* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Physics 144 (section 1) Homework 4
Velocity-addition formula wikipedia , lookup
Derivations of the Lorentz transformations wikipedia , lookup
Equations of motion wikipedia , lookup
Jerk (physics) wikipedia , lookup
Atomic theory wikipedia , lookup
Modified Newtonian dynamics wikipedia , lookup
Faster-than-light wikipedia , lookup
Newton's laws of motion wikipedia , lookup
Variable speed of light wikipedia , lookup
Rigid body dynamics wikipedia , lookup
Work (physics) wikipedia , lookup
N-body problem wikipedia , lookup
Mass in special relativity wikipedia , lookup
Hunting oscillation wikipedia , lookup
Classical central-force problem wikipedia , lookup
Specific impulse wikipedia , lookup
Seismometer wikipedia , lookup
Centripetal force wikipedia , lookup
Electromagnetic mass wikipedia , lookup
Mass versus weight wikipedia , lookup
Relativistic angular momentum wikipedia , lookup
€ Physics 144 (section 1) Homework 4 Due date: Friday, Nov 13, 2009, 12:00 AM (noon) Place: 3rd floor, CEB Drop Box labeled Phys 144 (1), near elevator Note: you may skip units during the middle of the computations, but the end result must have it or you will get a deduction. Write down what you understand even if you can’t fully solve the problem to get partial credits. Late submission (after first pickup by TA) will result in an automatic 15% markdown. Furthermore, any submission beyond noon, Monday will not be picked up or graded.. Problem 1 (20 pt) A 0.14‐kg baseball moves toward home plate with a velocity v i = (−36 m/s)xˆ . After striking the bat, the ball moves vertically upward with a velocity v f = (18 m/s)yˆ . (a) Find the direction and magnitude of the impulse delivered to the ball by the bat. Assume the ball and bat are in contact for 1.5 ms. (b) How would your answer to part (a) change if the mass of the ball were € doubled? (c) How would your answer to part (a) change if the mass of the bat were doubled instead? Problem 2 (15 pt) An object initially at rest breaks into two pieces as the result of an explosion. One piece has twice the kinetic energy of the other piece. What is the ratio of the masses of the two pieces? Which piece has more mass? Problem 3 (15 pt) A 0.44 kg block of wood hangs from the ceiling by a string, and a 0.072‐kg wad of putty is thrown straight upward, striking the bottom of the block with a speed of 5.74 m/s. The wad of putty sticks to the block. (a) Is the mechanical energy of the system conserved? (b) How high does the putty‐block system rise above the original position of the block? Problem 4 (14 pt) A 0.1 kg stone rests on a friction‐less, horizontal surface. A bullet of mass 6.00 g, traveling horizontally at 350 m/s, strikes the stone and rebounds horizontally at right angles to its original direction with a speed of 250 m/s. (a) Compute the magnitude and direction of the velocity of the stone after it is struck (b) Is the collision perfectly elastic and why? Problem 5 (20 pt) A 1200‐kg station wagon is moving along a straight highway at 12 m/s. Another car, with mass 1800 kg and speed of 20 m/s, has its center of mass 40.0 m ahead of the center of mass of the station wagon. (a) Find the position of the center of mass of the system consisting of the two automobiles. (b) Find the magnitude of the total momentum of the system from the given data. (c) Find the speed of he center of mass of the system. (d) Find the total momentum of the system using the speed of the center of mass. Compare to your results in part (b) and comment. Problem 6 (16 pt) A turntable with a diameter of 0.75 m is rotating about a fix axis with an initial angular velocity of 0.25 rev/s and a constant angular acceleration of 0.9 rev/s2 . (a) Compute the angular of the turntable after 0.2 s (b) Through how many revolutions has the turntable spun in this time interval? (c) What is the tangential speed of a point on the rim of the turntable at t=0.2 sec? (d) What is the magnitude of the resultant acceleration of a point on the rim at t=0.20 s?