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chapt 6

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Terms in this set (20)

  • What is momentum?

    Momentum is a property of moving objects, defined as the product of an object's mass and velocity.

  • How is momentum calculated?

    Momentum is calculated by the formula \(p = mv\), where m is mass and v is velocity.

  • What happens to momentum when the speed of an object doubles?

    The momentum doubles because momentum is directly proportional to velocity.

  • Define impulse in physics.

    Impulse is the product of force and the time interval over which it acts, expressed as \(Impulse = Ft\).

  • How does impulse affect momentum?

    Impulse changes momentum; the greater the impulse, the greater the change in momentum.

  • Why is it better to hit a haystack than a concrete wall when a car is out of control?

    Because the haystack increases the time over which momentum changes, reducing the force experienced by the car.

  • What is the effect of increasing the time of contact during a collision?

    Increasing contact time reduces the average force exerted, resulting in a smaller force for the same change in momentum.

  • Explain the concept of conservation of momentum.

    In the absence of external forces, the total momentum of a system remains constant.

  • What happens to the momentum of a cannon and cannonball when the cannon is fired?

    The cannonball gains forward momentum, and the cannon recoils with equal momentum in the opposite direction.

  • What is an elastic collision?

    An elastic collision is one where colliding objects rebound without lasting deformation or heat generation.

  • What is an inelastic collision?

    An inelastic collision results in deformation and/or heat generation during the collision.

  • How does the speed of two coupled freight cars compare to the initial speed of one car before collision?

    The speed of the coupled cars is half the initial speed of the moving car due to doubled mass and conserved momentum.

  • How do you find combined momentum when objects collide at angles?

    Use vector addition, such as creating a parallelogram of the momentum vectors, to find the combined momentum.

  • What is the impulse when force acts for twice as long?

    The impulse is doubled because impulse equals force multiplied by time.

  • Why does a cannonball shot from a long barrel have greater speed?

    Because the force acts over a longer time, producing a greater impulse and thus greater momentum.

  • What happens to the force when momentum changes over a short time?

    A short time interval produces a large force for the same change in momentum.

  • Why do objects that bounce experience greater impulses?

    Because the momentum changes direction, requiring a greater impulse than simply stopping the object.

  • What is the relationship between impulse and change in momentum?

    Impulse equals the change in momentum, expressed as \(Ft = \Delta mv\).

  • How does bending knees when landing reduce force?

    Bending knees increases the time over which momentum decreases, reducing the force exerted by the ground.

  • What happens to the momentum of a system when internal forces act?

    Internal forces cancel out, so they do not change the total momentum of the system.