UNIVERSITY OF SASKATCHEWAN Department of Physics and Engineering Physics

Transcription

1 UNIVERSITY OF SASKATCHEWAN Departent of Physics and Engineering Physics 017 Saskatchewan High School Physics Scholarship Copetition Wednesday May 10, 017 Tie allowed: 90 inutes This copetition is based on the Saskatchewan High School Physical Science 0 and Physics 30 curricula. INSTRUCTIONS: 1. You should have a test paper and an OMR (Optical Machine Readable) or Coputer scan sheet. The test paper consists of 8 pages, including this cover page. The student should check that the test paper is coplete.. Enter your nae and school on the OMR sheet. 3. Enter your personal inforation on the table below. 4. At the end of the exaination only this cover page and the OMR sheet ust be subitted. 5. All questions are of equal value. 6. Marks are awarded for correct answers only. No arks will be deducted for wrong answers. 7. Calculators ay not be used. (None of the questions require the use of a calculator.) PLEASE PRINT THE FOLLOWING INFORMATION Nae: School: Physics Teacher: Hoe Address: Postal Code: Telephone: Eail address: Page 1 of 8

2 Saskatchewan High School Physics Scholarship Copetition May 10, 017; Page FOR EACH OF THE FOLLOWING QUESTIONS ENTER THE MOST APPROPRIATE RESPONSE ON THE OMR SHEET. Note: In all the questions the sybol g denotes the agnitude of the acceleration due to gravity on the Earth s surface. 1. The width of a rectangular field is easured to be 7.0 and its length is easured to be We calculate the area of the field by ultiplying its width by its length and find that our calculator display reads 3, The correct way to express the area to the appropriate nuber of significant figures is Which stateent is correct regarding heat transfer by convection? It requires no significant displaceent of olecules. It cannot be an effective heat transfer echanis in a solid. It is the only possible heat transfer echanis in a vacuu. It does not occur in liquids. 3. The specific heat capacity of substance A is greater than that of substance B. Both A and B are at the sae initial teperature. Equal aounts of energy are added to each substance. Assuing that no elting or vaporization occurs, which of the following can be concluded about the final teperature of substance A, T A, and the final teperature of substance B, T B? T A > T B. T A = T B. T A < T B. We need ore inforation to ake a conclusion. 4. The diagra shows two rods, one ade of aluinu and the other ade of steel. The coefficient of linear expansion for aluinu is about two ties that of steel. The two rods are of equal length when they are at the sae initial teperature. Each rod is attached at one end to an iovable wall, as shown. The dashed line shows the idpoint between the ends of the rods when they are at the sae initial teperature. The teperatures of the two rods is increased, both by the sae aount, until the gap between the rods is closed. Where do the rods eet when the gap is closed? The rods eet exactly at the idpoint. The rods eet to the right of the idpoint. The rods eet to the left of the idpoint. We need to know the actual lengths of the rods to decide. Aluinu Midpoint Steel Page of 8

3 Saskatchewan High School Physics Scholarship Copetition May 10, 017; Page 3 5. The frequency of a periodic wave travelling on the surface of water is 0. Hz. What is the tie between wave crests passing a certain point? (F) seconds. 4 seconds. 5 seconds. 0. seconds. 0.5 seconds. Cannot be deterined without knowing the speed of the wave. 6. A string (e.g. a guitar string) is stretched between two fixed points. When the string is ade to vibrate, the lowest (fundaental) frequency of vibration is 100 Hz. When it is ade to vibrate so that there are two nodes between the ends, as shown in the diagra, the frequency of vibration is 300 Hz 00 Hz 150 Hz 50 Hz 33 Hz 7. Which one of the following is an exaple of a longitudinal wave? Waves on the surface of water. Waves travelling up and down a guitar string. Light waves. Sound waves. X-rays. 8. An object, represented by the arrow in the diagra, is placed half way between the focal point (labeled F) of a spherical concave irror and the center of curvature (labeled C) of the irror. The iage of the arrow will be Virtual and upright. Virtual and upside down. Real and upright. Real and upside down. No iage will be fored. C F f 9. For the situation described in question 8, the concave irror has a focal length f. What is the agnitude of the distance between the iage and the irror? f 3 f 5 f f 3 f (F) The iage will be an infinite distance away. Page 3 of 8

4 Saskatchewan High School Physics Scholarship Copetition May 10, 017; Page A sound wave is produced under water. The sound travels to the surface of the water and soe of the sound is transitted into the air. The speed of sound in water is 1450 /s and speed of sound in air is 330 /s. As the sound passes fro water into air, the effect on the frequency of the sound, f, and on the wavelength of the sound,, is f and reain unchanged. f reains unchanged, but decreases. f reains unchanged, but increases. f increases, but decreases. f decreases, but increases. 11. The graph shows how the index of refraction of glass depends on wavelength. A ray of light containing both red and blue wavelengths is incident on a parallel-sided glass block. Which of the diagras below show the ost likely paths of the colours through the block? n (n) 1. An object is placed 40 c fro a diverging lens which has focal points that are 10 c fro the lens. The iage fored by the lens is (F) real, inverted and saller than the object. real, inverted and larger than the object. real, upright and saller than the object. virtual, inverted and saller than the object. virtual, upright and larger than the object. virtual, upright and saller than the object. Page 4 of 8

5 Saskatchewan High School Physics Scholarship Copetition May 10, 017; Page A sall bob contains an internal clock so that it is set to explode 5 s after the rocket in which it is located is launched. Very quickly after launch fro Earth, the rocket reaches a speed of 0.99c. c is the speed of light ( /s). According to an observer on Earth, approxiately how far away fro Earth will the rocket explode? It will explode at a distance of about fro Earth. It will explode at a distance uch less than fro Earth. It will explode at a distance uch greater than fro Earth. There is not enough inforation given to decide. 14. A etal surface is illuinated with blue light and electrons are ejected fro the surface at a certain rate, and with each electron having a certain aount of energy. If the intensity of the blue light is increased, what happens to the ejected electrons? Electrons are ejected at the sae rate, but with ore energy per electron. Electrons are ejected at the sae rate, but with less energy per electron. Electrons are ejected at an increased rate, and with ore energy per electron. Electrons are ejected at an increased rate, with no change in the energy per electron. Electrons are ejected at an increased rate, with less energy per electron. 15. In the radioactive decay of an unstable nucleus a particle is eitted fro the nucleus. In this process what changes take place in the nucleus? The nuber of protons decrease by one, and the nuber of neutrons increase by one. The nuber of protons increase by one, and the nuber of neutrons decrease by one. The nuber of protons decrease by one, and the nuber of neutrons do not change. The nuber of neutrons decrease by one, and the nuber of protons do not change The nuber of protons decrease by two, and the nuber of neutrons decrease by two In a nuclear reactor, one of the reactions that take place is 9 U n 54Xe38Sr neutrons. The nuber of neutrons produced by this reaction is one. two. three. four. five. 17. A stone, with ass, is thrown straight up with initial speed v o and it reaches a height h. A second stone, with ass, is thrown straight up with initial speed v o. We ay ignore air resistance. What is the height reached by the second stone? 1 h h h h 4h 18. Two cars, A and B, start fro rest and each car aintains a constant acceleration. Car A has acceleration a A and car B has acceleration a B. In the sae elapsed tie car A travels ties further than car B. Which of the following is true concerning the accelerations of the two cars? aa ab aa ab aa 4aB aa ab aa ab Page 5 of 8

6 Saskatchewan High School Physics Scholarship Copetition May 10, 017; Page An object of ass is suspended fro the ceiling by eans of a string. The force of gravity pulls downward on the object. Consider this to be the action force in Newton s third law. The reaction force is the string pulling upward on the object, with agnitude g. the ceiling pulling upward on the string, with agnitude g. the string pulling downward on the ceiling, with agnitude g. the object pulling downward on the string, with agnitude g. the object pulling upward on the Earth, with agnitude g. 0. The figure shows the trajectory of a ball. Air resistance is ignored. Point A is where the ball is at its highest above the ground. Point B is where the ball is descending to the ground. Which stateent is correct? A B At point A the ball s velocity is zero, but its acceleration is not zero. At point A the ball s velocity is not zero, but its acceleration is zero. At point A the ball s speed is less than at B, but its acceleration is greater than at B. At point A the ball s speed is less than at B, but its acceleration is saller than at B. At point A the ball s velocity and acceleration are perpendicular to each other. 1. A horizontal force accelerates a box which is on a horizontal surface. There is friction between the box and the surface. The resulting acceleration of the box is constant. All conditions reain the sae with the exception that the agnitude of the horizontal force is doubled. What happens to the box s acceleration? It increases to exactly double its original value. It increases to ore than double its original value. It increases to less than double its original value. It increases to nearly four ties its original value. It decreases.. The net work expended on a car to accelerate it fro 0 to 30 /s is less than that required to accelerate the car fro 30 /s to 60 /s. equal to that required to accelerate the car fro 30 /s to 60 /s. ore than that required to accelerate the car fro 30 /s to 60 /s. The answer depends on the tie taken to achieve the change in speed. Page 6 of 8

7 Saskatchewan High School Physics Scholarship Copetition May 10, 017; Page 7 3. The pilot of a plane pulls out of a dive by flying in a vertical circle of radius R as shown in the diagra. The speed of the plane as it flies through this partial circle is constant and has agnitude V. The pilot of the plane has ass. What is the agnitude of the force exerted on the pilot by his seat at the lowest point in the circle? V g R V g R V R g V R g R V 4. A pendulu bob, of ass, is suspended fro a string of length L. The bob is pulled to one side so that it is a height L/4 above its freely hanging level, as shown. If the bob is now released fro rest, the speed of the bob when it is at its lowest point is given by gl v. 8 v gl. 8 v gl. v gl. gl v. L L/4 5. A constant horizontal force of 6 N acts for 4 s on a 1 kg block, which is oving on a frictionless horizontal surface. What is this block s change in oentu during this 4 s tie interval? zero kg/s 4 kg/s 48 kg/s 88 kg/s 6. You hold a slingshot at ar s length, pull the light elastic band back to your chin, and release it to launch a pebble horizontally with a speed V. With the sae procedure, you fire a with a speed of 3V. What is the ratio of the ass of the pebble, pebble, to the ass of the,? pebble 9 pebble 3 pebble 1 pebble 1 3 pebble 1 9 Page 7 of 8

8 Saskatchewan High School Physics Scholarship Copetition May 10, 017; Page 8 7. A ping-pong ball oving to the East collides with a stationary bowling ball. The ping-pong ball bounces back to the West and the bowling ball oves very slowly in the East. Which object experienced the greater agnitude force during the collision? Neither, both experienced the sae agnitude force. The bowling ball. The ping-pong ball. The answer depends on the initial speed of the ping-pong ball. 8. A car, with ass, oving on a horizontal road with speed V, collides head on with a stationary pick-up truck which has a ass. After the collision the two vehicles are stuck together and ove as one. You ay ignore friction with the ground. What is the total kinetic energy of the car and truck just after the collision? 1 V 1 3 V 1 4 V 1 6 V 3 V 8 V 9. The radius of the Earth is R E. On the surface of the Earth the acceleration due to gravity is g. At a height above the Earth s surface of h the gravitational field strength is RE g g R h E R E RE h g RE R h E g R E RE h g 30. Three equal charges are placed at three corners of a square as shown. If we ignore the charge Q 3 the force on charge Q 1 has agnitude F. The agnitude of the net force on the charge Q is Q 1 Q F F zero 3F ( 1 )F Q The figure shows a side view of two charged horizontal conducting plates. The upper plate has a negative charge and the lower plate has a positive charge. A sall charged pellet, with ass is suspended between the two plates. Which one of the following stateents is FALSE? The electric field between the plates points up. The pellet ust have a negative charge. The agnitude of the electrostatic force on the pellet is equal to g The electric field lines between the plates are approxiately straight lines. END OF EXAMINATION Page 8 of 8