Question

Consider the situation where one IOLab device rolls into another stationary IOlab device and they stick together and they roll off together. When answering the following questions, answer them specifically for this situation.

How could you calculate the total momentum before the collision?      

How could you calculate the total momentum after the collision?      

How could you calculate the total kinetic energy before the collision?      

How could you calculate the total kinetic energy after the collision?      

(Extra information: the IOLab device can generate both Force/Time graphs and Velocity/ Time graphs)

Answer 1

After getting hands on IOlab device the first task would be to measure its mass (both the masses, if two different versions of IOlab devices are being used)

As the devices can generate velocity vs time graphs so we know the velocities before and after the collision.

Having found the two important parameters i.e., masses and velocities, now we can tackle the questions.

How would you calculate the total momentum before collision?

The individual momentum of each IOlab device can be found by multiplying their masses with their velocities just before collision. Then by adding the individual momentum of the two devices we would get the total initial momentum or the total momentum before collision.

How would you calculate the total momentum after collision?

After collision the two IOlab devices stick together and move with a single velocity. This velocity is known through the velocity vs time data. Now the masses of both devices are added and multiplied with the velocity with which they move after collision. This gives the total momentum of the system after the collision.

How would you calculate the total kinetic energy before collision?

Just like the momentum the total kinetic energy is the sum of the individual kinetic energies of the two devices. Mass and velocities before collision are known so we find the individual kinetic energy by the formula . Then we add them together to obtain the total kinetic energy of the system before collision.

How would you calculate the total kinetic energy of the system after collision ?

The total kinetic energy after collision is found using the formula , by adding the individual masses and multiplying with the square of the common velocity.