Physics 1101
Experiment 11
Name_________________________________
Pre Lab
Instructor name _________________________
1. What is the difference between an elastic collision and a completely inelastic collision? Please
give detailed explanation. Under what conditions is the conservation of momentum applicable?
Explain your answer thoroughly. (8 pts)
2. What is the purpose of leveling the track and adding paper clips to the end of the string? In this
experiment, what do variables in 𝑥1 and 𝑥2 stand for? Why might it be necessary to ignore some
of the data points just before and just after the collision? Explain your answer thoroughly. (7 pts)
3. For a completely inelastic collision, the fractional change in kinetic energy can be found as a
function of the masses of the projectile and target carts only. Show that the fractional change in
kinetic energy is given by
∆(𝐾𝐸)
𝐾𝐸𝑖
=
(𝐾𝐸𝑓 − 𝐾𝐸𝑖 )
𝐾𝐸𝑖
= −
𝑀
. What is the significance of the
(𝑚+𝑀)
negative value for the fractional change in kinetic energy? Please show every step of calculation.
(15 pts)
4. A bullet of mass 0.02050 𝑘𝑔 collides inelastically with a wooden block of mass 23.00 𝑘𝑔,
initially at rest. After the collision the system has speed of 1.230 𝑚/𝑠. What was initial speed of
the bullet? What fraction of energy was transformed to other forms of energy? Please show every
step of calculation. (15 pts)
5. On a touchdown attempt, 97.00 𝑘𝑔 running back runs toward the end zone at 3.850 𝑚/𝑠. A
117.0 𝑘𝑔 line-backer moving at 4.280 𝑚/𝑠 meets the runner in a head-on collision. If the two
players stick together, a) what is their velocity immediately after collision? b) What is the kinetic
energy of the system just before the collision and a moment after the collision? Please show every
step of calculation. (15 pts)