CIVE261 ENGINEERING MECHANICS DYNAMICS

							Water Resources, Hydrologic and Environmental Sciences Civil and Environmental Engineering Department Fort Collins, CO 80523-1372 (970) 491-7621

CIVE261 ENGINEERING MECHANICS: DYNAMICS
Spring 2009

SECOND MIDTERM EXAM
Tuesday, March 24, 2009 – 5:30 – 7:000 PM Room 120 Engineering – Hammond Auditorium You may not consult any books, notes, or inanimate references. You may not consult with another person. You may not copy another student’s solutions. PROBLEM 1 PROBLEM 3

During a high-speed chase, an 1100-kg sports car traveling at a speed of 160 km/h just loses contact with the road as it reaches the crest A of a hill. (a) Determine the radius of curvature ρ of the vertical profile of the road at A. (b) Using the value of ρ found in part a, determine the force exerted on a 70-kg driver by the seat of his 1400-kg car as the car, traveling at a constant speed of 80 km/h, passes through A.

A 2.5-lb block B is moving with a velocity v0 of magnitude vo = 6 ft/s as it hits the 1.5-lb sphere A, which is at rest and hanging from a cord attached at O. Knowing that µk = 0.6 between the block and the horizontal surface and e = 0.8 between the block and the sphere, determine after impact (a) the maximum height h reached by the sphere, (b) the distance x traveled by the block.

PROBLEM 2

PROBLEM 4

Rod OA rotates about O in a horizontal plane. The motion of the 400-g collar B is defined by the relations r = 500 + 300sinπt and θ = 2π (t2−2t), where r is expressed in millimeters, t in seconds, and θ in radians. Determine the radial and transverse components of the force exerted on the collar when (a) t = 0, (b) t = 0.8 s.

A 70-kg skier starts from rest at point A and skis down the slope shown. Neglecting friction, determine the force exerted on the skier by the snow (a) just before the skier reaches B, (b) immediately after he has passed through B. (c) Does the skier become airborne before reaching C? Neglect the height of the skier compared to the radii of curvature.

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Jorge A. Ramirez