CIE A Level Maths: Mechanics复习笔记5.1.3 Collisions - Multiple Collisions
Collisions - Multiple Collisions
Can there be multiple collisions?
- After?two objects collide?it is possible that one (or both) of them?collides with something else?such as
- A?third object
- A?wall?(perpendicular to the motion)
- Deal with?each collision separately?and use the steps for direct collisions
Can there be a second collision between the original two objects?
- Let A, B and C be three objects travelling in the?same straight line?and suppose?A and B collide directly?and subsequently?B and C collide directly
- After the collisions between?A and B?and?B and C?there will be a?second collision?between?A and B if:
- One?is?stationary?and the?other?is?travelling towards?it
- Both are?travelling in opposite?directions?towards?each other
- Both are?travelling in the same?direction and the?one in front is slower?than the one behind
- The process is?similar?if object?C is a wall
- After?B collides with the wall?its?direction will be reversed?so it will be travelling?towards A
- B will?collide with A?again if its?velocity in that direction?is?greater?than the velocity of A in that direction
- To help you work out the speed of B after hitting the wall you will be given extra information such as the?change in momentum of B?or?loss in kinetic energy
Worked Example
Exam Tip
- These questions can be difficult to visualise in your head so draw simple diagrams to show each collision.
- Use common sense, think how many possible (or impossible) ways there are for objects to move after the first collision. You will often have to consider the speed of one or more objects to decide if a second or third collision is possible.
- Questions can ask you to find the loss in kinetic energy so be sure to find the total kinetic energy?before?a collision and compare it to the total kinetic?energy?after a collision.
- These questions can involve lots of algebra, negatives and inequalities so do not rush them as you might make a silly mistake which can affect subsequent parts.
转载自savemyexams
国际竞赛真题资源免费领取
美高学分项目重磅来袭！立即了解
