second. In a uniform circular motion, the average velocity is a¯¯¯=v2/r Which of the following statements about the derivation of this relationship is not correct. - Answers-The correct answer is: As Δt→0,Δ�→0, (Δr→/Δt)→a→, the instanteneous acceleration. A physicist on a train moving at 10 m / s observes a ball moving at 2 m / s in the same direction as the train's movement. Suppose someone standing still, to the side of the passing train, observes this event. A third person, in a car traveling at 5 m / s in the same direction as the train, also observes the event. Which of the following statements about the velocity of the ball is not correct? - Answers-d. All of these statements are correct. Relative motion is the motion of _____________. - Answers-The correct answer is: an object as described using two different reference frames or coordinate systems A jet is observed by two people. One person is standing in reference frame Q. A second person, in reference frame Q', that moves at a constant velocity, v→, to the right. At t=0, Q' is at the same location as Q. Which of the following statements about this event is not correct? - Answers-b. The position of the jet observed in reference frame Q′ equals the position of the jet observed in reference frame Q plus v. The compass of an airplane indicates that it is flying north at 450 mi/h. The wind velocity is 50 mi/h from the east to the west. The velocity of the airplane relative to the wind is v→A,W. The velocity of the airplane relative to the Earth is v→A,E. The velocity of the wind relative to the Earth is v→W,E. Which of the following statements is correct? - Answers-a. In the reference frame of the wind the plane's motion shifts toward the west. Which of the following is not an example of relative motion? - Answers-c. A plane is traveling at a speed of 500 mi / h. A daredevil is hanging onto one wing of the plane. The plane drops a package. The person flying the plane calculates the velocity of the package. The daredevil also calculates the velocity of the package. A boat is observed by a person standing on the opposite bank of a river. The boat crosses the river with a speed relative to the observer (v→B,O) of 15 m/s. The river has a constant downstream velocity (v→R,O) of 8 m/s. What is the magnitude of the velocity of the boat relative to the river (vB,R)? Also, find the value of θ. - Answers-The correct answer is: v→B,R=17m/s θ=28∘
The compass of an airplane indicates that it is flying south at 150 mi/h. There is a constant 40 mi/h wind blowing the airplane from west to east. The velocity of the airplane relative to the wind is v→A,W. The velocity of the airplane relative to the Earth is v→A,E. The velocity of the wind relative to the Earth is v→W,E. Given this information, what is the correct description for v→A,W? - Answers-The correct answer is: v→A,W= 155 mi/h in the SE direction A person weighing 600 N (mass = 60 kg) when at rest stands on a scale inside a train. The train begins to accelerate horizontally at a rate of 3.5 m / s2. What reading will the scale then give for the weight of the person? Use 10.0 m / s2 as the acceleration due to gravity on the Earth. - Answers-The correct answer is: 600 N An object with mass 5 kg is under a constant force (10i^+20j^) N. Its initial velocity is (−5i^+30j^) m/s. What will be its position 10 seconds later? - Answers-The correct answer is: (50i^+500j^) m Which of the following statements best describes the concept of uniform motion? - Answers-The correct answer is: In the absence of a net force, a moving body continues moving in a straight line with constant speed. An object with a mass of 5 kg is subject to a constant force. Its initial velocity is (−10i^+30j^) m/s. It is expected to be (20i^+10j^) after 10 seconds. What is the force? - Answers-The correct answer is: (15i^−10j^) N Suppose you carve out a small region exactly at the Earth's center and stand inside that region. What would you weigh? Assume the Earth is a perfect sphere and has a uniform density. - Answers-The correct answer is: 0 Which of the following best defines the variables in Newton's second law, F→=ma→? - Answers-The correct answer is: When an object is pushed or pulled, it is subject to a force; this is represented on the left side of the equation. The right side of the equation describes motion, in particular acceleration and kinematics (e.g., how velocity changes with time). The mass is the proportionality constant. Massive objects are sluggish and exhibit slower acceleration for given forces than less massive objects do. Overall, the right side describes motion and it indicates what happens when a force is applied to an object. Which of the following statements best describes an isolated body? - Answers-The correct answer is: An isolated body is neither pushed nor pulled by unbalanced forces and maintains a uniform, or steady, motion. Newton's third law is sometimes counterintuitive. For instance, it may be difficult to accept that when a car collides with a sport-utility vehicle (SUV), the small car pushes back with equal force on the large SUV. Given that Newton's third law is correct, which of the following is correct, and what does it suggest?Note: S = SUV, C = car - Answers- The correct answer is: Both A and B.
Diagram A shows a weight on an incline. Assume that the system has no friction. The x- and y-axes are also shown. From the orientation of the axes, ∑ F→y=0, there is no motion in the y-direction. To solve for N→, you have to determine the value of W−→(mg). For reference, diagram B shows the same incline with the x- and y- components of weight labeled. Which of the following is the equation for N→? - Answers-The correct answer is: N→=mg→ cosθ When drawing a free-body diagram, ____________. - Answers-The correct answer is: consider one object and all the forces acting on that object Which of the following statements regarding drag force and terminal speed is not correct? - Answers-The correct answer is: The drag coefficient is a unitless, proportionality constant, of the drag force that depends on the size, shape, weight, and texture of the object. If a wooden block is pushed across a table, the resulting frictional force will be__________. - Answers-The correct answer is: Opposite to the direction of the force on the block. The diagram shows a wooden block on an inclined ramp. Which of the following statements regarding this example is correct? - Answers-The correct answer is: All of the above. Which of the following best defines the terms kinetic friction and static friction? - Answers-The correct answer is: Kinetic friction is the force between two moving objects that resists their relative motion. Static friction is the force between two stationary objects that resists their relative motion. A wooden block is pushed across a table with an increasing force as shown on the horizontal axis. The frictional force is shown on the vertical axis. Which of the following statements is incorrect? - Answers-The correct answer is: A maximum force can be applied to the block, and it is reached at the point fs,max. This maximum force settles down to fk=μkN once the block is in motion. The force diagram shows a block of wood on an incline. Formulas for Wx and Wy are shown. Using Newton's second law, we can derive the following equations: ∑Fx=max −fs+mgsinθ=0fs=+mgsinθfs=+mgsinθcfs,max=μsmgcosθc Which of the following statements regarding these equations is not correct? - Answers- The correct answer is: The value of μs increases proportionally to θ. 12CρAv Which of the following statements regarding this equation is not correct? - Answers-The correct answer is: The term v is the volume of the fluid and its unit is meters cubed.
The drag force, Fdrag, depends on several variable factors. Which of the following factors does not affect the drag force on an object? - Answers-The correct answer is: The mass of the object, m, moving through a fluid. A block of wood is pushed across a table. Which of the following characteristics of the wood block most affects the force of friction in this scenario? - Answers-The correct answer is: The weight of the wood block. The diagram shows a block of wood on a ramp. The ramp is slowly being raised, so that θ is increasing. Forces at work on the object include the normal force, N→, the weight of the object, W−→, and the force of static friction, f→s. Which of the following statements regarding this example is not correct? - Answers-The correct answer is: The magnitude of static friction depends on the magnitude of the other forces. As θ increases, f→s decreases, until the critical angle is reached and the woodblock breaks free. The following diagram shows a bucket containing water moving in uniform circular motion. The normal force, N→, and the weight of the water W−→(mg→), are shown. Direction is also indicated. Which of the following equations involving the value of N→ is correct? - Answers-The correct answer is: All of the above. The following diagram shows a physical diagram and a force diagram of a conical pendulum. The x-axis and y-axis are also shown. The ball is moving in uniform circular motion. Which of the following equations contains the correct equation to solve for forces in the x-direction? - Answers-The correct answer is: T sin θ=mv2/r The diagram shows a physical diagram and a force diagram of a conical pendulum. The x-axis and y-axis are also shown. The ball is moving in uniform circular motion. Which of the following equations contains the correct equation to solve for forces in the y- direction? - Answers-The correct answer is: T cos θ−mg= Which of the following statements regarding uniform circular motion is not correct? - Answers-The correct answer is: In calculating the maximum speed of a Ferris wheel, you must account for the lightest possible rider, because that rider could accidentally fly off the wheel at slower speeds than heavier riders. Which of the following statements correctly describes the physical laws of uniform circular motion? - Answers-The correct answer is: In uniform circular motion, objects accelerate toward the center of the circle, so there must be a centripetal force. The following diagrams show a bucket of water in uniform circular motion. Imagine swinging the bucket in a vertical circle so that none of the water leaves the bucket, even when it is directly overhead. The first diagram is a physical diagram of the bucket in motion. The second is a force diagram of the same bucket. The positive direction is indicated for the force diagram. Which of the following statements regarding forces at work on the water is correct? - Answers-The correct answer is: There is the contact, or
