# konneroakes' Blog

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Roofing

## How to carry groceries

Every time I get groceries with my mom I try to bring all of them in the house at once. She typically says, "You should take more trips!" But physics is on my side. It requires more work to bring in several loads of groceries opposed to just one big load. If work is a force x a distance than one big trip will require the least amount of work. To make one big load requires me to move the huge load of groceries, and myself once from the car into my house and into the kitchen. Simply taking two tri

## Physics of throwing a discus

Their is a lot of physics in throwing a discus. A throwers body must move in a certain way to provide the maximum power to throw the disc. Throwers must spin to create centripetal acceleration and land in a way to wind up their hips. The hips act like a spring and the thrower pivots his/hip as fast as possible to launch the disc. Not only is power a factor but releasing a disc correctly is extremely important. The disc should be released at a 45 degree angle from the thrower. The disc itself mus

## How to be good at Drag Racing

Typically before a drag race the drivers will spin their tires really fast. This converts Kinetic energy (the movement of the tires) into thermal energy from the friction the ground provides. The tire then is very hot and sticks to the racetrack very well. When the light goes green the friction between the ground and the tire is much greater than if the tire was cold because the hot tire expands and pushes into small bumps In the asphalt much more. The car can launch much easier and convert the

## Cars made "weaker" in certain areas for safety

Back in the 1950's cars weren't made with crumple zones. Cars were made with very simple, straight sheets of steel that weren't made to bend when they crash. So in certain situations ,like fender benders, these cars are great because the fenders won't bend and will break parts on the other car. However if someone smashes into a telephone pole the car won't provide a great enough impulse for a good chance of survival. In the 1970's the growing concern for car safety led to car companies creating

## Monsters Inc. teaches kids Physics

I had to babysit my younger sister and she wanted to watch Monsters Inc. Although the movie's plot may not be the most realistic the physics concepts of the movie are realistic. If you haven't seen the movie children's screams and laughs power doors so when a child laughs they can open up a door to the human universe. A scene included the main characters, Mike and Sully, having their door fall from very high up. Sully is a very big monster and Mike is very small but they both fall at the same sp

## Why is it easier to open a pickle jar after running it under hot water?

Opening a tightly sealed pickle-jar can be tricky. There is a logical Physics explanation why running it under hot water can make it easier to open. If we assume it is your average glass pickle-jar with a metal top than heating up the jar will loosen the lid because the metal conducts more heat than the glass. This means the metal will expand before the glass gets the chance to expand the same distance, so as the metal expands the Force required to open the jar decreases. This may seem confusing

## The physics of stubbing your toe

Walking into a wall or a doorway and hitting your toe can be very painful. Their is a logical explanation for this pain. Walking requires a lot of energy because to walk you must produce friction with the ground with your legs. People swing their legs forward to take another step. When you swing your leg out into a wall and hit your toe, all of the force from the swing goes directly into your toe. It isn't the force that you supply that hurts your toe but the force the wall exerts back on you wh

## The Physics of sitting

When sitting in a chair a lot of forces are acting on each other. As I sit in a chair the force of gravity multiplied by my mass determines the force acting on the chair. Although it seems I am only supplying a force onto the chair, the chair is supplying an equal, opposite force up on me to keep me from moving down. If the chair was not supplying a normal force back on me I would accelerate downwards to the ground at 9.81 m/s. The chair I am sitting in also supplies a force on the ground. The g

## My dog on his chain

One time last year the anchor for the chain I attach my dog's chain to broke. To keep my dog from running away we attached the chain to a heavy metal ladder. What we didn't consider was my dog weighs upward of 100 lbs. My dog produced a large enough force to drag the heavy ladder across the ground. Friction made it difficult for my dog to drag the ladder because to initiate the movement of the ladder my dog had to break the force of static friction to move the ladder. As my dog kept moving the f

## Football

I was playing catch with a football on the football field and thought about the best angle to throw football. I found that when I threw the football at 45 degrees it travelled the farthest distance. Whenever an object is in the air, neglecting air resistance, the object will fall towards the earth at 9.81 m/s. Launching an object straight up in the air will keep it in the air for the longest time but it wont travel any horizontal distance. Also throwing the ball at 0 degrees above the horizonta

## Roofing

While I was roofing over the summer with my dad he would put bundles of shingles up on the asphalt roof. The angle of the roof was about 30 degrees. Friction was keeping the bundles of shingles on the roof. However if they were touched just a little they would slide down the roof a little. If I create a free-body diagram of the bundle of shingles on the roof I find that FNet=mg so Ff- mgsin<=0 so Friction=mg< and the normal force is FN= mgcos<. To find friction coeff. of friction= mgsin

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