section 1: Work and Power
vocabulary
1) Work: the transfer of energy to an object by using a force that causes the object to move in the direction of the force
2) Joule: the unit used to express energy; equivalent to the amount of work done by a force of 1 N acting through a distance of 1 m in the direction of the force (symbol, J)
3) Power: the rate at which work is done or energy is transferred
4) Watt: the unit used to express power; equivalent to joules per second (symbol, W)
2) Joule: the unit used to express energy; equivalent to the amount of work done by a force of 1 N acting through a distance of 1 m in the direction of the force (symbol, J)
3) Power: the rate at which work is done or energy is transferred
4) Watt: the unit used to express power; equivalent to joules per second (symbol, W)
summary
This section discussed work and power. Work (vocabulary word 1) is the transfer of energy to an object by using a force that causes the object to move in the direction of the force. One way to tell if work has been done on an object is if the object now has kinetic energy, which may cause the object to move. However, force and work are not always constant. Just because you exert force on an object, that doesn't mean that work is being done. For example, if you push a boulder you are applying force to the boulder, however wok is not being done on the boulder because the boulder is not moving. Also, work is not being done on an object unless the object moves in the same direction that the force is applied. For example, picking up a pair of dumbbells is work because you are applying upward force to the object and the object is moving upward, however, if you begin to walk with the dumbbells you are not doing work on the object because you are still applying upward force but the dumbbells are moving forward.
Next is how much work over different distances. For example, if you are walking up the less steep side of a mountain and someone else is climbing up the steep side of the mountain you both would end up doing the same amount of overall work. This is because they have a shorter distance to the top so they are doing a large amount of work in a short amount of time, but you are doing a much smaller amount of work over a much longer period of time. In the end it all balances out to about the same amount of overall work. Work can be calculated with the following equation, W= F x d (Work equals Force applied times the distance). The units used to express work are the newton-meter (N x m) or the joule (vocabulary word 2; symbol, J). The joule is also a unit used to express energy.
Lastly is power. Power (vocabulary word 3) the rate at which work is done or energy is transferred. Power can be calculated with the following equation, P= W/t (Power equals Work done divided by time). Power is expressed in joules per second (J/s) also called the watt (vocabulary word 4). When more work is done in a given amount of time, the power output is greater. The power output is also greater when the time it takes to do a certain amount of work is decreased. Certain machines can also be used to help increase power, for example, it would be better to use an electric sander than it would to use sand paper to sand wood because the electric sander is more powerful. The same also goes for using a hair dryer as opposed to using a fan to dry your hair. The hair dryer is more powerful than the fan.
Next is how much work over different distances. For example, if you are walking up the less steep side of a mountain and someone else is climbing up the steep side of the mountain you both would end up doing the same amount of overall work. This is because they have a shorter distance to the top so they are doing a large amount of work in a short amount of time, but you are doing a much smaller amount of work over a much longer period of time. In the end it all balances out to about the same amount of overall work. Work can be calculated with the following equation, W= F x d (Work equals Force applied times the distance). The units used to express work are the newton-meter (N x m) or the joule (vocabulary word 2; symbol, J). The joule is also a unit used to express energy.
Lastly is power. Power (vocabulary word 3) the rate at which work is done or energy is transferred. Power can be calculated with the following equation, P= W/t (Power equals Work done divided by time). Power is expressed in joules per second (J/s) also called the watt (vocabulary word 4). When more work is done in a given amount of time, the power output is greater. The power output is also greater when the time it takes to do a certain amount of work is decreased. Certain machines can also be used to help increase power, for example, it would be better to use an electric sander than it would to use sand paper to sand wood because the electric sander is more powerful. The same also goes for using a hair dryer as opposed to using a fan to dry your hair. The hair dryer is more powerful than the fan.