
Lecture Demonstrations  
Mechanics 

M28: Falling Bodies 

Purpose: To demonstrate the relation y=(1/2)gt^{2} 

Description: 

The apparatus consists of a cord approximately 3.5 m long with weights tied to it at such spacings to produce constant time intervals between the sounds of the weights hitting the floor. The length of the cord is about 3.5 m and the spacings of the weights are calculated to produce a time interval of 0.15 sec. The class should first be shown that the weights are distant from the bottom y according to the relation y = (1/2)gt^{2} for Dt = 0.15 sec. Thus, since t = Sum[ (Dt)_{i} ], the following table shows the predicted y values for constant Dt:
t (sec) y (cm) 0.00 0 0.15 11 0.30 44 0.45 99 0.60 176 0.75 276 Stand on the desk and hang the cord over a pie tin. When released, the sound of the weights hitting the tin will occur at constant intervals. 
Equipment List:  Storage Location: CHEMP 130A 

Cord, Weights, Metal plate  D5.3 
References: 
Manual: None  Setup Notes: M28  PIRA #: 
Manufacturer(s): VT  Other school's Demonstration web pages 
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