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Why Can Two Objects Have the Same Kinetic Energy but Different Momenta?

Why Can Two Objects Have the Same Kinetic Energy but Different Momenta?

by Raul Barrea | Oct 22, 2026 | article, Energy & Momentum

Foundational Physics Short Answer: Two objects can have the same kinetic energy but different momenta because kinetic energy depends on mass and the square of speed, while momentum depends on mass and velocity. A heavier, slower object and a lighter, faster object can...
Why Does a Longer Stopping Distance Reduce the Average Force in a Collision?

Why Does a Longer Stopping Distance Reduce the Average Force in a Collision?

by Raul Barrea | Oct 22, 2026 | article, Energy & Momentum

Foundational Physics Short Answer: For the same initial speed and the same final speed of zero, a longer stopping distance reduces the magnitude of the average stopping force along the motion. The object must lose the same kinetic energy, but the force can act over...
Why Do Two Objects Experience Equal Forces but Different Accelerations During a Collision?

Why Do Two Objects Experience Equal Forces but Different Accelerations During a Collision?

by Raul Barrea | Oct 22, 2026 | article, Energy & Momentum

Foundational Physics Short Answer: During a collision, each object pushes on the other with an equal-magnitude, opposite-direction force, as Newton’s third law says. Their accelerations can still be different because acceleration also depends on mass. For the same...
Why Does a Rocket Accelerate in Empty Space?

Why Does a Rocket Accelerate in Empty Space?

by Raul Barrea | Oct 22, 2026 | article, Energy & Momentum

Foundational Physics Short Answer: A rocket can accelerate in empty space because it expels exhaust backward. The rocket pushes on the exhaust, and the exhaust pushes the rocket forward. The rocket does not need air, the ground, or anything outside it to push against....
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...
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