Question

Worked Examples Journal, Part III PHY 2010 College Physics I Spring 2017 Worked Example Lesson 22 study the given problem and solution, then answer the questions regarding the problem STATEMENT OF THE PROBLEM A 1- kg ball, mL collides with a 3-kg ball, m2, as shown. The balls have initial velocities of v 1 initial 3 i m/s and 2 in 3 i m/s. Immediately after the collision v2 fl 1 initial 2 initia 2 i m/s, what is v 1 Before STRATEGY This is a one-dimensional Conservation of Linear Momentum problem. To use 1 initial Nr.itial the concept of conservation of momentum, we must ensure that there is no net external force acting on the system. Since 1) we are only interested in After what happens immediately before and after the collision, and 2) the collision is brief, we can assume that any external forces acting on the balls are negligible. 2 fir finan Because of these conditions, we say that linear momentum is conserved in collisions. (Note that linear momentum can be conserved during other 1 kg 3 kg interactions as long as the condition of no net external forces is met.) The 3 m/s 3 m/s initial Conservation of Linear Momentum equation is X nitial final and mv, 2 m/s 1 final 2 final specific to this problem, m1 1 initiai m 2 2 initia 1 v 1 fi m2 v 2finati As v v. the figure shows it is possible for one of the balls to have a negative velocity (oppositely directed) after or prior to the collision. IMPLEMENTATION We will designate a standard x-y coordinate system as shown. We will use the conservation of linear momentum equation and solve it for i1final.

Answer 1

Solution: (1) For using conservation of the momentum for collision external force must be zero otherwise momentum will change according to external force so our system become more complicated as well as momentum will not be conserved (2) Initial momentum PmVtla m22initil 13^ + 3x(-31) --6i m/s Final momentum -1x-12i +3x 2i -6i From the result Hence it is shown that linear momentum is conserved