Wright State University ME 499, Spring 1997

Wright State University
Department of Mechanical and Materials Engineering
Spring 2011
Open Book, Closed Notes, DO NOT Write on this Sheet
Show All Work for Partial Credit
Problem 1 (20 points): The 20-kg block A slides along the smooth slot. Spring B has a
spring constant of 1000 N/m, and spring C has a spring constant of 500 N/m. In the
position shown, spring B is stretched 0.8 m, spring C is unstressed, and the block has a
velocity of 10 m/s down the slot. Using the conservation of energy principle, determine
the velocity of block A when it reaches position D.
Problem 2 (20 points): The 4-oz baseball is thrown horizontally toward a batter at 60
ft/s. After being struck by the bat A, the velocity of the ball is 120 ft/s in the direction
shown. Determine the magnitude and direction of the average force applied to the ball by
the bat during the 0.02-s contact period.
Problem 3 (15 points): A 0.08-lb bullet is fired from a rifle that is clamped to a trolley.
The combined weight of the rifle and trolley is 20 lb. After firing, the velocity of the
trolley is known to be vA = 4.8 ft/s to the left. Calculate vB, the velocity of the bullet after
firing, and the muzzle velocity (the velocity of the bullet relative to the barrel of the rifle).
Problem 4 (45 points): A system consists of three particles that have the velocities
shown at a certain instant. Compute the following for the system: (a) the coordinates of
the mass center G; (b) the linear momentum; and (c) the angular momentum about the