Unit 5 Astrophysics
- Created by: megan
- Created on: 24-03-13 17:14
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- Astrophysics and Cosmology
- The attraction of the stars
- Every particle with mass attracts every other particle with mass.
- The big bang spread tiny particles across space, the particles move towards each other and clump together
- This effect is more pronounced for particles nearer to each other.
- a particle that has a mass will feel a force when it is in a gravitational field
- The force that a body will feel is the strength of the gravitational field multiplied by the amount of mass
- f=mg=ma.
- The force that a body will feel is the strength of the gravitational field multiplied by the amount of mass
- a massie particle will generate a radial gravitational field around itself
- Gravity is always attractive
- The gravitational force between two masses which are separated by a distance is F= Gm1m2/r^2
- G Is the gravitational constant = 6.67x10^-11
- Gravitation field strength
- The strength of the field decreases with increasing distance from the mass causing it.
- The field strength is independent of the object being acted upon.
- g= -GM/r^2
- Electric and gravitational fields
- They are similar because they are both types of field that are radial from a point.
- They differ because gravitational field is always attractive and an electric field is not. Electric fields are also stronger than gravitational fields
- Stella Properties
- The only information we receive from the stars is the electromagnetic radiation from them
- This tells us their temperature, chemical composition, speed of movement, age and size.
- The only information we receive from the stars is the electromagnetic radiation from them
- The stefan botlzmann law
- Luminosity is the precise measure used to classify the brightness of stars.
- Is is the rate at which energy of all types is radiated by an object in all directions
- Luminosity depends on size and temperature.
- A perfect radiator is a black body and will give off energy across the entire electromagnetic spectrum
- The stefan boltzmann law tells us that the power output from a black body is proportional to its surface area and the forth power of its temperature.
- L= oT^4 4Pi r^2
- o= 5.67x10^-8
- L= oT^4 4Pi r^2
- Luminosity is the precise measure used to classify the brightness of stars.
- Wiens law
- To calculate luminosity we need to know the temperature of the star.
- As the temperature increases, a star emits more energy.
- The wavelength of the peak wavelength gets shorted as temperature rises
- Max Wavelength x Temperature = 2.89x 10^-3
- The attraction of the stars
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