Use the photogate timer in the PULSE mode. For each run, line up the
leading edge of the car with the starting number on the scale.
Release the car and simultaneously activate the timer by pressing
the Start/Stop button on the timer. The car will deactiva
In this laboratory, you will study several types of collisions between two objects and
analyze the momentum exchange taking place during the collisions. One type, called
elastic collision, encompasses only collisions in which the kinetic energy is also
Newton then stated three laws that included momentum as a key player. The first law
states that if in an inertial frame of reference
, the net external force acting on a point-like object is zero, the object must be moving at
a constant velocity, i.e.,
Mass of the steel ball: m= 62.7g
Diameter of steel ball: d= 2.467cm
Mass of pendulum: M = 219.0g
Effective Length of pendulum: l = 24.6cm
Change in the height of the pendulum: h , measured in cm
Velocity of pendul
Make sure the track is level.
If the track is set at an angle with respect to the horizontal, it will not be
possible to determine what that angle is.
Level the track by
adjusting the appropriate leveling screws. The track is level when
the car does
When setting up for measuring vA and vB, make sure that the photogates are far enough
along the track so that the spring is no longer acting to push the cars apart
when the cars pass through those gates; otherwise, during the time that
Recall, the momentum equation is: m1v1,i =(m1 +m2 )vf , so we need uncertaintiesfor
both masses and velocities
[(m1 +m2)]2 =(m1)2 +(m2)2
vv112 =LL112 +t1t12
pp112 =mm112 +vv112 .
Following the collision:
vvf f 2 L112 +tt