Imulse and Momentum

Imulse and Momentum - Chapter 9. Impulse and Momentum...

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Chapter 9. Impulse and Momentum Chapter 9. Impulse and Momentum Chapter Goal: To introduce the ideas of impulse and momentum and to learn a new problem-solving strategy based on conservation laws.
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Ch. 9 Student Learning Objectives • To understand interactions from the new perspective of impulse and momentum . • To learn what is meant by an isolated system . • To apply conservation of momentum in simple situations. • To understand the basic ideas of inelastic collisions, explosions, and recoil.
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Impulsive Forces and Newton’s 2nd Law An impulsive force can be defined as a large force exerted during a small interval of time. Collisions and explosions are examples of impulsive forces. Until now, we’ve been using Newton’s Law (and kinematic equations) for constant forces and accelerations. Impulsive forces are not constant.
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Impulsive Forces and Newton’s 2nd Law F net-x = ma x This law applies to non-constant forces as well F x (t) = ma x (t) so F x (t) = m dv x / dt multiplying through by dt: F x (t) dt = m dv x . Now take the integral of both sides: = x dv m
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Impulsive Forces and Newton’s 2nd Law This can be written as: = mv f – mv i which is how Newton actually wrote it in the first place. You can solve for the velocity of an object, even if the acceleration is not constant. = x dv m
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Impulse Impulse The impulse upon a particle is defined as: Impulse has units of N-s Newton’s Law tells us that the impulse exerted on an object is equal to ∆ mv Impulsive forces are often short! Time is sometimes given in units of ms or µs.
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Impulse Problem (EOC #5) What value of F max gives an impulse of 6 N-s? A..75 N B.1.5 N C.750 N D.1500 N
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Impulse Momentum Theorem (an alternate version of Newton’s 2 nd Law) J x = ∆p x where change in momentum = ∆p x = m f v f – m i v i Momentum and change in momentum are vector quantities.
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A. 30 kg m/s. B.
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This note was uploaded on 10/26/2011 for the course PHYS 221 taught by Professor Tedeschi during the Spring '09 term at South Carolina.

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Imulse and Momentum - Chapter 9. Impulse and Momentum...

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