Collisions - quantitative

In this activity you will be investigating the conservation of momentum of several collisions.

Remember ∑Pbefore = ∑Pafter

We will collide two dynamic trolleys and attempt to measure the speed just before and just after the collision Tracker. Set up the Trolleys on their track and position your laptop to video from above. You may want to clamp the laptop with retort stands and clamps

OBJECTIVES

To better understand the conservation of momentum.

To compare measured values with calculated values of momentum

MATERIALS

computer with tracker installed

2 x dynamic trolleys (mass = 273g approx.)

laminated plank and wedges

METHOD

• 1. Role a trolley along the trac to check how much friction is acting

  2. Adjust the height of the plank at one end to minimise the frictional force

Test 1

• 1. Push the first trolley into the second trolley

  2. Add 250 g to trolley 1 and repeat

  3. Add 250 g to the other trolley and repeat

Test 2

• 1. Rotate the trolleys so they meet at the Velcro/magnets

  2. Repeat the three scenarios with the collisions

DATA TABLE

Test I Transfer

Test 2 Connection

ANALYSIS

1. Draw diagrams of the before and after situation for both trials

2. Calculate the expected velocities for each scenario and complete the table below (a spread sheet would help here)

3. Compare your calculated values and the measured values. Try to explain the discrepancies.