Pulleys in Action

Pulleys are an excellent example of how our work efforts can be increased. We’ve learned that the 6 common simple machines are the pulley, lever, wheel and axle, screw, inclined plane and a wedge. Through the generous help of a Skyline PTSA grant (HUGE thanks to Skyline’s PTSA!), we had Christian, a local engineer in Salt Lake City, propose the problem of how to get our teacher up to the rim of a basketball hoop and dunk a ball, using the 7th graders’ minds and muscles. We considered time, money, science and safety to make our decisions and to create a plan. We learned that each pulley increased our effort, or provided more mechanical advantage. With one pulley, the force we used to lift our teacher wasn’t increased, but it changed the direction of our force. To lift our teacher, we’d need to lift up, but now we could pull down. Because our teacher weighs 215 lbs., we couldn’t lift him. When we set up a two pulley system, our teacher’s weight was divided in half (divided by 2) but only Christian could lift him because we don’t weigh more than 107.5 lbs. so even if we jumped into the air to lift our teacher, we couldn’t produce enough force. With 3 fixed pulleys we started to have success and our teacher’s weight was now divided by 3 and we only needed to pull with 71.7 lbs. pounds of force. Success!

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We had fun using the concept and dividing our weight by 2 and 3, to see how much force our classmates needed to use to lift us!

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The 8th grade Physical Science class added to the concepts of learning by figuring out the force distance tradeoff. Simple machines don’t do work, they just make work easier, or more efficient, for us. To lift a load a certain distance, that distance must be multiplied by the number of pulleys and moved by whatever force is lifting the load. For example, if we lift our 215 lb. teacher 4.25 feet to the rim of an official NBA basketball hoop (keeping in mind that he’s 6 feet tall and where the harness connects to the pulleys is 9 inches from his head) using a 3 pulley system;

distance to move the load  x   # of pulleys = distance whatever is applying the force must move

4.25 ft.          x       3       = 12.75 ft. the puller must move in order to lift our teacher 4.25 ft.

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Even our teacher’s wife joined in on the fun! 20140427-162903.jpg

 

Practice:

Jarrod weighs 250 lbs. and would like to be lifted by a pulley system into the back of a pickup truck. If the top of the tailgate is 48 inches high;

1. How much force is needed to lift Jarrod with a 3 pulley system?

2. If a 4 pulley system is set up, how far would the person pulling the rope have to move?

 

A cubic foot of coal weighs 84 lbs. If this load of coal needs to be lifted into a truck at a height of 5 feet,

3. How much force is needed to lift the coal with a 3 pulley system?

4. If a 4 pulley system is set up, how far would the person pulling the rope have to move?

Science Fair 2014

After long days, weeks and even months of hard work, it was time for the Utah School for the Deaf’s (USDB) students to compete in the annual Salt Lake Valley Science and Engineering Fair (SLVSEF)! On March 19th, four brilliant 5th and 6th grade Deaf students competed in 4 different categories (biology, biochemistry, physics and human behavior). Each student described their project to at least 4 judges and everyone learned a lot! This was the first year for USDB to be in the regional science fair, so it was an exciting day!20140427-155034.jpg

On March 20th, 15 7th-12th grade students competed in SLVSEF and also did a wonderful job. They presented their projects to at least 5 judges each and experienced the University of Utah campus. The USDB students’ projects ranged from rockets to DNA extraction, animal bio-magnetism to cold tolerance in mammals.20140427-155109.jpg20140427-155132.jpg

 

 

 

To round out the week, on Friday, March 21st, USDB had the honor of attending its first SLVSEF awards ceremony! In addition to hair-raising electromagnetic and static electricity experiments, hundreds of students, ranging from 5th-12th grade, poured into Taylorsville High School’s auditorium to share their passion of science with one another and to continue to improve their work!

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USDB had a great first year! Four students received a personal invitation to a Science Summer camp, due to their excellence in their competition category. Senait won a prestigious award from the local 4H chapter for her outstanding work with her culinary arts project. Similarly, Rhett and Meseret won a Technology and Application award from 4H for their work with biomagnetism in grazing cattle. Alexah, who worked with DNA extraction and procurement procedures, won third in the molecular biology category!

Finally, USDB was recognized as “an overly enthusiastic group of kids who seem curious and excited to learn” by the University of Utah’s Outreach program and we will begin a partnership program with them in the Fall of 2014!

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Adventures in Speed calculations!

In the science of motion (kinematics) speed is defined as the rate of velocity in which an object changes it’s position. To calculate average speed, we use the simple equation:

Speed= distance / time

Speed is frequently measured in meters per second in science, but various countries which are finely attuned to their automobiles and have an affinity for speed often use miles or kilometers per hour.

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In those pictures, our 110cm long school tables provided a perfect pitch for various school items and materials from the science lab to roll down.

Using handheld stopwatches, we timed how long the items took to roll/slide down the table.

i.e. Alexis slid a pen down the 110cm table and it reached the end at an average time of 2.38 secs after 15 trials. Alexis then had the proper components to calculate the pen’s speed. He first converted 110cm to 1.1 meters, then divided it by the average time (2.38 secs).

1.1 m / 2.38 sec = .46 m/s

Practice:
What is the speed of Tim’s ball rolling down a 140 cm table with an average time of 3.12 secs?

Greyhound dogs can run 291.6 meters in 15 secs. What is their speed in meters per second?

*Husain Bolt, the fastest man on the planet, can run 1490.4 meters in 2 minutes, what is his speed? (Remember, it needs to be in m/s)

Arches National Park

Nestled just outside of Moab, UT, Arches National Park proudly boasts that 1 million visitors viewed it’s iconic, sandstone arches, which merge desert lovers with communities from afar, and never ceases to amaze.

For those who can’t easily access Arches National Park, this video will hopefully provide some insight into some of the more well-known arches, a bit of geology, and panoramic views of some of the most beautiful geologic features of North America.