Physics 1401A/B Lecture Notes - Lecture 16: One Direction

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scarlethound445

2 Jan 2019

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A collision changes the velocities of the objects involved. Since the kinetic energy of an object depends on its speed, the kinetic energy of the object also changes as a result of the collision. Elastic collisions a collision in which momentum and kinetic energy are conserved. An extremely elastic rubber ball is compressed during a collision, and this compression stores energy in the ball just as energy is stored in a compressed spring. In an ideal rubber ball, all of this potential energy is turned back into kinetic energy when the ball decompresses (springs back) at the end of the collision. Inelastic collisions a collision in which momentum is conserved, but kinetic energy is not conserved. The kinetic energy is transformed into other forms, such as thermal energy or sound energy. Ideal collision in which external forces are minimized to the point where momentum and kinetic energy are perfectly conserved.

Related Questions

In this problem, let us consider that the two moving objects undergo collision such that after the collision, the objects stick together and travel off as a single unit. This is totally inelastic form of collision.

You are probably familiar that "momentum is conserved" in an inelastic collision. Solve the questions given below to clarify the meaning and implications of "momentum is conserved."

1)What physical quantities are conserved in this type of inelastic collision?
a) the magnitude of the momentum only
b) the net momentum (considered as a vector) only
c) the momentum of each object considered individually

2) Two cars of equal mass collide inelastically and stick together after the collision. Before the collision, their speeds are V1 and V2 . What is the speed of the two-car system after the collision?
a) V1+V2
b) V1-V2
c) V2-V1
d)(V1V2)^(1/2)
e) (1/2)(V1+V2)
f)(V1+V2)^(1/2)
g)The answer depends on the directions in which the cars were moving before the collision.

3) Two cars collide inelastically and stick together after the collision. Before the collision, the magnitudes of their momenta are P1 and P2 . After the collision, what is the magnitude of their combined momentum?

a) P1+P2
b) P1-P2
c) P2-P1
d)(P1P2)^(1/2)
e) (1/2)(P1+P2)
f)(P1+P2)^(1/2)
g)The answer depends on the directions in which the cars were moving before the collision.

4) Two cars collide inelastically and stick together after the collision. Before the collision, their momenta are p1 and p2. After the collision, their combined momentum is vector p. Of what can one be certain?

a) Vector P= p1+p2
b) Vector P= p1-p2
c) Vector P= p2-p1

aquamarineswan704

In this problem we will consider a collision of two moving objects such that after the collision, the objects stick together and travel off as a single unit. The collision is therefore completely inelastic.

You have probably learned that "momentum is conserved" in an inelastic collision. But how does this fact help you to solve collision problems? The following questions should help you to clarify the meaning and implications of the statement "momentum is conserved."

1)What physical quantities are conserved in this collision?
a) the magnitude of the momentum only
b) the net momentum (considered as a vector) only
c) the momentum of each object considered individually

2) Two cars of equal mass collide inelastically and stick together after the collision. Before the collision, their speeds are V1 and V2 . What is the speed of the two-car system after the collision?
g)The answer depends on the directions in which the cars were moving before the collision.

3) Two cars collide inelastically and stick together after the collision. Before the collision, the magnitudes of their momenta are P1 and P2. After the collision, what is the magnitude of their combined momentum?

a) P1+P2
b) P1-P2
c) P2-P1
d)(P1P2)^(1/2)
e) (1/2)(P1+P2)
f)(P1+P2)^(1/2)
g)The answer depends on the directions in which the cars were moving before the collision.

4) Two cars collide inelastically and stick together after the collision. Before the collision, their momenta are p1 and p2. After the collision, their combined momentum is vector p. Of what can one be certain?

a) Vector P= p1+p2
b) Vector P= p1-p2
c) Vector P= p2-p1

taupecamel748

Two identical steel balls, each of diameter 25.4 mm and moving in opposite directions at 5 m/s, run into each other head-on and bounce apart. Prior to the collision, one of the balls is squeezed in a vise while precise measurements are made of the resulting amount of compression. The results show that Hooke's law is a fair model of the ball's elastic behavior. For one datum, a force of 16 kN exerted by each jaw of the vise results in a 0.2 mm reduction in diameter. The diameter returns to its original value when the force is removed. (a) Modeling the ball as a spring, find its spring constant. (b) Does the interaction of the balls during the collision last only for an instant or for a nonzero time interval? State your evidence. (c) Compute an estimate for the kinetic energy of each of the balls before they collide. (d) Compute an estimate for the maximum amount of compression each ball undergoes when the balls collide. (e) Compute an order-of-magnitude estimate for the time interval for which the balls are in contact.

Physics 1401A/B Lecture Notes - Lecture 16: One Direction

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