Have you ever wondered how a vending machine "knows" that you have put in the correct amount of change to purchase a snack or a drink? These machines use coin detectors that determine the mass and the size of the coins deposited. In other words, they analyze the density of the coins. United States coinage is minted within very narrow specifications, so the density of each type of coin is always the same. The coin detectors compare the coins inserted to the preset standards to determine if the correct combination of coins has been deposited. In this lesson, you too will determine the density of various coins. This animation will allow you to find the density of a penny, a nickel, and a quarter.

Make a hypothesis in which you suggest which coin will have the highest density and which will have the lowest density. A model hypothesis might be: "If the (fill in the name of a coin) has a greater density than the and , then it will have a greater mass to volume ratio. If the (fill in the name of a coin) has a lower density than the and , then it will have a lower mass to volume ratio.

Remember to record your data and observations in the data sheet so that you can use them to present your findings.
Present Your Findings
Write a one or two summary paragraph discussing this experiment and the results. Use the following questions and topics to help guide the content of your paragraph.

According to your data, was your hypothesis correct? (Be sure to refer to your data when answering this question.)
Summarize any difficulties or problems you had in performing the experiment that might have affected the results. Describe how you might change the procedure to avoid these problems.
List at least two real world examples that apply the findings of this experiment. (Hint: An example of this type was given in the introduction to this project.)

Follow these directions and answer the questions. 1. shine a pencil-thin beam of light on a mirror perpendicular to its surface. (if you don't have a laser light as suggested in the video, you can make a narrow beam from a flashlight by making a cone from black construction paper and taping it over the face of the flashlight.) how does the light reflect? how does the relationship of incident to reflected ray relate to the reflection of water waves moving perpendicular to a barrier? 2. shine a pencil-thin beam of light on a mirror standing on a sheet of paper on the table (or floor) so that you can mark the incident ray and reflected ray. (you can support the mirror from the back by taping it to a wooden block.) 3. mark a line on the paper representing the reflective surface. (the reflective surface of a mirror is usually the back edge.) 4. draw a dashed line perpendicular to the mirror surface at a point where the incident and reflected ray meet. this perpendicular is called a normal to the surface. 5. measure the angles between the rays and the normal. the angle of incidence is the angle formed by the incident ray and the normal to the surface. the angle formed by the reflected ray and normal is called the angle of reflection (r). what is the angle of incidence? what is the angle of reflection? 6. repeat for several different angles. (see report sheet for details.) what appears to be the relationship between the angle of incidence and angle of reflection? in science 1204, what was the relationship for these two angles made by the reflection of waves in a ripple tank? 7. roll a ball bearing so that it hits a fixed, hard surface (a metal plate) at several angles (including head-on). observe the way in which the ball bearing reflects. what generalization can you make about how a ball bearing reflects from a wall? have you proved that light can only behave like a wave?

There are two-speed cameras, one in an are where the speed limit is 30 km/h and another where the speed limit is 50 km/h. in which will there be a smaller time interval between the photographs? explain your answer.

You want to lose weight and have been trying to decide which type of fad diet is best for you. you ask your doctor, who responds that a. fad diets are a temporary fix but generally don't have any side effects b. fad diets can be used several times a year to maintain a healthy weight c. fad diets can be risky for your health and, in the long run, do not work d. fad diets should never be used one right after the other; there should be a break between them select the best answer from the choices provided. a b c d