# Physics-kinematics help-pellet and rifle

1. Dec 7, 2010

### MarcusB

1. The problem statement, all variables and given/known data
An air rifle can be used to fire small metal pellets which have a speed of about 150m/s on leaving the rifle. When an absorbent material is placed some distance from the rifle, the pellets are observed to penetrate the material to a depth of 3 to 4 cm.

Design an experiment to investigate how the depth of penetration varies with the speed of the pellet with a diagram and describing how

a) the speed of the pellets may be measured
b)The depth of penetration into the absorbent material may be measured
c)the speed of the pellets may be changed ( assuming the pellets leave the rifle with a fixed speed.)
d)any safety precautions for experiment

The foll. is available together with standard college lab equipment:
mounted air rifle
connecting wires
stopwatch
power supply unit
light gates
electronic timer
rule
sheets of absorbent material (eg cork)
thin aluminum foil

expected results

2. Relevant equations

?

3. The attempt at a solution

i guess the light pipes can be used to measure the speed of the bullet but how do you vary the speed?
can you use the foil to slow the bullet???

2. Dec 7, 2010

### Staff: Mentor

There are at least two other ways to vary the speed of the bullet hitting the target. One involves the equation TE = PE + KE. What do you think that method would be? And does it suggest another method?