Physics 103, Midterm Exam 1, Spring 2005 Instructions 1. Use X5 answer sheet 2. Use No. 2 pencil 3. Fill in your Last Name, First Name, MI 4. Fill in your 10 digit UW Student ID (Very Important) 5. Work out the problems, draw pictures, … on this exam book, you may use the back side as needed - You must circle your final answers on this exam book and fill in the corresponding mark on the X5 answer sheet. 6. You must write your name, UW Student ID and circle your lab instructor name on this exam book. 7. You must turn in this exam book 8. Do not spend too much time on any particular problem - you need to answer all questions Name: 10 Digit UW Student ID: Lab Instructor: Tony Barnes Don Brandl Josh Kogut Hye-sung Lee Steve Trier Carl Vuousalo Comments: 1) Tiger Woods and Vijay Singh tee off at Augusta by striking their golf balls. The balls first hit the course at exactly the same spot and then make it into the hole. From this observation we can conclude that: A. The speeds at which their golf balls left the club are identical. B. The angles at which their golf balls left the club are identical. C. The maximum heights their golf balls reached are identical. D. The vertical components of the velocities with which the golf balls left the club are identical. E. None of the above. 2) The position versus time for a particle is shown in the figure below. During which period is the acceleration positive? A. 0.1s to 1.9s B. 2.1s to 3.9s C. 4.1s to 4.9s D. 5.1s to 6.9s E. Acceleration is zero during all the periods A-D 3) The drivers of an 18-wheeler (10000 kg), a pickup truck (2000 kg) and a VW bug (1000 kg) are driving along neck-to-neck on a straight road at 120 km/h on a three lane highway, when they see a road block. If all three drivers slam on the breaks simultaneously and come to stop within 1 meter of the roadblock, what can you conclude? A. The magnitude of acceleration of the 18-wheeler is the greatest. B. The magnitude of acceleration of the pickup truck is less than that of the 18- wheeler but more than that of the VW bug. C. The magnitude of acceleration of the VW bug is the least. D. A, B and C are true. E. The magnitude of acceleration of all three vehicles is the same 4) The same force F is exerted in the two cases (a) and (b) shown below. Which of the following statements is true? A. The normal force and the frictional forces exerted by the ground on the sled, are the same for both cases (a) and (b). B. The normal force and the frictional forces exerted by the ground on the sled, are higher for the case (a) compared to the case (b). C. The normal force and the frictional forces exerted by the ground on the sled, are smaller for the case (a) compared to the case (b). D. The normal force is the same for both cases but the frictional force is smaller for the case (a) compared to the case (b). E. The normal force is the same for both cases but the frictional force is higher for the case (a) compared to the case (b). 5) The severity of injury depends on the speed at which one strikes the ground. If on the Earth a person can safely land jumping unaided from 10 feet up, from how high can the same person jump when he/she is on the Moon (Acceleration due to gravity on the surface of Earth is six times that on the Moon). A. 10 feet B. 30 feet C. 60 feet D. 120 feet E. 360 feet 6) A projectile of mass M and another of mass 5M were launched at the same time at 15 o and 75 o with respect to the ground, at the same speed. Which of the following statements is true? A. Projectile with mass M strikes the ground 5 times sooner than the one with mass 5M B. Projectile with mass M strikes the ground 5 times farther than the one with mass 5M C. Both projectiles strike the ground at the same time. D. Both projectiles strike the ground at the same distance. E. The answer depends on the mass and speed 7) A skier of mass 50 kg is coming down a hill with varying slope. At what point is his frictional force half as much as it will be when he reaches the hoizontal surface near the ski lift? A. When the slope is 30 o to the horizontal B. When the slope is 45 o to the horizontal C. When the slope is 60 o to the horizontal D. At the top of the hill E. The frictional force is the property of the surfaces and will remain the same all the way down the hill. 8) A tightrope walker is at the center of the rope tied between two poles. The rope makes an angle of 4.8 o with respect to the horizontal. The tension in the string will be A. equal to one half the weight of the tightrope walker. B. equal to the weight of the tightrope walker. C. equal to twice the weight of the tightrope walker. D. equal to six times the weight of the tightrope walker. E. not possible to determine without knowing the distance between the poles. 9) Three children Aaron (20 kg), Beth (25 kg) and Charlie (30 kg) take off on sleds at the same speed from the top of a hill. Who will reach the bottom first? (µ k = 0.15) A. Aaron B. Beth C. Charlie D. All of them reach the bottom at the same time E. Answer depends on the unknown mass of the sleds used 10) Bob has two balls. He releases one ball from a platform of height H. Just as that ball strikes the ground, he releases the next ball from the same height. Assuming that the first ball bounces perfectly,( i.e., reversing only the direction of its velocity when it strikes the ground), at what height from the ground do the balls strike each other? A. H/4 B. H/3 C. H/2 D. 3H/4 E. None of the above 11) A massive wooden crate (M) is on a wooden floor. A horizontal force is exerted on the crate till the static frictional force is just overcome. If that force is maintained for a period of time (t), how far is the crate displaced? (Coefficients of static and kinetic friction are µ s and µ k . Acceleration due to gravity is g.) A. 1 2 gt B. k C. µ s gt 2 D. 1 ( s − k ) E. 2 s gt 2 12) A fireman, 50.0 m away from a burning building, directs a stream of water from a ground level fire hose at an angle of 30.0° above the horizontal. If the speed of the stream as it leaves the hose is 40.0 m/s, at what height will the stream of water strike the building? A. 2.5 m B. 4.9 m C. 9.8 m D. 18.6 m E. 37.2 m 13) A boy uses a slingshot to propel a stone of mass 0.1 kg upwards at 45 0 with respect to the horizontal across a river. Neglecting any air resistance, about 1 second after the stone leaves the slingshot, the direction of its acceleration is A. > 45 0 to horizontal B. < 45 0 to horizontal C. along the direction of its motion D. opposite the direction of its motion E. downwards 14) A driver slams on the brakes as soon as he sees a roadblock on a highway. If he is traveling at 60 mph and comes to a stop in 3 s, how far did the car move before coming to a full stop? A. 10 m B. 20 m C. 30 m D. 40 m E. 50 m 15) Ann, Beth and Carly can swim equally fast. In a competition to swim across a river that is flowing twice as fast as the girls can swim, Ann heads 45 o upstream, Beth heads straight across and Carly points 45 o downstream, all doing the best job that they can. Which of the following statements is true? A. Ann reaches the opposite bank directly across the starting point. B. Ann and Carly reach the opposite bank, at different places, at the same time, but later than Beth. C. The order in which they reach the opposite bank is Ann, Beth and Carly. D. The order in which they reach the opposite bank is Carly, Beth and Ann. E. Ann, Beth and Carly reach the opposite bank at the same time. 16) Peter throws a 1-kg rock 10 m vertically up while standing on a ladder at a height of 10 m. Paul throws a 2-kg rock vertically upward, from the ground level, to twice the distance as Peter did. The speed of Peter’s rock compared to Paul’s rock when they eventually land on the ground in their free fall is, A. quarter as much. B. half as much. C. the same D. twice as much E. four times as much 17) A tennis ball launching machine is to be adjusted for maximum range. What angle should the balls be launched if the launch speed remains constant? A. 15 o above horizontal. B. 30 o above horizontal. C. 45 o above horizontal D. 60 o above horizontal E. 90 o above horizontal 18) A car has a maximum acceleration of 3 m/s 2 . What would its maximum acceleration be while towing a second car with twice its mass? A. 2.5 m/s 2 B. 2.0 m/s 2 C. 1.5 m/s 2 D. 1.0 m/s 2 E. 0.5 m/s 2 19) A cheetah can run at approximately 100 km/hr and a gazelle at 80.0 km/hr. If both animals are running at full speed, with the gazelle 70.0 m ahead, how long before the cheetah catches its prey? A. 12.6 s B. 25.2 s C. 6.30 s D. 10.7 s E. None of the above 20) In the picture below (a), (b) and (c) represent velocity versus time graphs and (d), (e), and (f) represent acceleration versus time graphs. Which of the following graph pairs are matching correctly? A. (a) and (e) B. (b) and (d) C. (c) and (f) D. All of the above E. None of the above Sridhara Dasu exam1s05