PHYS 101 Chapter Notes - Chapter 7: Elastic Collision, Inelastic Collision, Isolated System

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turquoisescorpion358

15 Dec 2017

School

Simon Fraser University

Department

Physics

Course

PHYS 101

Professor

Eldon Emberly

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Document Summary

Linear momentum: product of the objects mass and velocity. P = mv: p = momentum (vector), kg m/s, v = velocity, m = mass. The more momentum an object has, the harder it is to stop it. Requires greater or equal opposite force to stop the object with momentum. The rate of change of momentum of an object is equal to the net force applied to it. If no net external force acts on a system, total momentum of system is a conserved. Case with ball collision: m1v1 + m2v2 = m1"v1" + m2"v2", momentum before collision = momentum after collision. Falling rock doesn"t conserve momentum because force of gravity (external force) changes rock"s momentum. If earth is part of system (force of gravity) then total momentum between rock & earth are conserved. During collision, force from 2 objects spikes up from 0 at moment of contact (large force in short time)

Related Questions

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

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

Object A collides on a horizontal frictionless surface with an initially stationary target, object X. The initial and final velocities of object A are shown. The final velocity of object X is not given.

a). At an instant during the collision, is the net force on object A zero or non-zero?

b) [During the collision, is the momentum of object A conserved? Explain. Is the momentum of the system consisting of objects A and X conserved? Explain. On the same horizontal surface, object C collides with an initially stationary target, object Z. The initial speeds of objects C and A are the same, and m_x = m_z > m_A = m_c. After the collisions, object C moves in the direction shown and has the same final speed as object A. In the space below, copy the vectors v_C1 and v_cr with their tails together. Use these vectors to draw the change in velocity vector for glider C, Delta v_c. Is the magnitude of the change in velocity vector of object A greater than, less than, or equal to the magnitude of the change in velocity vector of object C? Explain? Is the magnitude of the change in the momentum vector of object A greater than, less than, or equal to the magnitude of the change in the momentum vector of object C? Explain? Is the final speed of object X greater than, less than, or equal to the final speed of object Z? Explain. Consider the following incorrect statement: Gliders A and C have some change in momentum. They have the same mass, and because they have the same initial speed and same final speed. Delta-v is the same for each of.them." Discuss the error(s) in the reasoning.

sangriaporcupine175

PHYS 101 Chapter Notes - Chapter 7: Elastic Collision, Inelastic Collision, Isolated System

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