The following is an extract from a student's report of an experiment to verify the principle of conservation of momentum - Leaving Cert Physics - Question 1 - 2011

The student used a set of scales to measure the mass of each trolley. This could involve balancing the trolley on a weighing scale, following the principles of equilibrium, or using a digital scale for precise measurements.

To determine the velocity of the moving trolley, the student employed the equation:
$velocity = \frac{distance}{time}$
where distance was measured along the runway and time was recorded using the timer. By measuring both the total track distance and the time taken to traverse that distance, the velocity of the trolley can be calculated accurately.

The momentum of a trolley was determined using the formula:
$momentum = mass \times velocity$
Here, the mass is obtained from the weighing scale measurement and the velocity is calculated from the time and distance measurements.

To verify the principle of conservation of momentum, the student compared the total momentum before and after collisions involving the trolleys. By measuring the momentum of each trolley before and after the interaction, the student ensured that the total momentum was constant, confirming the principle. This can be summarized as:
$m_1v_1 + m_2v_2 = m_1v_1' + m_2v_2'$
where m represents mass and v represents velocity before (subscript 1) and after (subscript 2) the interaction.