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Explore the concepts of elastic and inelastic collisions, where objects either stick together or separate upon impact. Learn how kinetic energy is transformed and conserved, with examples of perfectly inelastic and elastic collisions.
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Momentum and Collisions Elastic and Inelastic Collisions
Collisions • When two objects come together • In some collisions, the objects stick together • Perfectly Inelastic • In other collisions, the objects separate • Elastic • Total kinetic energy is usually not conserved because kinetic energy is converted to internal energy as the objects deform
Perfectly Inelastic Collisions • Perfectly inelastic collision – a collision in which two objects stick together and move with a common velocity after colliding • An arrow sticking into a target • Mass of the first object * initial velocity of the first object + mass of the second object * initial velocity of the second object equals the final velocity * the sum of the two object’s masses • m1v1,i + m2v2,i = (m1+m2)vf
Perfectly Inelastic Collisions • Remember to assign positive and negative values based on direction • Kinetic energy is not constant in perfectly inelastic collisions
Elastic Collisions • Elastic collision – a collision in which the total momentum and total kinetic energy remain constant • m1v1,i + m2v2,i = m1v1,f + m2v2,f • ½m1v1,i2 + ½m2v2,i2 = ½m1v1,f2 + ½m2v2,f2
Inelastic Collisions • Most collisions are neither elastic nor perfectly inelastic • Fall into a third category • Inelastic collisions – the colliding objects bounce and move separately after collision, but total kinetic energy decreases