Energy

Energy is the ability to do work.
Energy is needed in order to do work.

Heat energy:)

HEAT INDUCED ROTATING LAMP SHADE

When the bulb is lit, it will generate heat. The heat generated will warm the air surrounding the bulb, causing it to rise. The rising warm air will travel upwardly inside the conical shade with the air escaping out the slits provided in the surface of the shade. The warm air escaping through the slits will apply a force to the unidirectional vanes which will cause the shade to rotate.

Reference: http://www.freepatentsonline.com/5491616.html

In shorter words, when the bulb lits up, heat and other forms of energy is produced. The moving hot air surrounding the slits will rise and will apply a force on the slits, causing the vanes to rotate.

Hydroelectric dams

The water in the reservoir is considered stored energy. When the gates open, the water flowing through the penstock becomes kinetic energy because it's in motion. The amount of electricity that is generated is determined by several factors. Two of those factors are the volume of water flow and the amount of hydraulic head. The head refers to the distance between the water surface and the turbines. As the head and flow increase, so does the electricity generated. The head is usually dependent upon the amount of water in the reservoir.

Reference: http://science.howstuffworks.com/hydropower-plant1.htm

The principle of moments.

The principle of moments states: when a body is in equilibrium, the sum of all clockwise movements about a pivot is equal to the sum of all anti-clockwise movements about the same pivot.

Deadweight

• An oppressive burden or difficulty.
• The unrelieved weight of a heavy, motionless mass.
• Deadweight tonnage is an expression of a ship's carrying capacity, including the weight of the crew, passengers, cargo, fuel, ballast, drinking water and stores
• The extra weight on a machine part that lowers its performance when not in use. For example, the main engine on a rocket becomes dead weight when the propellant is used up. For this reason, multi-stages rockets eject engines after they have been utilised to reduce the dead weight. However, the later stages of the rocket are initially deadweight in the early stages of launch.ater, and stores.

Reference: http://en.wikipedia.org/wiki/Deadweight

http://www.youtube.com/watch?v=esm4s9iK_Gs

Click link to see video.( The one we saw in class)

I think the plane crash was due to the fact that the plane was overloaded. The crew estimated the the mass of each passenger and added the total mass of the luggages/bags and concluded that the total mass of the load had not reached its capacity. Unfortunately, his estimated mass of each passenher was lesser than the actual mass, plus,the crew's calculation of the total mass of the bags/luggages was not accurate. Hence, the plane was flying at a abnormal angle as back of the plane,which contains all the bags/luggages, was too heavy and became unbalanced. The pilot tried to bring the nose of the plane lower but to no avail. The plane eventually crash and exploded because of ignited full tank fuel in the plane.

Stilletto Heels

Effects of wearing high heels/stilletto heels.(Bad)

1. A high heeled shoe forces the posture into an unnatural position that significantly stresses the joints. The spine, which in flat shoes is reasonably straight, forms more of an ‘S’ shape with the chest and lower back pushing forward and the hips pushed back. The height of the heel also changes the amount of weight on the forefoot. A 1-inch heel will increase the pressure by 22%; a 2-inch heel by 57%; and a 3-inch heel by 76%. This increased pressure puts the forefoot at risk for injuries such as stress fractures, bunions, and hammertoes.

2. Knee pain is common when high heels are involved. The heel height causes increased strain on the knee joint and associated tendons. The quadriceps muscle group in the front of the thigh works harder, increasing pressure on the kneecap by up to 26%. This can ultimately increase the incidence of osteoarthritis of the knee and quadriceps tendinitis.

3. Because of the constant elevation of the heel, contraction and shortening of the calf muscles and Achilles tendon may occur. Habitual wearing of extremely high heels can cause a woman to be unable to tolerate a flat shoe. On occasion, this can even require surgery to lengthen the Achilles tendon. Most often, however, this will increase the chances of Achilles tendinitis or shin splints.

4. The changes in posture and overall imbalance will lead to instability when walking and a resulting risk of ankle sprains. High heels, especially stilettos, will lead to instability and a major increase in ankle sprains result. An ankle sprain is caused from the twisting of the ankle and results in a tear of the ligaments that connect the foot and leg bones and stabilize the ankle. When the heel is balancing on a narrow stiletto heel, if the heel shifts outward slightly a sudden twist may occur to sprain these ligaments. Swelling, bruising and pain will result. At worst, it is possible for the ankle to fracture, a ligament can pull a piece of bone off, or even a bone in the foot can break due to the pull of a tendon.

5. High heels are enjoyed by most women because they are "cute." They are narrow and are contoured to make the foot look slender. The tight fit of many heels will force the toes to conform to its shape. The added pressure on the toes can exacerbate bunions and hammertoes. The pressure of the shoe itself can cause corns to form. Furthermore. The compression of the metatarsal bones can cause pressure on the nerves that run between them. This pressure can cause a growth and inflammation of the nerve known as a Morton’s neuroma. Remember, a shoe is meant to fit the foot, not squeeze it relentlessly.

Reference: http://footsolutionsonline.ning.com/profiles/blogs/five-risks-of-wearing-high

How does the gravitational pull on the moon affects the high and low tides on earth?

The gravitational attraction that the Moon exerts on Earth is the major cause of tides in the sea; the Sun has a lesser tidal influence. If the Earth possessed a global ocean of uniform depth, the Moon would act to deform both the solid earth (by a small amount) and ocean in the shape of an ellipsoid with high points directly beneath the Moon and on the opposite side of the Earth. However, as a result of the irregular coastline and varying ocean depths, this idealization is only partially realized. While the tidal flow period is generally synchronized to the Moon's orbit around Earth, its phase can vary. In some places on Earth there is only one high tide per day, though this is somewhat rare.

Reference: http://en.wikipedia.org/wiki/Orbit_of_the_Moon