Prelim Physics Thread (7 Viewers)

[ThreeSciences]

Question:
A driver of mass 75kg travelling in a 1200 kg sedan collides with a stationary police car with total mass of 1500 kg. The tangled wreck moves off after the collision at 8 ms^-1. Assuming negligible frictional force on both vehicles: Calculate the impulse on the police car due to the collision.

Just need confirmation cause I'm not 100% sure about the answer at the back
thankyou very much

Impulse = Ft = m • ∆v
= (1500kg) • (8m/s - 0m/s)
= 12000kgm/s

 

[drsabz101]

Why is a wooden chair , which consists of many electrons and protons, not a charged object itself?

 

[Shuuya]

Why is a wooden chair , which consists of many electrons and protons, not a charged object itself?

An object is not charged unless there is an imbalance of protons/electrons. So the chair wouldn't be charged because there should be equal numbers of protons and electrons, meaning that the charge is neutral.

 

[Green Yoda]

An object is not charged unless there is an imbalance of protons/electrons. So the chair wouldn't be charged because there should be equal numbers of protons and electrons, meaning that the charge is neutral.

Plus it is a great insulator
so >Resistance and thus opposes the free flow of electrons to become charged
also It doesn't have a crystal lattice structure like metals so no de-localised electrons and thus less chance for the electrons to move in and out so less chance of an imbalance of protons and electrons and thus less chance for the particle to be charged.

 

[eyeseeyou]

An object is not charged unless there is an imbalance of protons/electrons. So the chair wouldn't be charged because there should be equal numbers of protons and electrons, meaning that the charge is neutral.

I'm pree impressd you remebered this Shuuya

 

[Green Yoda]

I'm pree impressd you remebered this Shuuya

isnt it like common knowledge for science students?

 

[eyeseeyou]

isnt it like common knowledge for science students?

Depends on the individual

 

[eyeseeyou]

Need help with cosmic engine questions:

1.What theory does the red-shift support?
2. Calculate the velocity of recession of a distant galaxy at 12.5 Mpc from us
3. Assess one of the models of the universe developed from the time of Aristotle to the time Newton to identify the limitations placed on the development of the model by the technology available at the time
4. Outline briefly how the accretion of galaxies occurred.

 

[eyeseeyou]

Need help with cosmic engine questions:

1.What theory does the red-shift support?
2. Calculate the velocity of recession of a distant galaxy at 12.5 Mpc from us
3. Assess one of the models of the universe developed from the time of Aristotle to the time Newton to identify the limitations placed on the development of the model by the technology available at the time
4. Outline briefly how the accretion of galaxies occurred.

Also need help with further maths cosmic engine questions:

1. a. Calculate kepler's constant for the following planets
b. What conclusion can you draw?

Info here is: Planet is earth. Period (s) is 3.156x10^7s and average distance (m) is 1.4957x 10^11
Planet is Mars. Period (s) is 5.93x10^7s and average distance (m) is 2.278x10^11

2. Calculate the average radius of Saturn's orbit given the following information:
-period of Saturn's orbit=29.45 yeard
-period of Earth's orbit=1 year
-radius of earth's orbit-1.5x10^11m

 

[InteGrand]

Also need help with further maths cosmic engine questions:

1. a. Calculate kepler's constant for the following planets
b. What conclusion can you draw?

Info here is: Planet is earth. Period (s) is 3.156x10^7s and average distance (m) is 1.4957x 10^11
Planet is Mars. Period (s) is 5.93x10^7s and average distance (m) is 2.278x10^11

2. Calculate the average radius of Saturn's orbit given the following information:
-period of Saturn's orbit=29.45 yeard
-period of Earth's orbit=1 year
-radius of earth's orbit-1.5x10^11m

Have you learnt Kepler's Third Law?

 

[eyeseeyou]

Have you learnt Kepler's Third Law?

Yeah but I struggle with da maffs

 

[InteGrand]

Yeah but I struggle with da maffs

The maths of the Third Law is pretty simple to apply. The laws' derivations are pretty interesting mathematically speaking, and how they can be derived from Newton's Law of Gravitation / conservation of angular momentum.

 

[eyeseeyou]

The maths of the Third Law is pretty simple to apply. The laws' derivations are pretty interesting mathematically speaking, and how they can be derived from Newton's Law of Gravitation / conservation of angular momentum.

I'm talking about the equation I posted up

Also could you help me with my other questions (which I posted up earlier today)

Thanks

 

[eyeseeyou]

Need help with cosmic engine questions:

1.What theory does the red-shift support?
2. Calculate the velocity of recession of a distant galaxy at 12.5 Mpc from us
3. Assess one of the models of the universe developed from the time of Aristotle to the time Newton to identify the limitations placed on the development of the model by the technology available at the time
4. Outline briefly how the accretion of galaxies occurred.

Also need help with further maths cosmic engine questions:

1. a. Calculate kepler's constant for the following planets
b. What conclusion can you draw?

Info here is: Planet is earth. Period (s) is 3.156x10^7s and average distance (m) is 1.4957x 10^11
Planet is Mars. Period (s) is 5.93x10^7s and average distance (m) is 2.278x10^11

2. Calculate the average radius of Saturn's orbit given the following information:
-period of Saturn's orbit=29.45 yeard
-period of Earth's orbit=1 year
-radius of earth's orbit-1.5x10^11m

These 2 question Integrand

 

[ThreeSciences]

Need help with cosmic engine questions:

1.What theory does the red-shift support?
2. Calculate the velocity of recession of a distant galaxy at 12.5 Mpc from us
3. Assess one of the models of the universe developed from the time of Aristotle to the time Newton to identify the limitations placed on the development of the model by the technology available at the time
4. Outline briefly how the accretion of galaxies occurred.

For the first one it's the theory that the universe is expanding. As the Universe expands in all directions, the light being emitted from things such as stars becomes red shifted as the distance between the observer and the light source increases (thus decreasing the frequency).

 

[eyeseeyou]

BUMP someone please answer my Q's from the last page or so

 

[turntaker]

Bump someone answer his q

 

[1008]

Also need help with further maths cosmic engine questions:

1. a. Calculate kepler's constant for the following planets
b. What conclusion can you draw?

Info here is: Planet is earth. Period (s) is 3.156x10^7s and average distance (m) is 1.4957x 10^11
Planet is Mars. Period (s) is 5.93x10^7s and average distance (m) is 2.278x10^11

2. Calculate the average radius of Saturn's orbit given the following information:
-period of Saturn's orbit=29.45 yeard
-period of Earth's orbit=1 year
-radius of earth's orbit-1.5x10^11m

do you mean these?

 

[eyeseeyou]

do you mean these?

They're cosmic engine maths questions

 

[1008]

They're cosmic engine maths questions

Which ones lol?