Everyday examples of pushes and pulls changing speed.

📚 Quick Study Guide

• 🍎 Force: A push or pull that can change an object's motion.
• 🚗 Speed: The rate at which an object is moving.
• 📈 Acceleration: The rate at which speed changes.
• Newton's Second Law: The acceleration of an object is directly proportional to the net force acting on the object, is in the same direction as the net force, and is inversely proportional to the mass of the object. $F = ma$, where $F$ is force, $m$ is mass, and $a$ is acceleration.
• 🚲 A push *increases* speed in the direction of the push.
• 🛑 A pull *decreases* speed if it opposes the motion, or changes the direction of motion.

🧪 Practice Quiz

1. A person kicking a soccer ball is an example of:
   1. A pull increasing speed.
   2. A push increasing speed.
   3. A pull decreasing speed.
   4. A push decreasing speed.


2. A car applying its brakes is an example of:
   1. A pull increasing speed.
   2. A push increasing speed.
   3. A pull decreasing speed.
   4. A push decreasing speed.


3. A child swinging on a swing set being pushed from behind is an example of:
   1. A pull decreasing speed.
   2. A push increasing speed.
   3. A pull increasing speed.
   4. A push decreasing speed.


4. A parachute slowing down a sky diver is an example of:
   1. A pull increasing speed.
   2. A push increasing speed.
   3. A pull decreasing speed.
   4. A push decreasing speed.


5. A rocket launching into space and its engines firing is an example of:
   1. A pull decreasing speed.
   2. A push increasing speed.
   3. A pull increasing speed.
   4. A push decreasing speed.


6. A hockey player hitting a puck across the ice is an example of:
   1. A pull increasing speed.
   2. A push increasing speed.
   3. A pull decreasing speed.
   4. A push decreasing speed.


7. Which of the following best describes what happens when a force is applied to an object?
   1. The object always speeds up.
   2. The object's motion can change.
   3. The object always slows down.
   4. The object remains at rest.