Page 334 - Dynamics of Mechanical Systems

0593_C09_fm Page 315 Monday, May 6, 2002 2:50 PM

Principles of Impulse and Momentum 315

M(Nm)
100

FIGURE P9.6.1 O 50
Moment applied to a rotor. t (msec)

Sections 9.7, 9.8, and 9.9 Conservation of Momentum Principles and Examples
P9.7.1: A 3220-lb automobile traveling at 35 mph strikes the rear of a stopped 2800-lb car.
Assuming that the vehicles move together after impact, find their common speed.
P9.7.2: A 3000-lb pickup truck traveling north at 55 mph collides head on with a 2500-lb
southbound automobile traveling at 65 mph. Assuming the vehicles move together after
impact, find their common speed and direction of movement.
P9.7.3: A 2900-lb eastbound automobile A collides at an intersection with a 3300-lb north-
bound automobile B, as shown in Figure P9.7.3. If after the collision the vehicles move
together at 25 mph 30 degrees northeast, what were their speeds just prior to impact?

N
25 mph
V Post-impact
A
30° Common Velocity
A E
2900 lb Point of Impact
V
B
B
FIGURE P9.7.3
Intersection collision. 3300 lb

P9.7.4: See Problem P9.7.3. Suppose the pre-impact speeds of automobiles A and B are 30
mph and 25 mph, respectively. Find the common post-impact speed and direction.
P9.7.5: A 3500-lb automobile A traveling at 30 mph strikes a stopped automobile B in the
right rear wheel, as shown in Figure P9.7.5. Let B weigh 2800 lb and let the mass center

B stopped

2800 lb

30 mph

FIGURE P9.7.5 A
Side impact to the rear of a stopped
vehicle. 3500 lb