Question

Make Your Own Model In this lab, you will be modeling various collisions and taking measurements as objects collide. In doing so, you will hopefully become more comfortable with momentum, energy, and the conservation laws associated with these quantities. In this Pre-Lab, rather than focusing on momentum and energy, we will focus on modeling. (Practice problems involving momentum and energy can be found throughout your textbook.) Taking the expression "toy model" somewhat literally, you will discuss how you could model children on a playground. Read This: For each of the two situations given below, do the following: a) Describe how you could simplify the objects (i.c. the child and the playground equipment) b) Describe how you could simplify the interaction(s). c) Describe one limitation of your model. Read This: If you need some inspiration, you could re-read the examples of the car and the baseball. PLI. A child goes down a slide. PL2. A child rides a merry-go-round, holding onto a bar near the outside edge. (See Figure 1.) End of Pre-Lab Part 1: Modeling Collisions Figure 1: Children on a merry-go-round. Previous Next Dashboard Calendar To Do Notifications Inbox

Answer 1

1)

a) The objects can be modeled as a mass on a slide. The assumptions we can make are that the child is having a uniform mass and the slide is having uniform slant ( a straight slide with no curves)

b) To simplify the situations, the friction, any movement of the child and air resistance can be neglected, so that the only force acting on the child is gravity.

c) The limitations of the model are the assumptions made above. The child is not a uniform mass, and the shape of the child will cause different values of air resistance at different times. Also, the friction is always present. Another limitation is that the slide is never straight, as this is very dangerous for the child, and can cause accidents.

2)

a) Here also, we can assume the child as a uniform mass. The merry go round can be assumed to be a perfect disc, rotating about its center of mass, and that there is no friction or other dissipative forces.

b) To simplify the situation, we have to assume that the merry go round is rotating with a uniform speed,but with not enough speed so that the child will be thrown away from the merry go round. Another assumption could be that the hold of the child is very strong, that he does not move due to the rotation of the merry go round.

c) The limitations to this model is that any object can not be fixed perfectly at its center of mass, and so the rotation will be different than ideal case. There will also be friction at the point of contact, which is necessary to hold the merry go round in position when it is not rotating.

The child's hold is also not very strong. So he could move in any random direction during the rotation of the merry go round.