Ballistic Pendulum
Important Note concerning a Measurement
When the projectile is shot into the pendulum, the pendulum swings upward and is caught at its highest point by the pawl P which engages a tooth in the curved rack R.
The toothed surface of the rack lies on the arc of a circle having its cneter in the axis of suspension of the pendulum.
A scale along the outer edge of the rack provides a means for noting and recording the position of the pendulum after each shot.
Take the average of the position after shooting the ball 3 times. This is the highest position of the pendulum.
Raise the pendulum until its pawl is engaged in the tooth correspoinding most closely to the mean value and measure the the elevation of the center of the ball above the reference point. This is h2
Lower the pendulum so that it hangs freely and measure the distance from the center to the reference point. This is h1.
h2 - h1 is the vertical distance through which the center of the ball is raised after shooting the ball.
A picture of the Ballistic Pendulum is on the right
This lab addresses 2 conservation laws:♦ Conservation of linear momentum ♦ Conservation of mechanical energy
Description of the lab♦ The gun on the right of the picture will fire a brass ball (B) that is initially on a rod (H). ♦ The ball will impact and become lodged in a cylindrical bob (C). ♦ The pendulum (M) will then swing upwards a certain distance that can be measured with the scale (R). ♦ You need to break the problem into two parts and apply the appropriate conservation law for each part.
Mass of Components: Brass ball (B): 70 g
Pendulum system (arm K and bob C): 345 g |
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Requirements
Part a:
Data collected for use in calculations:
♦
Reference point used:
________________________________________________________________
♦
Initial height of the ball(h1) above the reference point:
_____________________________________________
♦
Final height of the ball (h2) above the reference
point:______________________________________________
♦
Other (if
appropriate):_________________________________________________________________
Calculation of velocity of the ball - Show all calculations
Explain why it necessary to break the problem into 2 parts.
Sources of error
Part b:
Data collected for use in calculations - label each along with the measured
value
Calculatre the horizontal distance travelled by the ball using the
velocity calculated in part a - show all calculations
Measured horizontal distance travelled by the ball.
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Sources of error