Real-Life Examples of Linear Momentum

📚 Quick Study Guide

• 🚗 Definition: Linear momentum ($p$) is the product of an object's mass ($m$) and its velocity ($v$). Mathematically, $p = mv$.
• ⚖️ Conservation of Momentum: In a closed system, the total momentum remains constant if no external forces act on it. This means $p_{initial} = p_{final}$.
• 🚀 Impulse: Impulse ($J$) is the change in momentum of an object. $J = \Delta p = F\Delta t$, where $F$ is the force and $\Delta t$ is the time interval.
• 💥 Collisions:
  • Elastic collisions: Kinetic energy is conserved.
  • Inelastic collisions: Kinetic energy is not conserved (e.g., heat is generated).
• 🎯 Real-World Applications: Think about car crashes, billiard balls colliding, or even the recoil of a gun.

🧪 Practice Quiz

1. A 2 kg bowling ball is traveling at 5 m/s. What is its momentum?
   1. 5 kg m/s
   2. 7 kg m/s
   3. 10 kg m/s
   4. 2.5 kg m/s
2. A car of mass 1000 kg is moving at 20 m/s. It collides with a stationary truck of mass 2000 kg. If they stick together after the collision, what is their combined velocity?
   1. 5 m/s
   2. 6.67 m/s
   3. 10 m/s
   4. 13.33 m/s
3. A rocket expels gas at a high velocity. Which principle explains why the rocket moves forward?
   1. Newton's First Law
   2. Conservation of Energy
   3. Conservation of Momentum
   4. Newton's Law of Gravitation
4. A baseball of mass 0.15 kg is thrown at 40 m/s and is hit back at 50 m/s. What is the magnitude of the impulse on the ball?
   1. 1.5 Ns
   2. 13.5 Ns
   3. 6 Ns
   4. 7.5 Ns
5. Two ice skaters, one with mass 60 kg and the other 80 kg, stand facing each other. If the 60 kg skater pushes the other and moves back at 2 m/s, what is the velocity of the 80 kg skater?
   1. 1.5 m/s
   2. 2 m/s
   3. -1.5 m/s
   4. -2 m/s
6. A bullet of mass 0.01 kg is fired from a rifle of mass 5 kg. If the bullet leaves the rifle with a velocity of 300 m/s, what is the recoil velocity of the rifle?
   1. 0.6 m/s
   2. -0.6 m/s
   3. 1.5 m/s
   4. -1.5 m/s
7. A soccer ball is kicked with a force of 50 N for 0.1 seconds. What is the impulse imparted to the ball?
   1. 5 Ns
   2. 0.5 Ns
   3. 500 Ns
   4. 0.002 Ns