Train Collision-Classical Physics-Exam Solution, Exams of Classical Physics

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S012 EXAM \ SoLuTions (Oct 6, 2005) FALL 200s Problem 1 of 5 Short answer questions. (10 points) Note: DO NOT spend too much time on this problem! It is worth fewer points than the other 4 problems. For each question, circle the correct answer: (a) (2 points) A bee and a train collide. Compared to the magnitude of the force experienced by the bee, the magnitude of the force experienced by the train is smaller larger dependent on other details (From Newton's third lag) (b) (2 points) A point mass m is placed inside a thin spherical shell of mass M and radius R, at a distance R/2 from the center. Let * be a radial unit vector pointing from the point mass away from the center of the shell. The gravitational force exerted on the point mass by the spherical shell is 4GMm = GMrm 4 GMm « 4GMm 4 Se Sere +o t +t (c) (2 points) A mass M suspended from the ceiling by a spring (with spring constant k) undergoes simple harmonic motion with an oscillation period P. If the mass is doubled, then the new oscillation period is P/2 PIV? P () 2P 21 w{& » Ps oy (2 points) A block of mass M slides down a inclined plane with friction coefficient ps. The surface area of the block in contact with the inclined plane is A, and the frictional force on the block is f. If we use a different block (made of the same material) with contact area 2A but the same mass VW, then the frictional force on the second block will be approximately tA f/2 ® af 4g FapN depends on weight but not on surFace area (2 points) When a mass moves through air or fluid at low velocity, it experiences a viscous drag force. (This is different than the turbulent drag felt at high velocity.) For a low velocity v, the viscous drag force is approximately proportional to © vy ve ot ve (d s docsity.com