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exam1_2col_ans - ISP209 Fall 2011 Exam #1 ...

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Unformatted text preview: ISP209 Fall 2011 Exam #1 Name:___________________________________________ Student #:______________________________________ Please write down your name and student # on both the exam and the scoring sheet. After you are finished with the exam, please place the scoring sheet inside the exam and turn in at the front of the lecture room. No form number is necessary. No section # is necessary. Do not begin working on the exam before permission is given. Keep your eyes on your own exam and no conversations. You will be given one verbal warning. The second violation will result in the exam being taken away and a grade of 0 assigned. No cell phones visible. Some useful constants: g=9.8 m/s2 G=6.67X10- 11 Nm2/kg2 MEarth=6X1024 kg REarth=6.37X106 m MSun=1.99X1030 kg RSun=6.98X108 m Distance from Earth to Sun=1.50X1011 m 1) Which of the expressions below is not a way to express 0.0303 in scientific notation? a) 3.03E- 02 b) 30.3E- 03 c) 0.00303E1 d) 0.303E- 01 e) 303.0E- 3 Match the SI unit with the corresponding quantity. (In the next 5 problems, each unit is used once. Fill in the correct bubble for the unit corresponding to mass for question 2, for force for question 3, etc.) a meter b m/s2 c Newton d second e kilogram 9) What was the major problem Galileo had to solve in his experiments on meauring the motion of falling objects? a) the studies were prohibited by the church b) the motion was occuring too quickly to be accurately measured c) the mathematics that he had available weren’t sophisticated enough for the needed calculations d) he wasn’t able to measure the lengths accurately enough 10 ) Which viewpoint did Emilie du Chatelet have that most other scientists of her day disagreed with? a) that the kinetic energy of an object was proportional to the square of the object’s speed b) that the momentum of an object depended linearly on the velocity c) that the potential energy of a system always equalled the kinetic energy d) that Newton’s 3 laws of motion were correct e) that admit they are given a fair chance to present their results 2) mass e 3) force c 4) acceleration b 5) distance a 6) time d 7 ) Which of the following is a characteristic of pseudoscience? a) the hypothesis is not at risk. If data does not agree with the hypothesis, then the data is assumed to be wrong b) proponents do not exploit the controversies and inadequacies in a competing theory c) all facts are considered and discussed d) proponents publish in scientific journals e) proponents admit they are given a fair chance to present their results 8) Which of the following quantities is not a vector quantity? a) b) c) d) e) Force Momentm Position Acceleration Mass 11) Through his precise experiments, Antoine de Lavoisier demonstrated that a) momentum is conserved b) that the momentum of an object depended linearly on the velocity c) the potential energy of a system always equalled the kinetic energy d) mass is conserved in chemical reactions e) E=mc2 12) Why does an astronaut in orbit feel weightless? a) he is constantly in free fall, missing the Earth b) there is no gravity in space c) the gravity from the Earth and the Moon cancel in space d) his acceleration is constant e) his velocity is constant 13) A car of mass 1180 kg slows down as the brakes are applied, as shown in the figure below. What (magnitude of) acceleration is the car experiencing? a= Δv 9 m / s − 0 m / s = = 3m / s 2 Δt 3s 17) What is the net force acting on the runner in question 16)? a) b) c) d) e) 9 N 240 N 2.3N 80 N N 0 N F=ma=(80kg)(3N/kg)=240N a) b) c) d) e) a= 18) How far does the runner go in the 3 seconds? 0 m/s2 0.67 m/s2 20 m/s2 15m/s2 2.3 m/s2 a) b) c) d) e) Δv 20 m / s − 0 m / s = = 0.67m / s 2 Δt 30 s 14) What magnitude of force is the car experiencing? a) b) c) d) e) 1450 N 20 N 1761 N 2180 N 791 N 1 1 x = at 2 = (3m / s 2 )(3s )2 = 13.5m 2 2 19) As it orbits around the Earth, the Hubble Space Telescope (mass of 11,110 kg) travels at a speed of 7900 m/s and is 560 km above the Earth’s surface. What is its kinetic energy? a) b) c) d) e) F=ma=(1180 kg)(0.67N/kg)=791N 15) Which of the scientists below described the motion of the planets with 3 laws? a) b) c) d) e) Johannes Kepler Galileo Galilei Emilie du Chatelet Aristotle Democritus 16) A runner with a mass of 80 kg accelerates from 0 m/s to 9 m/s in a time of 3 s. What is his acceleration? a) b) c) d) e) 27 m/s2 9 m/s2 3 m/s2 240 m/s2 17 m/s2 4.5 m 27 m 15 m 240 m 13.5 m 8.78E7 J 1.57E6 J 9.42E12 J 3.47E11 J 6.67E9 J KE=1/2mv2=1/2(11,110kg)(7900m/s)2=3.47E1 1 J 20) Two people are standing on ice skates facing each other. Person A, with a mass of 90 kg, pushes on person B, who has a mass of 60 kg, with a force of 60 N. What is the acceleration of person A? (Assume the ice is frictionless.) a) b) c) d) e) 23) A 2.0 kg ball is fired horizontially toward a hill with a speed of 20.0 m/s as shown in the picture. Assuming that friction is small, what is the maximum height, h, the ball will reach above the floor? 60 m/s2 90 m/s2 2.5 m/s2 1 m/s2 0.67 m/s2 a=F/m=60N/90kg=0.67 m/s2 ; the force on person A is equal and opposite to that on person B 21) Where, in the graph below is the speed the highest? b) 14.0 m a) b) c) d) A B C D a) 10.0 m c) 20.4 m d) 7.1 m e) 32 m 12 mv = mgh 2 v2 ( 20 m / 2 ) 2 h= = = 20.4 m 2 g 2(9.8m / s 2 ) 24) You throw a ball straight up. Air resistance is negligible. After the ball leaves your hand, which of the following statements is true? 22) Where, in the graph above, is the magnitude of the acceleration the largest? a) b) c) d) A B C D a) the ball experiences an upward force at first, which gradually diminishes as gravity takes over b) the ball experiences only the downward force of its own weight c) the ball experiences no forces in its motion d) the ball experiences an upward force as it rises and then a downward force as it falls e) the ball experiences the upward force of the throw and the downward force of its weight while it rises ,but only the downward force of the throw as it falls 1 y = gt 2 2 2y 2 ( 5m ) t2 = = = 1.02 s 2 g 9.8m / s 2 t = 1.01s 27. With what speed did he intially throw it? a) b) a) J c) 13.07 m/s v=20m/1.01s=19.8m/s Match the term below with its definition (each term will be used once): 28. Mass c 29. Speed b 30. Momentum d 31. Acceleration e 32. Velocity a D e) 3.69 m/s e) A d) 10 m/s d) H b) 16.5 m/s c) 25) A student is rowing a boat across a river, with the river current directed from the bottom of the page towards the top of the page. Which vector describes the motion that allows the sudent to end up on other side of the river directly across from where he started? The vectors represent the possible velocities of the student with respect to the river. 19.8 m/s K a) the speed and direction of an object b) magnitude of the rate of change of position 26. A student throws a ball horizontally from the top of a 5 m tower. It lands 20 m away. How long did it take to reach the ground? a) 0.52 s b) 2 s c) 1.53 s d) 5.42 s e) 1.01 s c) property of an object which determines the amount of acceleration for an applied force d) force is the rate of change of this quantity e) rate of change of velocity 33) A rifle fires a bullet. Given the relative masses of the rifle and the bullet, and the speed of the bullet, what is the speed of the rifle after the bullet leaves the rifle? a) b) c) d) e) 0 m/s 1.67 m/s 23.5 m/s 0.01 m/s 500 m/s prifle=pbullet (mrifle)(vrifle)=(mbullet)(vbullet) vrifle=(0.01kg)(500m/s)/3.0kg=1.67m/s e) none of these answers is correct 34) An elevator is able to raise 100 kg to a height of 40 m in 15 s. How much work does the elevator do? a) b) c) d) e) 2613 J 39,200 J 20,400 J 10,500 J 30,000 J W=Fd=ΔPE=mgh=(100kg)(9.8N/kg)(40m)= 39200J 35) What is the increase in potential energy of the 100 kg mass in the problem above? a) b) c) d) e) 2613 J 39,200 J 20,400 J 10,500 J 30,000 J 36) What is power output of the elevator in problem 34? a) b) c) d) e) 2613 W 39,200 W 20,400 W 10,500 W 30,000 W P=W/Δt=39,200J/15s=2613W 37) If an object has a constant speed and direction, what can we say about it? a) b) c) d) its acceleration is non- zero its velocity is constant the position of the object is constant the net force on the object is nonzero 38) Suppose truck A has a mass of 1000 kg and truck B has a mass of 2000 kg. Truck A is travelling at a speed of 50 m/s while truck B is travelling in the same direction at a speed of 30 m/s. The two stick together after the collision. How fast are they moving? a) 50 m/s b) 30 m/s c) 15.4 m/s d) 17.8 m/s e) 36.7 m/s Pi = Pf mA vA + mB vB = (mA + mB )v final v final = mA vA + mB vB (1500 kg)(50 m / s ) + (2000 kg)(30 m / s ) = m A + mB 3500 kg v final = 38.6 m / s 39) What would happen to your weight if the radius of the Earth were increased by a factor of 3,but its mass remained the same? a) b) c) d) e) it would remain the same it would increase by a factor of 3 it would decrease by a factor of 3 it would decrease by a factor of 9 it would increase by a factor of 9 40) What is the gravitation force between the Sun and the Earth? a) b) c) d) e) 2.22X1021 N 6.63X1019 N 3.54X1022 N 4.75X1025 N 1.98X1020 N F =G mEarth mSun (6 X10 24 kg)(1.99 X10 30 kg) = 6.67 X10 −11 Nm 2 / kG 2 r2 (1.5 X1011 m )2 F = 3.54 X10 22 N ...
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