19-April-2017: Lab 14: Impulse-Momentum activity

Lab 14: Impulse-Momentum activity

Author: Tian Cih Jiao

Lab Partner: Weisheng Zhang, Kitarou

Date: Apri 19, 2017

Purpose of the lab: Observe/verify the impulse momentum theorem

Theory/Introduction:

EXPT 1: Observing Collision Forces That Change With Time

First, we replace one end of force senor by a rubber stopper. Then we give a push to the cart so that it has a V0, after the collision, it has a Vf.

According to impulse-momentum theorem, change in momentum of the cart = net impulse.

So m * (Vf - V0) = The integral of F(t)

We can calculate the integral through the graph draw by the force sensor.

EXPT 2: Larger Momentum Change

Add some hundreds of grams of mass on the cart and do the same process in Part 1.

EXPT 3: Inelastic Collision

Replace the spring with a plasticine so that the cart will stop after collision. 

Apparatus/Experimental procedure:

Left is spring, right is plasticine






Measured data:
The mass of the cart is measured to be 0.64 kg originally (1.14 kg if a 500-gram mass is installed onto the cart).

EXPT 1 Graph:


EXPT 2 Graph:


EXPT 3 Graph:


Analysis:
EXPT 1: Integral is 0.7022, which is Impulse. It should be equal to change in momentum. Change in momentum = 0.64 * delta v = 0.64 * 1.124 = 0.71936
EXPT 2: Integral is 0.9844, Change in momentum = 1.14 * 0.844 = 0.96102
EXPT 3: Integral = 0.3328, Change in momentum = 0.64 * 0.508 = 0.3253

Conclusion:
From the lab result, we can get that the Impulse-momentum theorem applies to elastic collision but not to inelastic collision.