Moment of Inertia of Rod - General Physics - Past Exam, Exams of Physics

Download Moment of Inertia of Rod - General Physics - Past Exam and more Exams Physics in PDF only on Docsity! Physics 220 — Exam #3 November 18 2003 This exam consists of 12 problems on 7 pages. Please check that you have them all. All of the formulas that you will need are given below. You may also use a calculator. sin? = y/r cos = a/r tané = y/x r y average speed = sistance traveled g = 9.8 m/s? A average velocity = @ se “leplacement x instantarieous velocity = slope of position versus time instantaneous acceleration = slope of velocity versus time For constant acceleration: B= xo + vot + 4at? vy = up + at uv? = uf + 2a(x — 20) F = ma mae , = psN (static friction) Friction = px N (sliding friction) Poravity = SE G = 6.67 x 107"! Nm?/kg? Gy, = v2/r KE = 3m’ W = Fd cos6 PE gravity = mgh power = work/At p= mi Ap = impulse = FAt KE = }1w? I=DmR* 7 = force x (lever arm) = Ia L=Iw Fapring = — ha PE spring = kx? x = Asin(wt) us Aw cos(wt) w= kfm w= Vo/h w= Inf f=1/T For constant angular acceleration: 8 = 0 + wot + fat? w = wo + at w? = uw + 2a(@ — 4%) KE=iu?/2 Lew r=la @=s8/f we=ufr asafr w/t Pressure = Force/area Ayu = Agus Py + pghy + put/2 = Pa + pgha + pu;/2 Archimedes principle: buoyant force = weight of fiuid displaced 1. A rod of length 2.5 m is hinged at one end. It starts from rest and swings to the bottom of its arc. Find the speed of the END of the rod when it reaches the bottom. The moment of inertia of a rod that pivots about one end.is J = ML?/3. (a) 8.6 m/s (b) 7.0 m/s (c) 4.5 m/s (d) 14 m/s (e) 11 m/s 2. A compact disk of mass 0.025 kg and radius 0.080 m is spinning freely with an angular velocity of 1000 radians/sec. A bug of mass 0.0075 kg. then lands on the outer edge of the CD, and this causes the CD to spin more slowly. Find the angular velocity after the moth lands on the CD. The moment of inertia of a disk is J = mR?/2. t bug \ t (a) 1000 radians/s <—__», —_—— (b) 1600 radians/s R I (c) 300 radians/s \ (d) 630 radians/s (e) 770 radians/s 7. A plank of length 7.5 m and mass 55 kg sits at rest on two supports as shown below. The mass of the plank is distributed uniformly. A child of mass 25 kg also sits on the plank a distance 2.0 m from the left end. Find the force of the right support on the plank. 2.0m <--> (a) 780 N (b) 420 N {c) 330 N (d) 34.N (e) 26N 8. Two masses (m, = 12 kg and m2 = 18 kg) are connected by a string that passes over a pulley. The pulley HAS MASS, with mputtey = 16 kg. There is no friction between m, and the table. If the system is released from rest, find the speed of mg after it has moved a distance of 1.5 m. (The moment of inertia of the pulley is I = (mpuneyR?)/2.) (a) 9.1 m/s (b) 13 m/s (c) 5.9 m/s (d) 3.7 m/s (e) 23 m/s 9. A block of wood (density 750 kg/m?) floats in oil with 80% of the block submerged. Find the density of the oil. i (a) 750 kg/m? (b) 600 kg/m* (c) 1200 kg/m? (d) 940 kg/m? (e) 1500 kg/m> 10. A mass connected to a spring undergoes simple harmonic motion ~ the figure shows the displacement of the mass as a function of time. At what point is the kinetic energy of the mass a maximum? x[A | | (a) A (b) B () Cc (4) D (e) E 11. 12. A pendulum is constructed by tying a brick of mass m = 30 kg to a massless rope of length 30 m. The other end of the rope is tied to the top of the bell tower. The brick is then pulled to one side (as shown in the figure) and released. How long will it take the brick to reach the bottom point on its trajectory? A spring with k = 35 N/m is suspended vertically. A block of mass 2.5 kg is attached to the unstretched spring and released from rest. The block then undergoes simple harmonic motion. What is the maximum amount / that the spring is stretched as the block oscillates up and down? The End