yellow light

Is the yellow light timed correctly?

A car goes 30 mph will it have enough time for it to cross the yellow light when it reaches the start of the intersection at Lamar and Rundberg Ln.

The length across the street from the stopping lane to the other side of the yellow light:  87.75 ft. or 1/60miles

Aprox. Time it takes from the light to change from yellow to red: 5 seconds

Average speed that the car goes: 30mph or 1/120 mile per second

Form the start of the stopping line you are going at 30mph you take 2 seconds to cross the road enough time.

Calculations: 1/60 x 2 seconds = 1/120

With a constant speed of 30mph you can pass the yellow light form about 1/24 mile away or 220 ft in 5 seconds.

Calculations:

1/120 x 5 = 1/24

If a car goes faster than 30mph then it means that they can be farther than 1/24 of a mile and cover a greater distance to reach the other side of the road.

If you are farther away from 220ft you will have to accelerate in order to pass the yellow light. 

If you are in the middle of the street you have to go on to the other side even if the yellow turn red, you don’t want to cause an accident.

Diagram coming soon 

Galileo's Lab

Background/History

Galileo Galilei an astronomer and physicist was born on February 15, 1564 in Pisa, Italy famous for his physics and astronomical contribution. He was the first to use a refracting telescope and discovered the moons of the Jupiter and the phases of Venus. He also stated the “law of falling bodies which is that a vacuum of all bodies, regardless of their weight, shape, or specific gravity, are uniformly accelerated in exactly the same way, and that the distance fallen is proportional to the square of the elapsed time” (i.e. m/s^2) (On Motion).

Hypothesis

In this experiment we are going to prove Galileo’s experiment in showing that a given distance was proportional to the square of the time. 

Materials

A piece of aluminum channel used as a ramp

Steel ball

Stopwatch

Book

Meter stick

Procedures

1. Place the ramp on top of the book to have a inclined plane.

2.Measure and mark it in 0.2 m, 0.4m, 0.5m, 0.6m and 0.8m.

3. Drop the metal ball for 3 trails each distance

4. Record in a table

5. Calculate the average time

6. Create a graph

 Data

Conclusion

Galileo’s theory was indeed correct as can be seen in the graph and table above; the distance is proportional to time squared. The results of the table and graph are not entirely perfect, because of its difficult to stop the stopwatch exactly when the ball hit the ground, seen in the 0.4m and 0.5m times.  To have a more accurate measurement we could have use a motion detector and connected to a stopwatch to have a closer measurement of the times. 

Sources

Mr. Wright’s lab sheet

http://galileo.rice.edu/sci/theories/on_motion.html  

Velocity vs Speed

Average Velocity = Final Displacement

Total Time

Average Speed= Total distance traveled
                                    Total Time