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Why Can Momentum Be Conserved in One Direction but Not Another?

Why Can Momentum Be Conserved in One Direction but Not Another?

by Raul Barrea | Oct 15, 2026 | article, Energy & Momentum

Foundational Physics Short Answer: Momentum is conserved separately in each direction only when the net external impulse in that direction is zero. During a brief collision, an external force can change the horizontal momentum of an object without appreciably changing...
Can Total Momentum Be Zero Even When Objects Are Moving?

Can Total Momentum Be Zero Even When Objects Are Moving?

by Raul Barrea | Oct 15, 2026 | article, Energy & Momentum

Foundational Physics Short Answer: Yes. Total momentum can be zero while objects are moving because momentum has direction. If the momenta of different objects are equal in magnitude and opposite in direction, they cancel when added, even though each object still has...
Where Does the “Lost” Kinetic Energy Go in an Inelastic Collision?

Where Does the “Lost” Kinetic Energy Go in an Inelastic Collision?

by Raul Barrea | Oct 15, 2026 | article, Energy & Momentum

Foundational Physics Short Answer: The “lost” kinetic energy in an inelastic collision has not disappeared. Some of the energy of visible motion becomes deformation, vibrations, thermal energy, and sometimes sound. Even two Velcro carts that stick together quietly can...
Why Is Momentum Conserved When Kinetic Energy Is Not?

Why Is Momentum Conserved When Kinetic Energy Is Not?

by Raul Barrea | Oct 15, 2026 | article, Energy & Momentum

Foundational Physics Short Answer: Momentum can stay the same during a collision even when kinetic energy decreases because the two quantities follow different conservation rules. If the net external impulse on the colliding objects is negligible, their total momentum...
Why Doesn’t Gravity Do Work on a Satellite in a Circular Orbit?

Why Doesn’t Gravity Do Work on a Satellite in a Circular Orbit?

by Raul Barrea | Oct 15, 2026 | article, Rotation & Gravitation

Foundational Physics Short Answer: In an ideal circular orbit, gravity pulls the satellite toward Earth’s center, but the satellite moves sideways along the circle. The pull stays perpendicular to the direction of motion. That means gravity changes the satellite’s...
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