LO1

1. Physics 101 Learning Object 1
Horizontal Mass Spring Systems
There are four springs that are totally the same. Their left sides are connected to walls, and their
right sides are connected nothing. There are six exactly same wood blocks.
Question: the four springs and six blocks are put in three different ways on the totally same floors
(As shown by graph A ,B ,C) . All the springs are compressed until they are same long with each
others. Then let the springs push the blocks away. Which two blocks goes further?(regardless air
resistance)
A. (the blocks are tired together) B.( the blocks are tired together)
C.(there are two same springs and the blocks are tired together) D.(force made by spring is yellow,
friction force is green)
Answer: A and B will pass the same distance,and C will pass the longest distance.
Explanation : After the springs push blocks out, the speeds of them decrease until they stop.
Friction force is the only force that go opposite direction against the “pushing force”(as shown in
graph D). A and B go the same distance, because the force of the springs are the same and we do
not need to think about the air resistance. The only two things we need to think about is the force
created by the springs and the friction force. The force made by springs are the same.These two
blocks have the same weight, so the friction force are the same. As a result , they go the same

2. distance. Although for C, the friction force is the same as in A and B , the spring force is bigger
than that in A and B. Consequently, block in C goes further.