Physics Chapter 3 Quiz

Newton's Third Law

• For every action, there is an equal and opposite reaction.
• This means that forces always come in pairs.

Kinetic Energy

• Kinetic energy is the energy an object possesses due to its motion.

Conservation of Energy

• The principle of conservation of energy states that energy cannot be created or destroyed, only transferred or transformed.

Perfectly Elastic Collisions

• In a perfectly elastic collision, both momentum and kinetic energy are conserved.

Matching Terms to Definitions

• Momentum: The product of an object's mass and velocity.
• Kinetic Energy: The energy an object possesses due to its motion.
• Elastic Collision: A collision where both momentum and kinetic energy are conserved.
• Inelastic Collision: A collision where momentum is conserved, but kinetic energy is not.

Newton's Third Law

• For every action, there is an equal and opposite reaction.

Kinetic Energy

• Kinetic energy is the energy an object possesses due to its motion.

Conservation of Energy

• The principle of conservation of energy states that energy cannot be created or destroyed, only transformed from one form to another.

Elastic Collisions

• In a perfectly elastic collision, both momentum and kinetic energy are conserved.

Definitions

• Impulse: The change in momentum of an object.
• Power: The rate at which work is done.

Momentum and Energy

• Momentum: A measure of an object's mass in motion.
• Energy: The ability to do work.

The Law of Conservation of Momentum

• The total momentum of an isolated system remains constant: This means that momentum cannot be created or destroyed, only transferred between objects within a system.
• This law stems directly from Newton's Laws of Motion.
• Momentum is defined as the product of an object's mass and its velocity: p = mv, where p is momentum, m is mass, and v is velocity.
• The formula for the Law of Conservation of Momentum is p = p' or m₁v₁ + m₂v₂ = m₁v₁' + m₂v₂': This equation shows that the sum of the momentum of all objects in an isolated system (no external forces) is constant.
• Impulse is the amount of force applied on an object over a certain amount of time (J=FΔt), and it's equal to the change in momentum (J=mΔv=Δp): This is called the impulse-momentum theorem.

Real-World Applications

• A car collision: The sum of the momentums of the two cars before the accident is equivalent to the sum of their momentums after the accident.
• A pirate ship firing a cannonball: The momentum of the cannon and cannonball before firing is zero, and the momentum of the cannonball traveling horizontally at a specified velocity is compensated by the recoil velocity of the cannon.
• A truck hitting a parked car: The total momentum before the collision (truck moving) equals the total momentum after the collision (truck and car moving).

Example Calculations

• A 6000 kg truck moving at 10 m/s hits a 1000 kg parked car, causing it to move at 15 m/s: The truck's velocity after the collision can be calculated using the conservation of momentum equation.
• A cannonball fired from a pirate ship (given masses and velocities): The recoil speed of the cannon can be determined using the conservation of momentum principle.

Key Concepts

• Newton's Third Law: Every action has an equal and opposite reaction.
• Newton's Second Law: Force equals mass times acceleration (F=ma).
• Momentum is a vector quantity: It has both magnitude (amount) and direction.

Understanding Momentum

• A larger object moving faster has more momentum than a smaller or slower object.
• In a closed system, the total momentum stays constant even though individual objects may transfer it.
• In collisions, momentum is transferred between objects.
• Momentum is conserved even when an object stops (like a car hitting a brick wall), because the momentum is transferred to other objects (like the wall and the Earth).

Summary

The Law of Conservation of Momentum, a fundamental principle in physics, helps explain the movement of objects in a closed system. It states that momentum is neither created nor destroyed but is transferred between objects within a system. By applying this principle, we can analyze and calculate the movement of objects in various scenarios, from collisions to explosions.