Honors Physics
Work Sheet #2
Conservation of Linear Momentum
1.  A 60-kg astronaut floating at rest in space outside a space capsule throws his 0.50-kg hammer such
that it moves with a speed of 10 m s relative to the capsule. What happens to the astronaut?
2.
 In a pairs figure-skating competition, a 65-kg man and his 45-kg female partner stand facing each
other on skates on the ice. If they push apart and the woman has a velocity of 1.5 m s eastward, what is
the velocity of her partner? (Neglect friction.)
3.  To get off a frozen, frictionless lake, a 65.0-kg person takes off a 0.150-kg shoe and throws it
horizontally, directly away from the shore with a speed of 2.00 m s. If the person is 5.00 m from the
shore, how long does he take to reach it?
4. IE  An object initially at rest explodes and splits into three fragments. The first fragment flies off to
the west, and the second fragment flies off to the south. The third fragment will fly off toward a general
direction of (1) southwest, (2) north of east, (3) either due north or due east. Why? (b) If the object has a
mass of 3.0 kg, the first fragment has a mass of 0.50 kg and a speed of 2.8m s, and the second fragment
has a mass of 1.3 kg and a speed of 1.5 m s , what are the speed and direction of the third fragment?
5.  Suppose that the 3.0-kg object in Exercise 58 is initially traveling at a speed of 2.5m s in the
positive x-direction. What will be the speed and direction of the third fragment in this case? 7.6 m s,
6.  Two balls of equal mass (0.50 kg) approach the origin along the positive x- and y-axes at the same
speed (3.3 m/s). (a) What is the total momentum of the system? (b) Will the balls necessarily collide at
the origin? What is the total momentum of the system after both balls have passed through the origin?
Answers
1. moves 0.083 m s in opposite direction
2. 1.0 m s westward
3. 1.08 103 s  18.1 min
4. (a) (2) north of east (b) 2.0 m s , 54° north of east
5. 12° above the  x -axis
6. (a) 2.3 kg  m s, 45 below the  x axis (b) no; same as in (a)