FA7.2 - Conservation of Momentum
Get the assessment: FA07.2.docx
Get more Practice Problems: Worksheet-ConservationOfMomentum7.2.docx
The formative assessment solved:
1. A bullet going 481 m/s imbeds in a stationary block of wood. The bullet and block combo are going 5.27 m/s after the collision, and the combo has a mass of 12.1 kg (Bullet and block). What was the mass of the bullet?
(0.133 kg)
2. A 65.0 kg person dives 3.68 m/s to the right off of a 23.0 kg cart. What is the velocity of the cart if the cart and person were initially at rest?
(10.4 m/s to the left)
3. 68.0 kg-Francois running 7.80 m/s jumps on a 45.3 kg cart already rolling at 2.30 m/s in the same direction. What speed are they going after he jumps on?
(5.60 m/s)
4. Bumper car A (340 Kg) with going East collides with the rear of car B (550 Kg) which has a velocity of 2.4 m/s East. After the collision, car A has a velocity of 1.2 m/s to the West, and B has a velocity of 5.40 m/s to the East. What is the velocity of car A before the collision?
(3.65 m/s to the East)
Another Example:
Boots of Spanish Leather
5. 94.0 kg Thor is standing on a 41.0 kg cart, and is holding a 6.40 kg hammer. Everything is moving to the right at 1.30 m/s. After he throws the hammer, he is moving 3.70 m/s to the right. What speed and in what direction did he throw the hammer?
(49.3 m/s to the left)
Another example:
Another:
Help with the Quizlette:
1) A 6.10 g bullet going 830. m/s imbeds in a stationary 310. g block of wood. What is the velocity of the block of wood just after the collision? (16.0 m/s) <Video>
2) A 6.50 g bullet imbeds in a stationary 170. g block of wood. The bullet and block combo are going 21.0 m/s after the collision. What was the velocity of the bullet before the collision? (570. m/s) <Video>
3) A person at rest fires a 1.70 g rifle bullet to the right at 1320. m/s. The person recoils at 0.0290 m/s to the left after this. What must be the mass of the person? (77.4 kg) <Video>
4) A 52.0 kg person at rest fires a 1.80 g rifle bullet to the right. The person recoils at 0.0720 m/s to the left after this. What must be the velocity of the bullet? (2080 m/s) <Video>
5) A 61.0 kg person fires a 5.40 g rifle shell at 870. m/s. If the person is initially at rest on a frictionless surface, what is their recoil velocity after firing? (0.0770 m/s) <Video>
6) A 3500 kg car going 23.0 m/s strikes a 1400 kg car traveling in the same direction at 13.0 m/s from behind. The two cars stick together. What velocity are they going after the collision? (20.1 m/s) <Video>
7) A 3800 kg car (going an unknown velocity) strikes a 1100 kg car traveling in the same direction at 17.0 m/s from behind. The two cars stick together and have a velocity of 23.0 m/s. What velocity was the first car going before the collision? (24.7 m/s) <Video>
8) A 1200 kg car going 24.0 m/s strikes a 2600 kg car traveling in the same direction from behind. The two cars stick together and are going 19.0 m/s just after the collision. What velocity did the other car have before the collision? (16.7 m/s) <Video>
9) Two football players strike each other head on. Player 1 has a mass of 120. kg and is running 3.30 m/s to the East, and player 2 has a mass of 95.0 kg is running 6.20 m/s to the West. What is their post-collision velocity if they stick together? (Speed and direction) (0.898 m/s west) <Video>
10) Two football players strike each other head on. Player 1 has a mass of 110. kg and is running 3.50 m/s to the East, and player 2 has a mass of 85.0 kg is running to the West. If they stick together, and are together moving 1.90 m/s to the West after the collision, was the velocity of player 2 before the collision? (Speed and direction) (8.89 m/s west) <Video>
11) Bumper car A (340. Kg) with velocity 4.50 m/s East collides with the rear of car B (610. Kg) which has a velocity of 2.40 m/s East. After the collision, car A has a velocity of 1.40 m/s to the West. What is the velocity of car B after the collision? (Speed and direction) (5.69 m/s east) <Video>
12) Bumper car A (480. Kg) with velocity 3.90 m/s East collides with the front of car B (410. Kg) which has a velocity of 5.10 m/s West. After the collision, car B has a velocity of 1.50 m/s to the East. What is the velocity of car A after the collision? (Speed and direction) (1.74 m/s west) <Video>
13) 85.0 kg Thor is standing on a 35.0 kg cart, and is holding a 6.40 kg hammer. Everything is moving to the right at 3.40 m/s. What is the velocity of Thor and cart if he throws the hammer 25.0 m/s to the left? (Speed and direction) (4.91 m/s right) <Video>
14) 82.0 kg Thor is standing on a 25.0 kg cart, and is holding a 6.20 kg hammer. Everything is moving to the right at 2.40 m/s. What is the velocity of Thor and cart if he throws the hammer 18.0 m/s to the left? (3.58 m/s right) <Video>
15) 88.0 kg Thor is standing on a 42.0 kg cart, and is holding a 8.40 kg hammer. Everything is moving to the right at 4.30 m/s. After he throws the hammer, he and the cart are moving 6.60 m/s to the right. What speed and in what direction did he throw the hammer?(31.3 m/s left) <Video>
More Practice Problems:
Momentum Practice Questions for 7.2 (Links are video solutions - Bold are problems you should know how to do for the assessments)
1. A 1200 Kg car going 13 m/s collides with a 4200 Kg truck at rest. Their bumpers lock. What is their speed afterwards? (2.89 m/s) Practice 7 2 #1
2. A 60.0 Kg person running 3.00 m/s East collides head on with a 100. Kg person running 2.00 m/s the other way. What is their final velocity if they stick together? (0.125 m/s West) Practice 7 2 #2
3. A 50. Kg ice skater at rest throws a 5.0 Kg shot put at a velocity of +3.5 m/s. What is the recoil velocity of the skater? (-0.35 m/s) Practice 7 2 #3
4. A 1200 Kg car going 15 m/s rear-ends with a 800. Kg car going 5.0 m/s in the same direction. Their bumpers lock. What is their speed afterwards? (11 m/s) Practice 7 2 #4
5. A bullet going 375 m/s embeds in a stationary block of wood. The 1.42 kg bullet and block combo are going 16.5 m/s after the collision. What was the mass of the bullet? (0.0625 kg) Practice 7 2 #5
6. Two football players strike each other head on. Player 1 has a mass of 72.0 kg and is running 5.20 m/s to the East, and player 2 has a mass of 86.0 kg is running to the West. If they stick together, and are together moving 1.60 m/s to the West after the collision, was the velocity of player 2 before the collision? (Speed and direction) (7.29 m/s to the West) Practice 7.2 #6
7. Two football players strike each other head on. Player 1 has a mass of 119 kg and is running 6.20 m/s to the East, and player 2 has a mass of 102 kg is running 4.20 m/s to the West. What is their post-collision velocity if they stick together? (Speed and direction) (1.40 m/s East) Practice 7 2 #7
8. A 2000. Kg airplane going 45.0 m/s fires a 2.00 Kg shell forward at a speed of 1200. m/s. What is the final velocity of the plane? (Planes crashed because of this!) (43.8 m/s) Practice 7 2 #8
9. A 14.5 g bullet traveling 783 m/s horizontally strikes a 9.24 Kg block of wood at rest on a level frictionless table. The bullet goes through the block, but is traveling only 382 m/s in the same direction after the collision. What is the velocity of the block after the collision? (Assume the block loses no mass) (0.629 m/s) Practice 7 2 #9
10. Bumper car A (326 Kg) with velocity 3.7 m/s East collides with the rear of car B (536 Kg) which has a velocity of 2.4 m/s East. After the collision, car A has a velocity of 1.2 m/s to the West. What is the velocity of car B after the collision? (5.38 m/s East) Practice 7 2 #10
11. Bumper car A (428 Kg) with velocity 2.40 m/s East collides with the front of car B (509 Kg) which has a velocity of 3.10 m/s West. After the collision, car A has a velocity of 2.30 m/s to the West. What is the velocity of car B after the collision? (Speed and direction) (0.852 m/s to the East) Practice 7 2 #11
12. 95.0 kg Thor is standing on a 65.0 kg cart, and is holding a 8.90 kg hammer. Everything is moving to the right at 1.80 m/s. What is the velocity of Thor and cart if he throws the hammer 12.5 m/s to the right? (1.205 m/s) Practice 7 2 #12
13. 82.0 kg Big J Sandvik is standing on a 23.0 kg golf cart, and is holding a 3.60 kg golf club. Everything is moving to the right at 1.45 m/s. After he throws the golf club, he and his cart are moving 2.16 m/s to the right. What speed and in what direction did Big J Sandvik throw the golf club? (19.3 m/s to the left) Practice 7 2 #13
14. 96.0 kg Thor is standing on a 45 kg cart, and is holding a 9.40 kg hammer. Everything is moving to the right at 2.30 m/s. After he throws the hammer, he is moving 1.70 m/s to the right. What speed and in what direction did he throw the hammer? (11.3 m/s to the right) Practice 7.2 #14
15. 78.0 kg Big J Sandvik is standing on a 15.0 kg golf cart, and is holding a 3.40 kg golf club. Everything is moving to the right at some speed. After he throws the club, he is moving on the cart 3.00 m/s to the right and the golf club is moving to the right at 23.0 m/s. What speed and in what direction was he, his cart and his club going to begin with? (3.71 m/s to the right) Practice 7.2 #15
16. A 132.45 g bullet traveling at 386 m/s rips a hole through a 1.34 Kg block of wood at rest on some frictionless ice. The bullet is traveling 153 m/s following the collision, what is the speed of the block? (23.0 m/s) Practice 7 2 #16
17. A 153 gram bullet going 452 m/s goes through the first of two stationary 3.50 kg blocks of wood, and sticks in the second. After this, the first block is traveling at 6.50 m/s in the same direction. What speed are the second block and bullet going? (12.7 m/s) What is the bullet’s velocity between the blocks? (303 m/s) Practice 7 2 #17
18. 60.0 kg Brennen is playing on two flatbed rail cars initially at rest. Car A has a mass of 560. kg and B 780. kg. He reaches a velocity of +5.20 m/s on A, before jumping to B where he slows to +3.40 m/s before jumping off the other end. The cars are uncoupled, and rest on a frictionless track: Practice 7 2 #18
i. What is the velocity of car A when he is in midair? (-0.557 m/s)
ii. What is the velocity of car B when he leaves it? (+0.138 m/s)
iii. What would have been the velocity of car B had he remained there, and not jumped off? (+0.371 m/s)
iv. What would the velocity of car B have been had he jumped off the back of it to give himself a velocity of zero? (+0.40 m/s)
The Instruction for this unit:
You should look at many examples if you need to...
