Conservation of Momentum: Trolleys

Also called

conservation of momentum · momentum · law of conservation of momentum · trolleys · collision · spring between carts · recoil · bullet and block · inelastic collision · mass times velocity · p = mv · second law of motion · isolated system · संवेग · संवेग संरक्षण · टक्कर

Topics

• Momentum is mass × velocity (p = mv); it has the same direction as the velocity.
• In an isolated system the total momentum before an event equals the total momentum after it.
• Two carts pushed apart by a spring start with zero total momentum, so they gain equal and opposite momenta.
• With equal masses the carts move apart at equal speeds; a cart of twice the mass moves off at half the speed.
• When a moving cart sticks to a resting cart of equal mass, the pair moves on at half the original speed.
• A bullet that buries itself in a block shares its momentum with the block, so the heavy block moves off slowly.
• The forces the two carts exert on each other are equal and opposite, so the momentum one loses the other gains.
• On the momentum board the blue and red bars laid end to end have the same total length before and after.

About this model

A GLB file of about 235 KB, shown in Lably's 3D viewer and, on a phone, placed in your room with AR. Credit: Model, science and animation: Lably (built procedurally with three.js; no downloaded meshes). | CC BY 4.0. Original geometry and animation made for Lably.

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