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2011test2v1solution

# 2011test2v1solution - Concepts of Physics Class Test II V1...

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Unformatted text preview: Concepts of Physics: Class Test II V1 31 October 2011 Name: 50M Hon. Instructions 0 There are 9 questions on 5 pages. Total: a Show your reasoning and calculations and always justify your answers. Physical constants and useful formulae distance traveled s eed = p time elapsed h ' 1 - , acceleration = W}. tlme elapsed 1 distance = E x acceleration X time2 ﬁnal speed = initial speed + acceleration x time , net force acceleratlon = —— mass earth’s gravitational force 2 mass x 9.8 1 KB = 5 x mass x (speed)2 gravPE = mass x 9.8 x height energy gain time elapsed useful energy output energy input 1 time per cycle power = efﬁciency = frequency = wave speed a wavelength x frequency 01 s:— 1.“ WE -t 1 d=-xax§ 2 vf=w+axt F a:— m Fg’rm' earth = m X 9.8 KE=%mxﬁ PE=mx9.8><h pi t _Eoutput 5- Einput 1 1”? s=/\xf Phys 100 Fall 2011 K: [[2 MU‘L Question 1 g Zx‘l.K x6 = sz4.3. "8 Two balls are thrown upward above the ground. Ball A has mass 4kg and ball B has mass 2kg. A1: a given moment their positions are as illustrated and ball A A 6 m moves with speed 8 m/s while ball B moves with speed 10 m/s. 4 In a) Which of the following (choose one) is true? @ A has a larger kinetic energy than B. ii) A has a smaller kinetic energy than B. iii) A has the same kinetic energy as B. b) Which of the following (choose one) is true? 69 A has a larger potential energy than B. ii) A has a smaller potential energy than B. iii) A has the same- potential energy as B. Question 2 A ball, of mass 0.25 kg, is released from rest at the point on a track as indicated in the diagram. The ball slides down the frictionless track without any air B resistance. The is released at a point 20m above the ground (the horizontal line in the diagram). a) Determine the total energy of the ball. A 0 new»: LE: 0 The! 0 : “DE:- mm x M’x Malt} :— 0,zs,<4,t,e20 e b) What type (or types) of energy does the ball have at the hill point labeled B? PP: rs now-1cm bray USS team at Wm. So 1642!: M445? be am am KE as we“, c) How does the kinetic energy of the ball at point C compare to that at point A? SOME Since, E:- K€+PE and P555 zero) +5.0. K98 Wm be 1% 3W. Question 3 A car is initially at rest at the top of an incline and is released. It reaches the bottom of the incline and slides for some distance along the horizontal section until it stops. 1Which of the following (choose one) is true of the sum of kinetic and potential energies, K E + PE? 3.) K E + PE stays constant throughout the motion. blinking, ICE? 20 b K E + PE increases throughout the motion. PE- no}— 35 : E + PE decreases throughout the motion. _ . KEiPE 'mﬁ-um. Pm l c : ' . a IE 0 .30 1554sz—6 /4 Question 4 pg: 0 decreases A ﬂuorescent bulb is on for 10min and uses 600J of energy. An incandescent bulb is on for 2min and uses 300 J of energy. For which bulb is the power used the greatest? Explain your p=ermrgg me: P: (”005 —— IW HwL (Owed answer. [Mandamni ?OLU-€f : 30d __ 25W zxéﬁé lncmdQSCM‘l' 9mg Ea war / 6 Question 5 Three bulbs each take electric energy input and pro— duce light energy output. These are described in the table. Which of the following (choose one) describes the correct rank of the eﬂ'iciencies of the bulbs? a.) Green largest, red middle, blue smallest. b) Red largest, green middle, blue smallest , '-‘I --| ---| o. --| c) Green largest, blue middle, red smallest. ﬂight-6'18 1 Lia L-i E' : f Olue largest, green middle, red smallest. Question 6 A segment of a continuous wave on a string is illustrated below. The point on the string marked A moves up and down 20 times per second. wavel-UWGHM a) Determine the wavelength of the wave. 343 +64 diagram 20M 2. b) Determine the wavespeed. 'ZOJn'MSPeSLcmoK ﬂilfq= 20% 5 waveggm; wwelwsli heal: 20M~c20H%.—. 4.00M“ c) A wave of wavelength 5 m is produced on the same string. Determine how many times does the point marked A moves up and down in one second as this wave passes? W ‘F‘mumﬂ‘ 4o_o _/2’—_RE/ 5 400 = 5 x Fm?” Question 7 A pulse travels to the right along a string. A snapshot at one moment is as indicated. A head is stuck to a particular point on the string. ”Which of the following (choose one) describes how the bead moves as the pulse passes its location? a) First right then left. b) First left then right. c First down then up. a? irst up then down. Question 8 Two light waves are depicted in the diagram. Case A W wad —-—-- 9mllnr wawlyjét Jo [mayo atom. Case B a) Which of the following (choose one) is true? i) The frequency of A is larger than that of B. W @The frequency of A is smaller than that of B. M I iii) The frequency of A is the same as that of B. S k LU‘ “0.6% b) Which of the following (choose one) is true? -—_'D [algcr far largo mum @Ehe light corresponding to A more intense (brighter) than that for B. -—‘p “61A ii) The light corresponding to B more intense (brighter) than that for A. iii) The light corresponding to A has the same brightness as that for B. {6 Question 9 Two pulses each travel along a string toward each other with speed 2cm/s. The units on the axes are cm. Sketch the shape of the string at an instant 1 5 later. When the pulses overlap exactly, what is the peak height of the string? see diagram. \$91601} overlap hQ'gM-z +2 —1 3 +1, CZ) ...
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