bmx

I had gotten an answer that I'm very unsure of so I would like clarification and corrections if necessary. Thank you

1.) A block is sliding along a horizontal frictionless surface at 10.3 m/s. It then slides up an incline that has friction and is tilted at 18.0 degrees. Then it slides onto another horizontal frictionless surface that is 1.50 m above the lower one traveling at 9.13 m/s. What is the coefficient of friction on the ramp?

2.) Superman need to stop Lex Luther who is driving a 1.2x10^4 kg car at 150 km/hr. If he stops the car in 2.3s, how much power did Superman use to stop the car?

3. The attempt at a solution

1.)

KEi - ƩW = PEgf + KEf

1/2mv^2 - μmgcosθ = mghf + 1/2mvf^2

μ = (ghf - 1/2vi^2 + 1/2vf^2)/-gcosθ(hf-hi)

that was the formula I finished with(even though it can be simplified)

I'm just wondering if this is right at all

2.)

P= W/Δt

W= Fd

F= m(vi/Δt)/Δt

d= VavΔt=1/2VfΔt

W= (m(vi/Δt)/Δt)1/2vfΔt

P= ((m(vi/Δt)1/2vfΔt)/Δt

That was my final formula for that. Again, I can simplify it but this would still give the "correct" answer.

Please help!!

I was give a question and cannot find the answer. Please help. It's bothering me so badly!

A mesh cover is made for a tank to keep it free from debris. The cover will rest on the top of the tank and will include a wedge shaped flap that forms a 30 degree angle at the center of the cover. A zipper will go along one side of the wedge-shaped flap and around the arc. Which of the following is closest to the length, in feet, of the zipper.

The radius is 7 feet.

F. 4

G.7

H.11

J.14

k.17

I did (2)(3.141)(7)= 43.9822 for the circumference

then did 30/360 = 0.0833333 for the arc angle ratio

then (43.9833)(0.0833333) = 3.6652 for the arc length, multiplied it by 2 for the zipper length and got 7.3305 feet.

G is clearly the closest to that but apparently the answer is H - 11. Could someone show me what I did wrong

There were a few problems I was having when I was doing my AP government assignment. Not trying to cheat, I just want some clarifications

T or F question

The espionage Act of 1917 was part of U.S. entry into World War I

I feel this is true because the Act was passed just after U.S. entered the war and it did deal with speaking against government in this war and made it illegal to refuse conscription. I am just unsure whether it was a direct part of U.S. entry. I think I may be over-thinking this and it may be true but I'd like help

mult. choice

The framers saw no need for a bill of rights because

a. in their view, civil liberties were a matter for the states, not for federal government

b. they were convinced that in a democratic republic, public opinion was a sufficient protection.

c. they assumed that the federal government could not do things that it was not explicitly authorized to do.

d. their chief concern was protecting public order, not guaranteeing rights.

This question baffles me because a few answers seem to be correct or close to. A seems the best choice because I know that the Framers didn't want a bill of rights partly because they believed the states bill of rights were sufficient in protecting civil liberties(which was their only true goal). I'm not sure about that answer though. I am fairly certain it is not D because the fact they wanted to protect civil liberties not necessarily public order. C seems very good too however because I have read that people were shocked when a democratic republic government stepped outside its authority. They believed it protected their civil liberties in what was in the constitution alone. So if there's anyway you can help, I greatly appreciate it!

Δx = vi(cosƟ)Δt

Δy = 1/2aΔt^2

solve for Δx in terms of Ɵ, Δy, vi, and a.

I'm having difficulties solving in terms of Δx, could you please show me how to do it? I don't care too much about the answer, my teacher already gave me it, but I just want to know how I'm supposed to get there for future reference. Thanks!

given f(x) = 5x+2 and g(x) = x^2-3, which of the following is an expression for f(g(x))

I know the answer is 5x^2-13

I know no logical way to get to that answer so I need help please. Explain how you get there too. I'm really good at math, especially calculus but for some reason I don't know how to do this problem:/

There are 2 questions on my review guide for my technology class I can't seem to remember/

True or False

1. The reset pin on the 555 timer should be pulled low to reset the timer.

2. The trigger pin on a monostable 555 must go high in order to trigger the pulse.

I know that if a trigger pin goes high, the output goes low, and vice versa. But I'm not sure whether it is high or low that sets off a pulse or resets it. I marked false for both but it doesn't work with me not to be 100% sure.

im really good at math but i cant figure out what i did wrong with this one..

In a tournament, each of the 6 participants played 2 matches against each of the other participants. What was the total number of matches played during the tournament?

I did 5+4+3+2+1 to get 15 then multiplied that by 2 to get 30 because you would of already played someone every time you went to a different person and you cant play yourself. and multiply by 2 for the 2 matches each time. apparently that isn't correct. i know what answer is. tell me what you got and how you got it because i cant figure it out.

if not what would it be?

Also. Is a democratic government even possible in an economically polarized society?

All the fatalities that say "jump" or involve jumping never work for me... I just can't get it. Is there something specific your supposed to press?

if you end ta sentance with lets say etc. do you put a period after or do you keep it as it is because theres already a period.

ex: food, money, etc.

or

food, money, etc..