Quiz1-10am-solutions

Quiz1-10am-solutions - Physics 1A Quiz#1 10 am class Before starting to answer questions bubble in your student ID and test version number(A,B,C or

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Unformatted text preview: Physics 1A, Quiz #1, 10 am class Before starting to answer questions bubble in your student ID# and test version number (A,B,C, or D on the bottom of this quiz page on your scantron form. If you do not bubble in this info your quiz will not be graded. For numeric answers two significant digits is enough. More digits is also ok. A small range of answers near the correct answer will be accepted. Use scientific notation (with "E" to indicate a power of ten) when needed. Note, however, that 3.1E-2 and 0.031 will be accepted as the same answer. Mark a minus sign when needed to indicate a negative value. Name___________________________________ Turn in this test form with your scantron form and also have your ID card out and ready to be checked. Using notes or books, or calculators which store notes or formulas is not allowed. Talking or looking at other students' tests is not allowed. 1) Which of the following statements is NOT true? A) A caliper can measure smaller lengths than an ordinary ruler B) A nanogram is 1E-9 grams. C) A stage micrometer can be used to calibrate the magnification of a microscope D) A meter used to be defined as the length between two marks on a Platinum bar kept in Paris. E) All of the above statements are true 2) Which of the following statements are true? A) If you use a caliper to measure the diameter of a needle a hundred times and find 0.87 mm every time this means the accuracy is at least 0.01 mm B) If a scale comes with an instruction manual stating that the precision is 1 gram, and this statement is true, and you measure a bone to weigh 100 grams, that means the true weight of the bone is somewhere between 99 and 101 grams. C) If you have measured a quantity multiple times, the best estimate for the true value is given by the standard deviation D) You are able to measure closer to the true value if you have a precision of 0.2 mm and accuracy of 0.1 mm than if you have a precision of 0.01 mm and accuracy of 0.4 mm. E) All of the above statements are false 3) Suppose the position of an object is given by x= 2t. What is the velocity at t=4? 4) What is your approximate height in meters? 5) Which of the following is NOT true about fundamental forces A) Gravity is the weakest B) Chemical reactions involve primarily electromagnetic forces C) The Strong force is responsible for holding the nuclei of atoms together D) The Weak force is responsible for radioactivity E) All of the above statements are true 3) 4) 5) 2) 1) A-1 6) A ball is thrown vertically up in the air with an initial velocity of 1 m/s. If the upward direction is taken to be positive, how does the vertical acceleration, a, of the ball vary during its flight after it leaves the person's hand? Assume that air friction is minimal. A) On the way up a<0, on the way down a<0 B) On the way up a>0, on the way down a>0 C) On the way up a>0, on the way down a<0 D) One the way up a=0, on the way down a<0. E) On the way up a<0, on the way down a>0 7) Suppose the force applied to an object is given by F=sin(2pt)+Ct2 . C=constant and t=time. What is the equation of motion for the object? Call x=position, v=velocity, a=acceleration, and m=mass. dv A) m =sin(2 pt) dt B) m C) m d2 v =sin(2 pt)+Ct2 dt2 d2 x =Ct2 dt2 6) 7) D) ma-Ct2 =sin(2 pt) E) None of the above 8) Suppose you have a small spherical bead moving slowly through water at room temperature in the forward direction (+x direction). The radius of the ball is 1 mm, the velocity is 1 mm/s, the mass is 0.1 g. What is the acceleration of the bead in m/s2 if fluid drag force is the only force acting on it? (Note: a is positive if pointing in the +x direction, negative if pointing in the -x direction). 9) Suppose muscle tissue is modeled as a spring with a spring constant of 10,000 N/m and the muscle is pulling an object of mass 20 kg. What is the acceleration of the object in m/s2 if the muscle is stretched by 0.5 cm from its equilibrium position and the force exerted by the muscle is the only force acting on the object? (express the answer as a positive number) 9) 8) A-2 Answer Key Testname: QUIZ1-10AM 1) E ID: USER-1 ID: USER-4 ID: USER-7 2) D 3) 0.35 4) must be from 1 to 2.5 meters ID: USER-10 5) E ID: USER-13 ID: USER-16 ID: USER-19 ID: USER-23 6) A 7) D 8) -1.9E-4 9) 2.5 ID: USER-25 A-3 "  #      %4)%5 #(!/2%0 .& 2(% 0%!$%0 2. #.-&)0, 2(% &.30 12!2%,%-21 !0% 203% %4)%5 /!'% .& 2(% 0%!$%0 - /!02)#3+!0 2(!2 )& 7.3 0% 0%&%00)-' 2. ,%!130)-' 2(% 203% 4!+3% )2 ,%!-1 7.3 0% )-2%0%12%$ )- !##30!#7 !-$ 2(!2 2(% +.5%0 2()1 4!+3% 2(% "%22%0 !##30!#7       !  %')--)-' 5)2( 7.30 (%)'(2 )- &%%2 50)22%- !1 ! $%#),!+ 31% 2(% &.++.5)-' #.-4%01).-1 2. '%2 ,%2%01 &2  )- )-   #, #,  ,  %% /!'%1 !-$ .& 2(% 0%!$%0 &.0 ! $%1#0)/2).- .& %!#( &.0#% !-$ 2. #.-&)0, !++  12!2%,%-21 !0% 203%  )-#% !)0 &0)#2).- )1 ,)-),!+ 2(% .-+7 #.-20)"32)-' !##%+%0!2).- )1    (% 3/5!0$ $)0%#2).- )1 $%&)-%$ 2. "% /.1)2)4% 1. )1 -%'!2)4% 1)-#% '0!4)27 /.)-21 2.5!0$ 2(% #%-2%0 .& 2(% !02(    %!00!-'% 2. 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This note was uploaded on 04/04/2010 for the course PHYS 1A PHYS 1A taught by Professor Smith during the Fall '10 term at UCSD.

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