Welcome Investigators! Today: 1.Please turn in your “Don’t Lose Your Marbles” Lab packet, graph and written wrap-up if you haven’t already 2.Return Energy Quiz and other work 3.More Marbles! – Marbles and Ramps Lab

Some Adjustments to the lab sheet ______ marbleDistance moved by Styrofoam cup (cm) Drop height (cm)Trial 1Trial 2Trial 3Average (choose) On one graph Graphing: A. The average distance moved by the cup (DV) and the drop height (IV) B. The average distance moved by the cup and the number of marbles

Marbles and Ramps Day 2 1.Complete your graph(s) – It is ok to put all your data on one graph, just use a different color for each number of marbles = one marble = two marbles = three marbles 2.Use your graphs to answer the questions on the lab sheet

So… If energy is the ability to do work or cause change – Q: What was the “work” we measured? – A: The distance the cup moved – How did the amount of work change as you added mass (added marbles)? – Were there any patterns to how the work changed? For example if you doubled the mass, did the work done double? – How did the amount of work change as you increased the drop height? – If you doubled the drop height what happened to the work done?

Calculating Kinetic Energy You saw that increasing the drop height increased the work done on the cup (which means the energy increased) What does changing the drop height do to the motion of the marble? So increasing the drop height increased the speed or velocity of the marble The work done on the cup is a way to think about the kinetic energy of the marbles

Repeat the procedure for one and two marbles but only for 30 cm and 7.5 cm – But this time remove the cup and put a piece of tape one meter away from the end of the ramp Measure the time it takes a marble to travel from the bottom of the ramp to the tape 1 meter

Use the time measurements To calculate velocity – v = distance = d/t time So if a marble rolls 1 meter in 5 seconds the velocity will be v = 1m/5s or v = 0.2 m/s

What happened… When you increased the drop height from 7.5 to 30 cm – What happened to the distance the cup moved? – What happened to the speed of the marble? Drop HeightCup moved (cm) (energy of marble) Speed (m/s) 7.5 cmXx 30 cm4X2x

Calculating Kinetic Energy We can actually calculate the kinetic energy! KE = ½ mv 2 m = mass in kilograms v = velocity in meters per second (m/s) We know the mass = 5.5 grams 5.5 g = kg So the kinetic energy of the marbles we tested was = ½ v 2