Fabulous Momentum Questions
1. A 20.0 kg child throws a 5.0 kg package horizontally from a boat
(80.0 kg) with a speed of 10.0 m/s. Calculate the resulting velocity of
the boat if it was initially at rest.
2. Calculate the force exerted on a rocket given that the
propelling gases that are expelled have a mass of 2000
kg with a speed of 60000 m/s over 2 seconds.
3. A 150 kg astronaut acquires a speed of2.5 m/s by pushing off with his
legs from a 2 200 kg space capsule.
a. What is the change in speed of the space capsule?
b. What is the average force exerted by the astronaut if the push lasts 0.20 s.
4. A 1.0 x l03 kg car moving east at 80.0 km/h overtakes a 1500 kg car moving east
at 40.0 km/h and collides with it. The two cars stick together. What is the initial
speed of the wreckage?
5. A 1200 kg car traveling east at 30.0 km/h collides with a 1 800 kg car, traveling
north at 20.0 km/h. What is the initial velocity of the wreckage?
6. A hunter has a rifle that can fire 60.0 g bullets with a speed of
900 m/s. A 40 kg leopard springs at him at 10.0 m/s. How many
bullets must the hunter fire into the leopard in order to stop him
in his tracks?
7. A 0.500 kg stone moving north at 4.0 m/s collides with a 4.00 kg lump of clay
moving west at 1.00 m/s. What is the velocity of the embedded stone after the
collision?
8. A 1.67 X 10-27 kg neutron traveling at 1.0 x l05 m/s collides head on with a
stationary 3.34 x10 -27 kg deuteron. After the collision, the deuteron moves off at
6.67 x l04 m/s. Determine the velocity of the neutron after collision.
9. Two automobiles are in an accident. Car A with mass of 2.00 x l03 kg was
traveling at 30.0 m/s north. Car B with mass of 2.50 x l03 kg was traveling at 20.0
m/s east. Find the velocity of the wreckage after the completely inelastic
collision.
10. Bullets whose masses are 20.0 g strike a wall at the rate of 10.0/s. They embed in
the wall and do not bounce. If the velocity of the bullets is 3.0x102 m/s, what is the
average force on the wall?
11. A bullet of 50.0 g is fired into a 1.00 kg wooden block
suspended on a string. If the velocity of the block is 5.0
m/s after impact and the bullet imbeds itself into the
block, find the velocity of the bullet before impact.
12. A 5.0 x l02 g ball rolling at 40 m/s collides with a stationary 2.0 kg ball. After the
collision, the 2.0 kg ball rolls at 16 m/s. Find the velocity of the 5.0 x l02 g ball
after the collision.
13. A 40.0 kg missile launched vertically is rising at 173 m/s
when it explodes into two fragments. A 32.0 kg fragment
is projected upwards at an angle of 30.0° to the vertical
with a velocity of 250 m/s. Find the velocity of the second
fragment immediately after the explosion.
14. A 5.0 kg mass moving at 3.0 m/s due north strikes a
stationary object of mass 2.0 kg and bounces off with a
velocity of 2.0 m/s 30.0° N of W. Determine the velocity of
the second object after the interaction.
15. (BONUS) An explosion blows a rock into 3 pieces. Two pieces go off at right
angles to each other, a 1.0 kg piece at 12 m/s and a 2.0 kg piece at 8.0 m/s. The
third piece flies off at 40.0 m/ s. Draw a vector diagram to show the direction in
which the third piece goes. What is its mass?
16. (BONUS) A 2.0 x l02 kg explosive device has a velocity of 50.0 m/s due east. On
explosion a 50.0 kg piece is emitted at 1.0 x l02 m/s, 40.0° S of E, another 30.0 kg
piece is emitted at 80.0 m/s, 50.0° W of N, and another 40.0 kg piece is emitted at
60.0 m/s, 30.0° N of E. Find the velocity of the fourth piece.
Answers
1. –0.5 m/s
2. 6 x 107 N
3. –0.17 m/s
b) 1875 N
4. 56 km/hr
5. 17 km/hr @ 45 N of E
6. 8 bullets
7. 0.99 m/s at 63 W of N
8. 3.34 x 104 m/s
9. 17.3 m/s @ 40 E of N
10. 60 N
11. 105 m/s
12. –24 m/s
13. 500 m/s sideways
14. 6.5 m/s N 30 E
15. 0.50 g
16. 75 m/s 5 N of E
for solutions see http://cabennet.mvsd.ca/PHYS40S/Momentum/Fabulous_Solns.pdf