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10fall mt2

# 10fall mt2 - PH YSJZO Midterm-23 Name Studen t Tutorial...

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Unformatted text preview: PH YSJZO Midterm-23 Name: Studen t#: Tutorial Group: SF U email: - PHYSICS 120-Fa112010 Midterm Exam #ZB - Do not write in the table below — Write COMPLETE solutions: marks are given for intermediate calculations You can use g = 9.81 rn/s2 for the free fall acceleration. Ignore friction unless noted otherwise. l. (6p0ints) An old naval ship can fire 12 kg cannon balls from a 250 kg cannon with a speed of 100 m/s as shown in the picture. It is important to stop the recoil of the cannon. To do so, a large spring with spring constant 5.0x 104 N / m is attached to the front of the cannon. The other end of the spring is connected to the ship's frame. The spring is initially unstretched. (a) If the canon ﬁres, how much will the spring stretch from the recoil? (Ignoring friction). What energy transfer takes place? (b) If the spring is removed and the cannon is ﬁred again, how far would the cannon slide on a rough surface (with kinetic friction coefﬁcient uk=0.5) before coming to a stop? What energy transfer takes place in this case? (c) What can you say about momentum conservation when the cannon ﬁres at an angle of 100 instead of along the horizontal? 0) Romemluw {s canswcol omlt'l W oil/e.) MAL “exp/own” (4/1”? cm W, __ m . a MUct Mg » girl/Vt)ka 0 D If; a - Fug; —;. 433 m 0 K:‘> U5 Kit/who ageyaio f5 )gAY/O [WAC f 9 +054 ‘4: k; +JJ§J W I ,2 ‘2}: éém‘f 2” 2L {a / when, US: (If b) :5 Ella lu NM: (03:: law): wow will 5:» in ilqmai a” c (ﬂ (9 0w Mall-AS ii Z a. 5 2A 33} viz/E; L M Ur, ~~> « 2/”? U; “ i" / ’A‘ l C) Hat/Hemlth ML {En/l \$33ch is 8/77/ (mm Olly/3 Mi 0le ﬁrplokgiw" ,“We mart/Mail @101 PWWlS ML (a/nuou R’sz U0 Cor/lg. So‘mamenlw oiling Sgt/cm 05:3 z’é’i vane/l is wot mWé’Kleml PH Y5120 Midterm-28 Name: Student#: Tutorial Group: SF U email: 2. (6 points) A roller coaster car on a frictionless track (as shown on the “l right) starts from rest at height h. The track’s valley and hill consist of circular-shaped segments of radius R=14.0 m. 0 (a) Draw a free body diagram of the roller coaster car at the bottom of the valley and on top of the hill. (b) Find the maximum speed of the car so that it does not ﬂy off the track when going over the hill. (0) What is the maximum height hmax from which the roller coaster should start not to exceed the maximum speed derived in (b)? (d) What is the apparent weight of a passenger (of mass 70 kg) in the roller coaster car at the bottom of the valley after leaving from hmax? Q w% mm V\ Q”) Fg) b) Dwé viz foovvb‘wis Z —~ V139.” _._ M 1; W2 “m7 if”? at A \f '9 Y % hW2N+KC%K:Um \$0 OX 7 '7 ) % TK‘E :— U; T I [Oleﬁn gem Mags 0} Dale? laoiilsnrd U15 "1 Végl/lwwx U6 2: “if; 2 . 2. ”‘ R > nzmg+ﬂégnggw [43) 5 I § (LO 1! F c; H PHY5120 Midterm-23 Name: Student#: Tutorial Group: SFU email: 3. (6 points) Conceptual Questions I. You are standing on a skateboard, initially at rest. A friend throws a very heavy ball towards you. You can either catch the ball or deﬂect the ball back towards your friend (such that it moves away from you with the same speed as it was originally thrown). What should you do in order to minimize your speed on the skateboard? atch the ball (b) Deﬂect the ball (0) It does not matter (d) Not enough information mwxwwquxmmmm , mrmmmmmmimrmmwaimmwwymmm . II. A string is attached to the rear-view mirror of a car. A ball is hanging on the other end of the string. The car is driving around in a circle, at a constant speed. Which of the following lists gives all of the forces directly acting on the ball? a Tension, gravity, and the centripetal force @ ension and gravity (0) Tension, gravity, the centripetal force, and friction (d) Tension III. Two balls of equal mass move in vertical circles. Is the tension in string A greater than, less than or equal to the tension in string B if the balls travel with: (a) Equal speed: TA > T3 (Fill in either <,= or >) 7' (b) Equal angular velocity: TA g TB (Fill in either <,= or >) ~~~~~~ IV. What energy transformations can occur as a box slides down a sticky ramp. (a) U->K I [P9Em @ A ll of the above V. The figure to the right shows the potential energy (in Joule) as a function of displacement from equilibrium (in cm) for a horizontal mass on a spring. After the mass is displaced 7.5 cm from equilibrium it starts moving back and forth. (a) At a displacement of +5 cm indicate (in the graph) the contributions of potential and kinetic energy to the total mechanical energy. (b) Circle the point (or points) of stable equilibrium. GOOD LUCK” ...
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