PHY201 Practice Exam #1

1. (3 pts) The person credited with the introduction of the modern version of the scientific method is (a) Pythagoras. (b) Aristotle. (c) Bacon. (d) Galileo. (e) Zeno.
2. (3 pts) An object is released from rest at the top of a frictionless incline. Which of the following best characterizes the speed and the magnitude of the acceleration of the object while it slides down the incline? (a) Both the speed and the magnitude of the acceleration remain constant. (b) The speed increases and the magnitude of the acceleration decreases. (c) The speed increases and the magnitude of the acceleration remains constant. (d) Both the speed and the magnitude of the acceleration increase. (e) The speed decreases and the magnitude of the acceleration increases.
3. (3 pts) Consider three vectors, A, B, and C. The tails of B and C are at the same location. The tail of A is located at the tip of C and the tip of A is at the tip of B (You may need to draw this on a piece of paper). Which of the following statements is true? (a) A = B + C. (b) A = B - C. (c) A = B x C. (d) A = B . C. (e) All of the above, or maybe some of the above, but always none of the above.
4. (3 pts) An object is shot from the back of a truck moving at 30 mph on a straight horizontal road. The gun is aimed upward, perpendicular to the bed of the truck. The object falls (a) in front of the truck. (b) behind the truck. (c) on the truck. (d) It depends upon the speed of the truck. (e) It depends upon the value of g.
5. (3 pts) A projectile is fired from a cannon at some angle with respect to the ground. In the absence of air resistance the path of the object will be that of a parabola. Which of the following is true? (a) The acceleration of the object is directed upward while the object is moving away from the earth, and the acceleration is directed downward while the object is moving toward the earth. (b) The acceleration of the object is zero, since there is no air resistance. (c) The acceleration of the object is always directed away from the surcface of the earth. (d) The acceleration of the object is always directed toward the surface of the earth. (e) The acceleration of the object is always directed parallel to the surface of the earth (in the direction of the objects horizontal motion).
6.(3 pts) A lead block is suspended by a string which is held by your hand. The reaction to the force of gravity on the block is the force exerted by the (a) string on the block. (b) block on the string. (c) string on the hand. (d) hand on the string. (e) block on the earth.
7. (3 pts) A block is suspended on a spring scale in an elevator. The scale shows the highest reading when the elevator (a) moves upwards with increasing speed. (b) moves upwards with decreasing speed. (c) remains stationary. (d) moves downwards with increasing speed. (e) moves downwards at constant speed.
8. (3 pts) An satellite has a single (constant) force of 1000 N applied to it. The force is applied for 2 sec and then a second force of 1000 N is applied to the satellite in the exact opposite direction of the first force. Which of the following best characterizes the motion of the satellite? (a) The satellite accelerates for the first two seconds, and moves at a constant velocity afterwards.. (b) The satellite accelerates for the first two seconds, and then comes to an immediate stop. (c) The satellite accelerates for the first two secondes, and then comes to a gradual stop. (d) The satellite accelerates for the first two seconds, and then accelerates even more afterwards. (e) The satellite maintains a constant acceleration at all times.
9. (3 pts) A graph of the position of an object as a function of time produces a straight line with a constant positive slope. What is the interpretation of the slope? (a) The slope is the postion of the object after 10 seconds. (b) The slope is the time required for the object to reach a position of 10 meters. (c) The slope is the speed of the object. (d) The slope is the acceleration of the object. (e) Since the slope is a mathematical quantity, it has no meaning.
10. (3 pts) In which direction should the centripital force be placed on a free body diagram? (a) Toward the center of the circular path of the object. (b) Away from the center of the circular path of the object. (c) Up. (d) In the direction of motion of hte object (it is what keeps the object moving). (e) None of the above.
11. (3 pts) A person rides a ferris wheel which executes uniform circular motion in a vertical plane. At what point will the person have the smallest apparent weight? (a) Since the motion is uniform, the apparent weight of the person will always be the same (but notequal to zero). (b) Since the motion is uniform, the apparent weight of the person will always be equal to zero. (c) At the point cosest to the ground. (d) At the point furthest from the ground. (e) None of the above.
12. (3 pts) A baseball is caught by a person. While catching the ball, the person may move their hand backwards. What is the effect does moving the hand backwards have on the force felt by the catchers hand (as compared to catching the ball without a backward movement of the catching hand)? (a) It depends on the mass of the baseball. (b) It depends upoon the mass of the person's hand. (c) The force is increased. (d) The force is decreased. (e) There is no effect on the force.
13. (3 pts) The planet jupiter is about 300 times more massive than the earth, yet on its surface you would weigh only about 3 times as much. This is probably because (a) your mass is 100 times less on jupiter. (b) jupiter is significantly farther from the sun. (c) the radius of jupiter is 10 times greater than the earth's radius. (d) the radius of jupiter is 100 times greater than the earth's radius. (e) jupiter has a non-uniform composition.
14. (3 pts) Ptolemy's model of the universe placed the earth at the center of a series of spheres, each of which governed the motion of a planet, the moon, the sun, or the stars. Copernicus modified this model by placing (a) Kepler at a party at Brahe's house. (b) the sun at the focus of an ellipse. (c) the sun at the center of the universe. (d) the axis of rotation for the sun roughly at the location of Venus. (e) Pluto near the edge of the solar system.
15. (3 pts) Two objects move in a circle about the same center. Object 1 has a mass of 10 kg, a constant speed of 3 m/sec, and moves at a radius of 1 m. The second mass is 1 kg, also moves at a constant speed of 3 m/sec, and is at a radius of 2 m. The object with the largest accelration is (a) Object 1. (b) Object 2. (c) They both have the same non-zero accelration. (d) They both have zero acceleration. (e) There is not enough information provided to answer this question.
16 (4 pts). A boat travels at a constant velocity of vB = 1 m/sec j. It heads directly across a flowing river for which the speed of the current is vC = - .05 m/sec i. According to an observer standing on the shore, what is the velocity of the boat? (a) .05 m/sec i + 1 m/sec j. (b) - .05 m/sec i + 1 m/sec j. (c) .05 m/sec i - 1 m/sec j .(d) 1 m/sec j. (e) 1 m/sec.
17 (4 pts.). An object rests on a frictionless incline, the incline having an angle of 30o with respect to the horizontal. When an horizontal force of 57.7 N is applied to the object, it is found that the object can be held motionless. If the mass of the object is 10 Kg, what is the normal force (use g = 10 m/sec2 for convenience)? All answers are in Newtons. (a) 100. (b) 100 cos 30o. (c) 100 sin 30o. (d) 100/cos 30o. (e) 100/sin 30o.
18 (4 pts). A baseball is hit straight up and is caught by the catcher 2.0 sec later. The maximum height of the ball during this interval is (a) 4.9 m. (b) 7.4 m. (c) 9.8 m. (d) 12.6 m. (e) 19.6 m.
19. (4 pts.) As a result of forces applied to it, a satellite changes it's speed from 1000 m/sec to 750 m/sec in 10 sec. If the mass of the rocket is 20 kg, the magnitude of the force cusing this change is (assume linear motion without a change in direction)? (a) 250 N. (b) 500 N. (c) 1000 N. (d) 2000 N. (e) 3000 N.
20. (4 pts) Three masses are arranged so that mass #1 is at the origin and has a mass m1, mass #2 is at x = 5 meters, y = 0 meters and has a mass m2, and mass #3 is at x = 5 meters, y = 5 meters and has a mass m3. What is the gravitational force on m2? You might need to make a drawing of this. (a) (G m1 m2 m3 )/25. (b) (G m1 m1)/25 + (G m2 m3)/25. (c) (G m1 m2)/25 i + (G m2 m3)/25 j. (d) -(G m1 m2)/25 i + (G m2 m3)/25 j. (e) None of the above.
21 (20 pts.). An object is thrown toward the ground from the top of a building with an angle of 30o with respect to the building. The ball is thrown with a speed of 10 m/sec. The height of the building is 50 m. (a) What is the horizontal distance (range) the object travels? (b) What are the components of the velocity when it hits the ground?
22 (20 pts.). A block (block 1) is located on an incline. At the top of the incline there is a massless pulley. A string is attached to the block on the incline, the string is placed on the pulley, and then a second block (block 2) is connected to the free end of the string so that the second block hangs vertically off the end of the incline. The mass of block 2 is 10 kg, and the coefficient of kinetic friction is 0.2. If block 1 slides with a constant velocity down the incline, what is the mass of block 1?
Answer Key:1.D; 2.C; 3.B; 4.C; 5.D; 6.E; 7.A; 8.A; 9.C; 10.E; 11.D; 12.D; 13.C; 14.C; 15.A; 16.B; 17.D; 18.A; 19.B; 20.D
Practice Test #2

1 (3 pts). During the course of this term, we will examine the properties of simple physical systems in our study of physics. Which of the following best describes the usefulness of these systems? (a) The simple systems have very little value; physicists just like to think about stupid things. (b) Although the systems may be simple, the fundamental laws of nature work as well for simple systems as they do for complicated systems. The chances of extracting these fundamental laws from very complicated systems is very small. (c) Although the characteristics of these simple systems have no application to more interesting systems, the simple systems form a useful approximation to the real world. (d) Simple systems are important because the behavior can be modeled using simple equations. Simple equations cannot exhibit maximal complexity. (e) Funding agencies will only give grants for studies of simple systems.
2 (3 pts). An object moves in the following way: From t = 0 sec to 3 sec, v = -2 m/sec; from t = 3 sec to 5 sec, v = 1 m/sec; and from t = 5 sec to 7 sec, v = 5 m/sec. If the object started at x = 0 m, what is the location of the object after 7 sec. Assume the motion is one dimensional along the x axis. You might want to graph this. (a) -2 m. (b) 0 m. (c) 2 m. (d) 4 m. (e) 6 m.
3 (3 pts). An object weighing 10 N executes free fall in the absence of air resistance. A force of 10 N is suddenly applied in the opposite direction to the direction of the objects motion. As a result, the object will (a) come to an immediate stop. (b) gradually come to a stop. (c) accelerate toward the earth, but with an acceleration less than 9.8 m/sec2. (d) accelerate toward the earth, but with an acceleration more than 9.8 m/sec2. (e) move with a constant velocity.
4 (3 pts). An object is dropped from the top of a building. The vertical position of the object is given by the relationship y=at+bt^2, where y is measured in meters and t^2 means t squared. What are the units on "a" and "b" respectively? (a) m, m. (b) m, m/sec. (c) m, m/sec². (d) m/sec, m/sec. (e) m/sec, m/sec².
5 (3 pts). An object is shot from the back of a truck moving at 30 mph on a straight horizontal road. The gun is aimed upward, perpendicular to the bed of the truck. The object falls (a) in front of the truck. (b) behind the truck. (c) on the truck. (d) It depends upon the speed of the truck. (e) It depends upon the value of g.
6 (3 pts). The best measure of the inertia of an object is the object's (a) weight. (b) mass. (c) volume. (d) color. (e) width.
7 (3 pts). An ball is thrown vertically up (assume no air resistance). Assume the ball leaves the hand at a point A. At it's highest point (point B) the object stops momentarily, and then falls back to it's original location (point C). When is the object's acceleration 9.8 m/sec2 toward the surface of the earth? (a) From A to B. (b) At B. (c) From B to C. (d) At all points in the motion except B, since it has stopped at this point. (e) At all points in the motion.
8 (3 pts). When an oceanliner makes a course correction, it can take a mile or two for the direction change to occur. Why is this? (a) Because of the large retarding force exerted by the water on the ship. (b) Because rudders tend to be smooth and the water slips off too easily. (c) Because a ship has a large amount of inertia. (d) Because when the ship exerts a force on the water, the water exerts an equal and opposite force, thereby keeping the ship moving in a straight line. (e) Because the ship is in free fall, and therefore must always have the same acceleration (both magnitude and direction).
9 (3 pts). A car goes around a right hand corner at 30 mph. This particular car has a frictionless bench seat, and as a result, the person sitting on the seat (whose weight is 150 lb) slides to the left side of the car (the person is not wearing a seatbelt). While the person is sliding, the force which pushes them to the left is of magnitude (a) 0 lb, since there is no force doing this. (b) 150 lb, since a force equal to the weight is required to move the person. (c) greater than 150 lb, since a force larger than the weight is required to produce an acceleration. (d) less than 150 lb, so that the unbalanced weight can slide the person to the left. (e) 30 lb, to balance the speed.
10 (3 pts). When a person stands with two feet on a scale, the scale reads 500 N. When the person lifts one foot, the scale reads (a) less than 500 N. (b) more than 500 N. (c) 500 N. (d) It depends upon the size of the persons feet. (e) None of the above.
11 (3 pts). A free falling object has a constant acceleration of 9.8 m/sec^2. This means that (a) the body falls 9.8 meters each second. (b) the body falls 9.8 m during the first second. (c) the speed of the body changes by 9.8 m/sec during each second. (d) the acceleration of the body increases by 9.8 m/sec^2 during each second. (e) the acceleration of the body decreases by 9.8 m/sec^2 during each second.
12 (3 pts). An object executes uniform circular motion (ie, a constant speed and constant radius). The acceleration of the object is (a) zero, since the speed is constant. b) a constant in magnitude, directed away from the center of the circle. (c) a constant in magnitude, directed toward the center of the circle. (d) 9.8 m/sec^2. (e) None of the above.
13. (3 pts) The model of the universe presented by Ptolemy (2nd century) was accepted for centuries before being replaced by a better theory. In order to account for the motions of celestial objects, Ptolemy utilized (a) the Newman Theorem. (b) celestial spheres. (c) Kepler's Laws. (d) the Universal Law of Gravitation. (e) the concept of Retrogradation.
14. (3 pts) An object weighs 20 N at the surface of the earth. At a height of one earth radius above the earth's surface, the object weights (in Newtons) (a) 0.0. (b) 5.0. (c) 10 N. (d) 15 N. (e) 20 N.
15. (3 pts) Two identical objects move in uniform circular motion in circles of different diameter. Object 1 moves in a circle of larger diameter, while object 2 moves in a circle of smaller diameter. In order that the magintude of the force on each be the same, (a) object 1 must move faster. (b) object 2 must move faster. (c) both objects must move at the same speed. (d) There is no force under the conditions desribed. (e) There is not enough information given to answer this question.
16 (5 pts). An object has an acceleration of zero. Which of the follwoing best desribes the number of forces which act on that object? (a) 0. (b) 1. (c) 2. (d) 3. (e) There is not enough information given to answer this question.
17 (5 pts). A rocket of mass 1000 kg has a load of fuel (mass of the fuel = 50 kg). The mass of the fuel is not included in the 1000 kg rocket mass. The fuel is ejected form the back of the rocket at 100 m/sec. As a result, the rocket will move with a speed (in m/sec) (a) 1.0. (b) 2.0. (c) 3.0. (d) 4.0. (e) 5.0.
18. (5 pts.) Two billiard balls of equal mass are moving with equal but opposite velocities of magnitude 5 m/sec and they collide head on into a peice of bubble gum to which they both stick. What will their mutual speed be after the collision? (a) 0 m/sec. (b) 5 m/sec. (c) 10 m/sec. (d) 20 m/sec. (e) 30 m/sec.
19 (5 pts). A rock climber (mass of 120 kg) is hangfing freely from a rope off the side of a cliff. A winch is used to lower the person with an acceleration of 2.8 m/sec2. While this is happening, the tension in the rope is (a) 336 N (b) 840 N. (c) 1176 N. (d) 1512 N. (e) Not enough information given.
20. (5 pts) An object moves at constant speed in a vertical circle of radius 10 m. The speed of the object is 2.0 m/sec. As you draw this figure, make the upward vertical direction be the +y direction, and the direction to the right of this axis be the +x. What is the acceleration of the object at the point on the circle which crosses the +x axis? (a) 0.4 j. (b) - 0.4 j. (c) 0.4 i. (d) - 0.4 i. (e) 0.
21 (20 pts). A football is kicked at ground level with a speed of 9.8 m/sec at an angle of 30o to the horizontal. (a) How much later does it hit the ground? Ignore air resistance. (b) How far from the kicker does the football land?
22. (20 pts). Two blocks (m1 = 3 kg, m2 = 4 kg) are suspended by a string placed over a pulley. The string hangs vertically on both sides of the pulley, with block #1 hanging on the left side and block #2 hanging on the aright side. A force of 3 N is applied to m2 in the vertical upward direction. What is the acceleration of the system? For convenience in this calculation, use g = 10 m/sec2. You might need to draw a picture of this.
Answers: 1.B; 2.E; 3.E; 4.E; 5.C; 6.B; 7.E; 8.C; 9.A; 10.C; 11.C; 12.C; 13.B; 14.B; 15.A; 16. E; 17.E ; 18.A ; 19.B; 20.D