I knew I shouldnt have taken gr. 11 physics...

[Death]

Can someone please help me with these physics questions? Our teacher told us it was background imformation that we should already know but I dont recall doing any of this last year.

Given θ = 30 degrees Solve for: sin θ, cos θ, tan θ
How would i do this? Just substitute 30 for θ?

Given tan θ = 1.2 Solve for θ, sin θ, cos θ

Given a = delta v/delta t Solve for v2, and delta t

Given displacement = v1*delta t + 1/2a(delta t)^2 solve for v1, a, delta t

PLEASE HELP!!

 

[zrky]

Can someone please help me with these physics questions? Our teacher told us it was background imformation that we should already know but I dont recall doing any of this last year.

Given θ = 30 degrees Solve for: sin θ, cos θ, tan θ
How would i do this? Just substitute 30 for θ?

Given tan θ = 1.2 Solve for θ, sin θ, cos θ

Given a = delta v/delta t Solve for v2, and delta t

Given displacement = v1*delta t + 1/2a(delta t)^2 solve for v1, a, delta t

PLEASE HELP!!

this is the reason why i don't look forward to taking physics

Spoiler

it never works either

but honestly I really don't know how to help, but my best guess is to substitute

 

[GoldShadow]

Hm... this is pretty basic stuff. Have you taken precalc yet? Nonetheless:

Can someone please help me with these physics questions? Our teacher told us it was background imformation that we should already know but I dont recall doing any of this last year.

Given θ = 30 degrees Solve for: sin θ, cos θ, tan θ
How would i do this? Just substitute 30 for θ?

Yes. You can plug it into a calculator. Alternatively, if you know about/know how to use the unit circle, you can just use that to determine the values.

Given tan θ = 1.2 Solve for θ, sin θ, cos θ

Same as above, basically. To determine what θ is, you need to use the inverse tangent function of a calculator (tan^-1), also called arctan. Then use the same method as the first question to solve sin and cos.

Given a = delta v/delta t Solve for v2, and delta t

Remember that Δ (delta) means change in, or final minus initial.
In other words, another way of writing the equation is:

a=(v2-v1)/Δt

Just use some basic algebra to solve for v2.

You can also just use simple algebra to solve for Δt in the original equation a=Δv/Δt

Given displacement = v1*delta t + 1/2a(delta t)^2 solve for v1, a, delta t

PLEASE HELP!!

This is also just simple algebra. v1 and a are easy to solve for. Δt might give you some trouble because it shows up in two terms; you'll have to use the quadratic formula to solve for Δt.

 

[Xsyven]

Goldshadow to the rescue!

 

[Livvers]

I miss physics class. Physics is sexy.

I remember nothing about equations, though, so I guess I'm having fun being useless =D

 

[Death]

So, Goldhsadow, for the first one, I just plug into the calculator sin 30 degrees? and the same for cos and tan? And then what?

Fr the second one, I just arctan 1.2?? This gives me around 50.19. And then just do sinANSWER??

Okay the third one I understand and the fourth one i need to use x = -b + minus square root of b2 - 4 ac divided by 2a?

 

[Death]

And since you seem to know your physics could you help me out with one more question?

The takeoff speed of a B747 is about 290km/h.
a) Estimate the acceleration of a fully loaded B747. Can ou justify your estimate.
b) Use you estimate from a) to calculate how long a runway you would have to build for a B747.

This is what I have so far.

a) a = Δv/Δt
a = 290km/h / 35 s (I just made up a number approximately how long it takes for takeoff)
a = 8.29 --> 8.3 km/h/s or about 2.3 m/s^2

b) Δd = v1Δt + 1/2a(Δt)^2
Δd = 0 + 1/2((2.3m/s^2)(35s)^2
Δd = 1.15m/s^2 (1225s^2)
Δd = 1408.75 m

Would this be anaccurate response? Thank you very much !!

 

[Sad Panda323]

Oh god, and I thought my 10th grade physics class was hard.

 

[Rusty Shacklefurd]

Δt might give you some trouble because it shows up in two terms; you'll have to use the quadratic formula to solve for Δt.

Screw that! Whenever I have to use that formula to solve for time, I just use a different formula to solve for an unnecessary value and then use it to find time. I HATE THE QUADRATIC FORMULA AND AVOID IT WHENEVER POSSIBLE!!!

 

[OmegaXXII]

"these" equations make my brain hurt, though Algebraic equations have always been my greatest academic weakness. *shouldn't have revealed this*

 

[M.K]

I learned sin, cosin, and tangent in Geometry 0.o Is Physics hard? I'm debating whether or not to take it....

 

[Grunt]

I learned sin, cosin, and tangent in Geometry 0.o Is Physics hard? I'm debating whether or not to take it....

My physics teacher is awesome.
I guess that makes up for it.

 

[Livvers]

I learned sin, cosin, and tangent in Geometry 0.o Is Physics hard? I'm debating whether or not to take it....

I found physics to be really easy, actually. I wouldn't be scared of it. Physics was awesome because of how much sense it made to me, and I loved learning how things work.

And my Physics teacher was awesome.

Really, give it a try.

 

[GoldShadow]

So, Goldhsadow, for the first one, I just plug into the calculator sin 30 degrees? and the same for cos and tan? And then what?

Fr the second one, I just arctan 1.2?? This gives me around 50.19. And then just do sinANSWER??

Okay the third one I understand and the fourth one i need to use x = -b + minus square root of b2 - 4 ac divided by 2a?

1) Just plug the values into your calculator. That's it. That's what the answer is. Sin(30) is 1/2, cos(30) is (√3)/2, and tan(30) is (√3)/3. Your calculator will probably give you the decimal values of those, but it's the same thing.

2) Yeah, arctan(1.2). Plug that answer (50.19) into sin, and then into cosine.

3) Yes, once you get all terms on one side. Like so:
0= (v1)Δt + 1/2a(Δt)^2 - d

Then just plug those values into the quadratic formula. Here's what each term corresponds to:
x: t
a: (1/2)a
b: v1
c: -d

You're solving for t.

And since you seem to know your physics could you help me out with one more question?

The takeoff speed of a B747 is about 290km/h.
a) Estimate the acceleration of a fully loaded B747. Can ou justify your estimate.
b) Use you estimate from a) to calculate how long a runway you would have to build for a B747.

This is what I have so far.

a) a = Δv/Δt
a = 290km/h / 35 s (I just made up a number approximately how long it takes for takeoff)
a = 8.29 --> 8.3 km/h/s or about 2.3 m/s^2

b) Δd = v1Δt + 1/2a(Δt)^2
Δd = 0 + 1/2((2.3m/s^2)(35s)^2
Δd = 1.15m/s^2 (1225s^2)
Δd = 1408.75 m

Would this be anaccurate response? Thank you very much !!

I didn't do the math out but your approach seems correct. A few hits on a quick google search said that the runway length for a 747 is around 3000-4000 meters. Your answer is well within an order of magnitude, so it's a perfectly correct answer.

 

[Greenstreet]

i laugh coz this is almost exactly wat we do in maths. physics is easy.. thus the reason i do business/law at uni

 

[Pluvia's other account]

My physics teacher and class was extremely awesome, everything in physics was interesting, I just never quite grasped the sums. I guess if you're good at math, then you're good at physics.

 

[~rh]

I have the easiest Physics teacher this year. And yeah, I'm pretty good at math so I'll be just fine in this class ;D