Wright State University
Department of Mechanical and Materials Engineering
ME 213, Winter 2011
ME 213 DYNAMICS: MIDTERM EXAM 2
Open Book, Closed Notes, DO NOT write on this sheet,
Show all work for partial credit
Problem 1 (20 points): A package is projected 8 m up a 15° incline so that it just reaches
the top of the incline with zero velocity. Knowing that the coefficient of kinetic friction
between the package and the incline is 0.10, use the principle of work and energy to
determine the initial velocity of the package at point A.
8m
Problem 2 (45 points): One of the requirements for tennis balls to be used in official
competition is that, when dropped onto a rigid surface from a height of 84 in., the height
of the first bounce of the ball must be at least 48 in. Determine the coefficient of
restitution of the tennis balls satisfying this requirement by using the conservation of
energy equation.
Problem 3 (35 points): A bullet is fired with a horizontal velocity of 1500 ft/s through a
6-lb block A and becomes embedded in a 4.95-lb block B. Knowing that blocks A and B
start moving with velocities of 4 ft/s and 8 ft/s, respectively, determine (a) the weight of
the bullet and (b) the velocity of the bullet as it travels between the two blocks using the
principle of conservation of linear momentum.