Sunday

April 20, 2014

April 20, 2014

Total # Posts: 572

**Physics**

A basketball player, standing near the basket to grab a rebound, jumps 73.6 cm vertically. How much time does the player spend in the top 15.4 cm of his jump? I never know which formula to use for these problems! Any help will be greatly appreciated.

**Physics**

Never mind! The mass has nothing do with the problem. I got it. :)

**Physics**

It takes 2.5 s for a small ball released from rest from a tall building to reach the ground. The mass of the ball is 0.05 kg. Calculate the height from which the ball is released. Ok so I have the time, initial velocity, and the acceleration. But the mass totally throws me off...

**Physics**

Ohhh ok I see my mistake! Thanks for your patience. :)

**Physics**

Right. I plug in "1/2 x 3.05 x (2.58^2") and come out with 10.15 m. But that's obviously not correct. I know I'm doing something wrong, but I'm just not sure what. I'm sorry...this just isn't making much sense yet.

**Physics**

Which equation am I using for distance?

**Physics**

Ok, the time I got was 2.624 s. Now what?

**Physics**

What exactly do you mean by "set them equal?"

**Physics**

At the instant a traffic light turns green, a car starts moving with a constant acceleration a of 3.05 m/s^2. At the same time a truck, traveling with a constant speed of 10.15 m/s, overtakes and passes the car. How far beyond the traffic light will the car overtake the truck?...

**Physics**

Now, when I'm solving for time, do I not yet know what v/2 is? Like, it would just be "t = v/2 x -9.8?" I'm so sorry...this is just not making any sense to me yet.

**Physics**

A stone is thrown vertically upward. On its way up it passes point A with speed v, and point B, 12.6 m higher than A, with speed v/2. Calculate the maximum height reached by the stone above point B. I was told the equation to this was "h=1/2(v2)^2/g." However, I’...

**Physics**

So, am I supposed to figure out v2? And what is g, in this case?

**Physics**

A stone is thrown vertically upward. On its way up it passes point A with speed v, and point B, 12.6 m higher than A, with speed v/2. Calculate the maximum height reached by the stone above point B. What equation can I use to get the maximum height?

**Sociology**

What exactly is "cultural purity?" I think I understand the concept, but I'm having a hard time putting it into words.

**Physics**

THANK YOU!

**Physics**

A golf ball released from a height of 1.80 m above a concrete floor, bounces back to a height of 1.06 m. If the ball is in contact with the floor for 4.62 ms, what is the magnitude of the average acceleration a of the ball while it is in contact with the floor? Quidditch told ...

**Physics**

What information must I use to get the velocities?

**Physics**

A golf ball released from a height of 1.80 m above a concrete floor, bounces back to a height of 1.06 m. If the ball is in contact with the floor for 4.62 ms, what is the magnitude of the average acceleration a of the ball while it is in contact with the floor? Do I need to kn...

**Physics**

Ok great, I get it now. Thanks!

**Physics**

**Oops sorry, my sister was using this site last night for Chemistry.

**Physics**

-The brakes on your automobile are capable of creating acceleration of 19 ft/s2. If you are going 76 mi/hr and suddenly see a state trooper, what is the minimum time required to get your car to 55 mi/hr? For this answer, I got 1.62 s. -How far do you travel while returning to ...

**Physics**

THANKS! :)

**Physics**

Ok, so I came up with 16.37 s as my answer for the time. So I do I simply plug that number into the equation 'distance=1/2 x a x t^2' and that is my runway length?

**Physics**

43 knots is 22.097 m/s. So could I now do 22.097 divided by 1.35?

**Physics**

To get how many seconds, would I have to take the 43 knots and divide it by 1.5?

**Physics**

I'm sorry. There was a problem before it where I had to figure out the average acceleration, and that was 1.35 m/s^2. Which fomula can I use to get the length of the runway?

**Physics**

43 knots, right?

**Physics**

The airplane can take off when its airspeed (speed of the air flowing over the wing) is equal to 65 knots. What is the length of runway required for the plane to take off if there is a 22 knots head wind? The runway at the Tallahassee Regional Airport has a length of 8000 ft. ...

**Physics**

N/m, I needed to convert to knots to meters per second. I got the right answer. Thanks for the help, Quidditch. :)

**Physics**

I try this and I get 2.62 knots/s^2, but it says this answer is wrong. Is it?

**Physics**

A Cessna airplane can accelerate from rest to a ground speed of 78 knots in 29.8 s. What is the average acceleration of this airplane? I figured out that 78 knots is equal to 89.76 miles, 144.45 km, or 144,450 m. And I think the equation might be average=delta V over delta t. ...

**Math**

Again, I'm learning about trigonometric functions. I need to find the missing information for each triangle. I have the length of one leg as 24 and the opposite theta as 72. I need to figure out the other angles and side lengths, but I'm really not sure how to.

**Math**

Ok cool, I got that. Thanks a lot. However, this next one gives me the length of one leg (359) and the adjacent theta of 83. How exactly can I solve this?

**Math**

I'm learning about trigonometric functions, and my worksheet instructs me to find the "missing information" for each triangle. For the first one, they give me the length of the hypotenuse (45) and that theta = 35. How can I go about finding the missing info?

**Physics**

A model rocket is launched straight upward with an initial speed of 50 m/s. It accelerates with a constant upward acceleration of 2.00 m/s^2 until its engines stop at an altitude of 150 m. a) What is the max. height reached by the rocket? b) When does the rocket reach max. hei...

**Physics**

Ok so I plugged in the numbers and got 42.1 for a) and -11.4 for b). However, my book says that I got them switched...that 11.4 s is a) and -42.1 m/s is b). How did this happen?

**Physics**

A robot probe drops a camera off the rim of a 239 m high cliff on Mars, where the free-fall acceleration is -3.7 m/s^2. a) Find the velocity with which the camera hits the ground. b) Find the time required for it to hit the ground. Ok so I'm not even sure of which equation...

**Physics**

**Oops, I meant vf+vi. Is that the right equation?

**Physics**

In order to get the time, would I have to do the vf-vi divided by 2, times the distance?? I guess I really do need a brush-up on algebra!

**Physics**

I have the equation 'change in distance = 1/2 x (vf+vi) x change in time (or delta t)' for uniform acceleration. However, I am totally lost when it comes to rearranging it. I need to rearrange it for inital speed (vi) and change in time (delta t). Can someone please help?

**Physics**

A bicyclist accelerates -0.87 m/s/s during a 3.8 s interval. What is the change in velocity of the bicyclist and the bicycle? For this problem, I used the formula 'change in v = a x t" and came up with -3.306 m/s as my answer. Is this right?

**Physics**

Thanks. :)

**Physics**

A freight train traveling with a velocity of -4.0 m/s begins backing into a train yard. If the train's average acceleration is -0.27 m/s/s, what is the train's velocity after 17 seconds? Can someone tell me which formula to use for this?

**Physics**

Ok good. Then, for part B...I got 76.8 for the average velocity. ...I sure hope this is correct...!

**Physics**

So for part A, I got 6.38 hours because I added 3.18, 2.8 (210 km/75) and .40 together. Is this correct?

**Physics**

A bus travels 280 km south along a straight path with an average velocity of 88 km/hr to the south. The bus stops for 24 min, then it travels 210 km south with an average of 75 km/hr to the south. A. How long does the total trip last? B. What is the average velocity for the to...

**Algebra**

Could you explain to me how to these type of problems? I checked in my book and it is still confusing. Evalute the piecewise function at the given value of the independent variable. 1. g(x)= {x^2+2 if x cannont equal 2, x+8 if x=2 Determine g(-5). 2. f(x) {-5x+4 if x <-3, 2...

**Human Services Administrator**

I am having trouble finding information on Government regulations dealing with teen abstinence. The sites given to me by my instructor provided are not giving me the information I need to complete my paper. I have done a search on this but only limited results. You are searchi...

**Science**

Is there an experiment I could do to prove that soap is made up of fat and lye? Thank you for using the Jiskha Homework Help Forum. Here is a recipe for making soap: Recipes From Scratch Basic Recipes Soap Crafters Castile (Non-veggie) 26 ounces of Olive Oil 60 ounces of Lard ...

**Science**

I'v been looking all over the web, but I can't seem to come up with a good response to this: "Describe 2 ways in which maple trees are suited to survive through the winter." Any ideas? Maple trees drop their leaves and the sap stops running in cold weather. T...

**Chemistry**

These are all true or false questions, and I think some of my answers may be wrong. Could someone please check them for me? 1) All stoichiometry calculations are based on STP conditions. (True) 2. Given the amount of reactant, you must use coefficients from the balanced equati...

**Chemistry 3**

How is it possible for me to tell which of these solutes will produce an acidic solution when dissolved in water? LiOH CH3CO2K H2SO3 KOH NaOH NH4NO3 NaOH NaOH can't be the only one... Molecules that produce OH^- when dissolved in water will be basic. Examples:LiOH, KOH, Na...

**Chemistry 2**

Can someone please tell me which of the following I have wrong?? I know that one or more is incorrect, but I'm not sure which ones... Match the following Bronsted acids with their conjugate bases. Choices: SO42-, SO32-, CO32-, HPO42-, HPO32-, Cl-, F-, NO3-, NO2-, HSO4-, HS...

**Chemistry**

In a titration experiment 34.12 mL of 0.902 M KOH is reacted with H2SO4. The endpoint is reached when 50.46 mL of the acid is mixed with the base. What is the molar concentration of the acid? I'm having a hard time even starting this problem, since I don't know the for...

**Algebra 2 once more**

I have more answers that I would like checked. Also, there is one that I'm really confused about. I appreciate any help. :) Rewrite as the log of a single number. 1) 8 ln 2 = ln(2^8) 2) log 42 - log 6 = log 36 (I think this one may be wrong). Evalute each expression w/o a ...

**More Algebra 2**

It would be great if, again, someone would check these answers for accuracy. I'd like to know if I'm doing them right. 1) What equation defines an exponential decay function? a) y=x^pi b) y=pi^-x c) y=(1/pi)^-x d) y=pi times x I think the answer is c. 2) Suppose a lake...

**Algebra 2**

Can someone please check these answers for me?? I'm pretty sure most of them are right, except for maybe the second T/F question... 1) T or F. The domain of y=ln x is equal to the range of y=e (superscript x). True 2) T or F. ln(3x x y to the 3rd power) = (ln x 3) x (ln x)...

**Chem help**

What is the pH of 0.000082 M NaOH? I know how to find the pH of an aqueous solution, but I'm not sure of the formula for this one... What one? Well my question was "What is the pH of 0.000082 M NaOH?," but n/m. I figured out how to do it. Thanks anyway.

**Chemistry**

Icebergs in the North Atlantic present hazards to shipping, causing the length of shipping routes to increase by about 30 percent during the iceberg season. Attempts to destroy icebergs include planting explosives, bombing, torpedoing, shelling, ramming, and painting with lamp...

**Chemistry**

A 63 gram block of an unknown metal at 88 degrees C was dropped into an insulated flask containing approx. 30 g of ice and 30 g of water at 0 degrees C. After the system had reached a steady temp. it was determined that 12.1 g of ice had melted. What is the specific heat of th...

**Chem...one more time**

Ok ok I swear after this I'm done asking questions. It's just that I'm trying so hard to understand all of this, but sometimes it just doesn't make sense to me! So here we go: How many J of energy must be removed when 124.0 g of steam, at a temp. of 167.0 C, is...

**Chemistry**

This is sort of like the one I last posted, only it asks for the final temp. instead of energy... What is the final temp. (in degrees C) after a 15.5 g piece of ice at 0 degrees C is placed into a styrofoam cup with 125.0 g of water initially at 72.0 degrees C? Assume no loss ...

**Chemistry**

Ethanol boils at a temp. of 78.29 degrees C. What amount of energy, in joules, is necessary to heat to boiling and then completely vaporize a 23 g sample of ethanol initially at 12 degrees C? I know that the molar enthalpy heat of vaporization is 35.56 kJ/mol and the specific ...

**Algebra help needed!**

Recall that on some roads, a skid mark of length L ft. indicates that a car was traveling at least s mph, where s is approx. 2 times the square root of 5L. If a car stopped quickly from a speed of 55 mph, about how long would the skid marks be? Please note that we don't do...

**Chem help!!**

A rock salt (NaCl), ice, and water mixutre is used to make homemade ice cream. How many grams of rock salt must be added to lower the freezing point 10.0 degrees C? I have no idea what to do, please help! delta T = Kf*i*m delta T = 10. Kf is the molal freezing point constant, ...

**Chemistry URGENT**

I have to match the items to the statements below, and I'm stuck! My answers are in parentheses, but I know that some of them are wrong. Please help if you know how...I would GREATLY appreciate it! A Dilute B Unsaturated C Saturated D Supersaturated 1. Sodium acetate solut...

**Chemistry**

I have to match the items to the statements below, and I'm stuck! A Dilute B Unsaturated C Saturated D Supersaturated 1. Sodium acetate solution after the excess solute fell out of solution. 2. There is visible solute on the bottom of the container. 3. The solution will re...

**Physics**

Use kx=mg+ma 857x = (5.9*9.8) + (5.9*.81) thus, x= .073

**chemistry check**

1)A pocket of gas is discovered in a deep drilling operation. The gas has a temperature of 480c and is at a pressure of 12.8 atm. What volume of gas is required to provide 18.0 L of gas at the surface where the conditions are 22 C and 1.00 atm? is this correct for number 1? 48...

**science**

Hi I have 2 questions I hope someone can help me :) 1)A pocket of gas is discovered in a deep drilling operation. The gas has a temperature of 480c and is at a pressure of 12.8 atm. What volume of gas is required to provide 18.0 L of gas at the surface where the conditions are...

**Math**

Question 1 : We would like to test 3 different treatments on a particu- lar type of plant. A worker at the local greenhouse will allow us to use 3 among 10 plants. Note: Each treatment will be used on one and only one plant. a) In how many different ways can we assign the plan...

**physics**

Given that the distancef rom Earth to the Moon is 3.8 x 10^8 m, that the Moon takes 27 days to orbit Earth, and that the mass of the Moon is 7.4 x 10^22 kg, what is the acceleration of the Moon and the size of the attractive force between Earth and Moon? Use v = (2pir)/T, wher...

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