Tuesday

April 28, 2015

April 28, 2015

Total # Posts: 339

**Physics**

The maximum speed of a 3.68-kg mass attached to a spring is 0.688 m/s, and the maximum force exerted on the mass is 11.6 N. What is the amplitude of motion for this mass? (in m) What is the force constant of the spring? (in N/m) What is the frequency of this system? (in Hz)
*April 26, 2015*

**Physics**

A large pendulum with a 200-lb gold-plated bob 12 inches in diameter is on display in the lobby of the United Nations building. Assume that the pendulum has a length of 78.4 ft. It is used to show the rotation of the Earth - for this reason it is referred to as a Foucault ...
*April 26, 2015*

**Physics**

Steam of mass 11.0 g at 100°C is added to 126.7 g of ice at 0.00°C. Find the final temperature of the system.
*April 22, 2015*

**Physics**

After you pick up a spare, your bowling ball rolls without slipping back toward the ball rack with a linear speed of = 3.18 m/s. To reach the rack, the ball rolls up a ramp that rises through a vertical distance of = 0.510 m. What is the linear speed of the ball when it ...
*April 20, 2015*

**Physics**

A 10.4-g CD with a radius of 5.85 cm rotates with an angular speed of 33.8 rad/s. What is its kinetic energy? (in J) I need help with this question. I thought you would just use K=1/2mv^2 but when I use m=0.0104kg and v=33.8 I get 5.94 which isn't the correct answer....
*April 20, 2015*

**Physics**

A person exerts a tangential force of 34.8 N on the rim of a disk-shaped merry-go-round of radius 2.60 m and mass 152 kg. If the merry-go-round starts at rest, what is its angular speed after the person has rotated it through an angle of 30.4°? (in rad/s)
*April 20, 2015*

**biology**

Certain insect species have become more and more resistant to insecticides. What type of natural selection is this, and how does it differ from the other types?
*April 15, 2015*

**Chemistry**

What is a balanced equation for a Base-Acid Titration?
*April 2, 2015*

**Chemistry**

Just out of curiosity DrBob222, are you a even real doctor?
*March 27, 2015*

**Chemistry**

I just needed help, not your opinion if I can do it or not.
*March 27, 2015*

**Chemistry**

Well I figured out the equations, I just have no clue on what to do about the "design an experiment" part
*March 27, 2015*

**Chemistry**

Tetraphosphorus (P4), commonly known as white phosphorus, forms different compounds with chlorine (Cl2) depending on the amount of chlorine present. If chlorine is limited, phosphorus trichloride (PCl3) is formed. If there is an excess of chlorine, phosphorus pentachloride (...
*March 27, 2015*

**Physics**

A small box is held in place against a rough wall by someone pushing on it with a force directed upward at 29.8° above the horizontal. The coefficients of static and kinetic friction between the box and wall are 0.400 and 0.320, respectively. The box slides down unless the...
*February 15, 2015*

**Physics**

What is the magnitude of the acceleration of two falling sky divers (mass 149 kg including parachute) when the upward force of air resistance is equal to one fourth of their weight? (in m/s^2) After popping open the parachute, the divers descend leisurely to the ground at ...
*February 10, 2015*

**Physics**

An elevator (mass 5000 kg) is to be designed so that the maximum acceleration is 0.0620 g. What is the maximum force the motor should exert on the supporting cable? (in N) What is the minimum force the motor should exert on the supporting cable? (in N)
*February 10, 2015*

**Physics**

I don't understand how to begin these problems. I'm terrible at physics. Just looking for a little help and you are so rude. If you aren't looking to help kids do/understand their homework you shouldn't be on this site DrBob222.
*February 10, 2015*

**Physics**

A 0.133 kg baseball traveling 30.6 m/s strikes the catcher's mitt, which, in bringing the ball to rest, recoils backward 11.4 cm. What was the average force applied by the ball on the glove? (in N)
*February 10, 2015*

**Physics**

A place kicker must kick a football from a point 35.0 m (= 38.3 yd) from the goal, and the ball must clear the crossbar, which is 3.05 m high. When kicked, the ball leaves the ground with a speed of 19.8 m/s at an angle of 45.0o to the horizontal. By how much does the ball ...
*February 1, 2015*

**Physics**

A projectile is launched with an initial speed . At its highest point, the projectile's speed is . What was the launch angle above the horizontal? (in deg)
*February 1, 2015*

**Physics**

Riding in an elevator, a man notices that he feel heavier or lighter based when the elevator speeds up or slows down. He stands on a bathroom scale in the elevator to take some measurements. Assume that his mass is 85 kg. a. What is this man’s weight while at rest? b. ...
*February 1, 2015*

**Algebra**

$20, $25, $30, $21, $10, $15, $11, $5, $6, $1
*February 1, 2015*

**Physics**

In the picture to the right, a ring pulls a box of mass m = 5.0 kg across a level table. The string pulls with a tension F = 25.0 N at an angle θ = 25˚ above the horizontal. A frictional force of 4.0 N also acts on the box. Calculate a. the normal force on the box. b...
*January 31, 2015*

**Physics**

A bird sits at rest in the middle of a wire. The wire slopes upward at 5* from the horizontal on either side of the bird. If the wire on both sides of the bird is experiencing a tension force of 106 N, then what is the mass of the bird?
*January 31, 2015*

**Physics**

He is standing at the edge of a rose garden at H = 4.62 m below her window and at D = 5.21 m from the base of the wall. How fast are the pebbles going when they hit her window?
*January 21, 2015*

**physics**

A diver running 1.89 m/s dives out horizontally from the edge of a vertical cliff and 2.88 s later reaches the water below. How high was the cliff. (in m)
*January 21, 2015*

**physics**

The components of a vector V are often written (Vx, Vy, Vz). What is the x component of a vector which is the sum of the two vectors, V1 and V2, whose components are (3.27, 1.86, 0.00) and (3.85, -3.53, -1.43)?
*January 21, 2015*

**chemistry**

How much work is done at 1.2 atm and 316 K when 1 mole of propane undergoes combustion? C3H8 (l) + 5O2 (g) → 3CO2 (g) + 4H2O (l)
*January 21, 2015*

**Physics**

A particle moves along the x axis. Its position is given by the equation x = 2.00 + 3.20t - 3.85 t2 with x in meters and t in seconds. Determine its position at the instant it changes direction. (in m)
*January 19, 2015*

**Physics**

A speedboat moving at 29 m/s approaches a no-wake buoy marker 98.3 m ahead. The pilot slows the boat with a constant acceleration of -3.61 m/s2 by reducing the throttle. How long does it take the boat to reach the buoy? (in s)
*January 19, 2015*

**Physics**

A driver in a car traveling at a speed of 56.1 mi/h sees a deer 103 m away on the road. Calculate the minimum constant acceleration that is necessary for the car to stop without hitting the deer (assuming that the deer does not move in the meantime). (in m/s^2)
*January 19, 2015*

**Physics**

A stone is dropped from the top of a cliff. It hits the ground below after 3.12 s. How high is the cliff? (in m)
*January 19, 2015*

**Physics**

In coming to a stop, a car leaves skid marks 97.0 m long on the highway. Assuming a deceleration of 6.60 m/s2, estimate the speed of the car just before braking. (in m/s)
*January 19, 2015*

**Physics**

At highway speeds, a particular automobile is capable of an acceleration of about 1.52 m/s2. At this rate, how long does it take to accelerate from 74.0 km/h to 104.0 km/h? (in s)
*January 19, 2015*

**chemistry**

22.0 grams of zinc reacted with 95.0 mL of 0.5 Molarity HCl. What volume of hydrogen gas would be produced at 22 degrees C and 745 torr?
*January 5, 2015*

**To Morgan**

bless your soul. Dr. Bob is rude af (sometimes)
*December 12, 2014*

**Calculus**

A deposit of $5,000 at 4% interest compounded continuously will grow to V(t) = 5000e^0.04t dollars after t years. Find the average value during the first 20 years (that is, from time 0 to time 20). (Round your answer to the nearest cent.)
*December 10, 2014*

**Algebra 2**

a person throws a baseball into the air with an initial vertical velocity of 30 feet per second and then lets the ball hit the ground. The ball is released 5 feet above the ground. How long is the ball in the air?
*December 9, 2014*

**Freshman Algebra**

Using a chart: At noon a private plane left Austin for Los Angeles,2100km away, flying at 500km/h. One hour later a jet left Los Angeles for Austin at 700km/h. At what time did they pass each other?
*November 12, 2014*

**algebra**

So no i wasn't guessing lol
*October 22, 2014*

**algebra**

No I put the question mark there because I didn't know if it was right or not.
*October 22, 2014*

**algebra**

A. 95.s and 108.7s B. 10.2s and 101.9s C. 108.7s and 10.2s D. 95.1s and 10.2s Answer: A?
*October 22, 2014*

**algebra **

starting from 1.5 miles away, a car drives toward a speed checkpoint and then passes it. The car travels at a constant rate of 53 miles per hour. The distance of the car from the checkpoint is give by d=|1.5-53t|. At what time if the car o.1 miles from the checkpoint? Answer ...
*October 22, 2014*

**Economics**

Suppose that you are a bicycle producer. In 2 or 3 sentences, explain why you are willing to supply the most bicycles at the highest price
*October 20, 2014*

**College Algebra**

When MyKing Burgers charges a price p dollars for one of its burgers, its revenue in dollars is given by R(p) = −200p(p − 10) For what prices does the company have no revenue? for this problem do i set the equation at 0=-200p(p-10) and solve from there?
*October 12, 2014*

**Math (Finding the Inverse)**

I have the equation: 2x^2 + 3y^2 = 4 What would the inverse equation be? Any help would be great.
*September 21, 2014*

**math**

3=100 thousands and 3=10 thousands
*September 17, 2014*

**Math - Finding the Equation**

If.... f(x) = x + 2 and g(x) = −x^2 + 2x − 3, determine - ( f ∘ g)(−2) - a formula for (g∘f)(x) My answer for ( f ∘ g)(−2) = -9 But I don't know how to get the formula for (g∘f)(x). Any help would be great.
*September 9, 2014*

**NJHS**

hey. I am running for the vice-president for NJHS. I have already gotten my introduction, and first two body paragraphs done. I can not come up with a good third body paragraph and I need help with my conclusion as well.I just need to know what should I include in the third ...
*September 4, 2014*

**math**

un Lanes Bowling charges a fee of $4 to use their shoes and $6 for each game played. Salim wants to figure out how much it will cost him to bowl. Part 1: Write an equation representing this problem. Let x be the number of games bowled, and let y be the total cost. Part 2: Is x...
*June 17, 2014*

**Chemistry**

If a balloon filled with carbon dioxide has occupies a volume of 31 L at STP, what is the mass of the gas?
*April 21, 2014*

**Chemistry**

Hydrogen peroxide(H2O2) slowly decomposes to form water and oxygen gas. Calculate the mass of Hydrogen peroxide needed to obtain 0.460L of oxygen gas at STP
*April 21, 2014*

**Trig Identities**

Explain why Sin of theta= -The square root of 1-cos^2 theta is not an identity, using either graphical or numerical reasoning.
*March 25, 2014*

**Trigonometry**

-12/13?
*March 25, 2014*

**Trigonometry**

Suppose that (5/13,y) is a point in Quadrant IV lying on the unit circle. Find y. Write the exact value not a decimal approximation
*March 25, 2014*

**Chemistry**

I tried working this question out with the help already provided, but I couldn't ever get the right answer. If you could possibly explain how to do the problem step by step and include the right answer, I'd greatly appreciate it. Thanks! What mass of sodium benzoate ...
*March 13, 2014*

**Chemistry**

I tried working out the problem and was unable to get the correct answer. Could you possibly work it out entirely? I don't know what I'm doing wrong.
*March 3, 2014*

**Chemistry**

What mass of sodium benzoate should be added to 160.0mL of a 0.17M benzoic acid solution in order to obtain a buffer with a pH of 4.30?
*March 3, 2014*

**world history**

During the early 1800s, the United States tried to make peace with other countries in order to grow and develop. Give an example of one of these peace efforts and briefly explain what it hoped to accomplish
*February 7, 2014*

**math**

gail is cooking a healthy snack. she adds 2/3 cup of raisins and 6/7 cup of peanuts. Estimate the total amount that gail adds.
*January 30, 2014*

**Math**

1/2 3/7 7/9 1/12
*January 13, 2014*

**Science**

This actually helps a lot, it's not that we don't study but really the school doesn't always provide enough information and if they do it's difficult to find. I knew most of the questions on the test, but some I had no clue how to answer.
*November 6, 2013*

**science**

A small rocket is fired directly upwards with an initial velocity of 100m/s. How many seconds will it take to reach its maximum height?
*October 2, 2013*

**Chemistry**

Calculate the number of phosphorus atoms in 17.0g sample of calcium phosphate
*September 29, 2013*

**Chemistry**

How many potassium atoms in 7.50g of potassium chromate?
*September 29, 2013*

**Chemistry**

How many atoms of hydrogen are in a mixture of 3.49x10^23 molecules of H2O and 78.1g of CH3OH?
*September 29, 2013*

**algebra**

5x - 7 (2 - 4x)
*September 18, 2013*

**geometry**

Need help with a word problem - Carrie collected can food for a homeless shelter each day for one week. On day one she collected 7 cans, on day two she collected 8 cans, on day three she collected 10 cans and on day four she collected 13 cans. If Carrie wanted to give at least...
*September 8, 2013*

**Calculus**

thanks
*August 29, 2013*

**Calculus **

Differentiate: y=sin(2z)+cos^2z
*August 29, 2013*

**math**

A triangle has two sides with equal length and a third side 16 meters long. If the perimeter is 42 meters, what is the length of each of the equal sides?
*July 7, 2013*

**chemistry**

A gas occupies 560.0 mL at 285 K. To what temperature must the gas be lowered if it is to occupy 250.0 mL? Assume that the pressure remains constant.
*July 3, 2013*

**chemistry**

A balloon at 32 °C is filled with 21 L of air. What would its volume be at a temperature of 52 °C, assuming pressure remains constant?
*July 3, 2013*

**chemistry**

A gas has a pressure of 0.370 atm at 50.0 °C. What is the pressure at 22 °C, assuming volume remains constant?
*July 3, 2013*

**chemistry**

If 21.0 L of gas is held at a pressure of 7.80 atm and a temperature of 900.0 K, what will be the volume of the gas if the pressure is decreased to 4.50 atm and temperature decreased to 750.0 K?
*July 3, 2013*

**statistics & probability**

according to a survey, 30% of 18-25 year olds have blue eyes. In a random sample of 8 people in this age group what is the probability that exactly 0 have blue eyes?
*June 27, 2013*

**writing**

Using elipsess and brackets Add punctuation to the following excerpt. Writing under the name of Diedrich Knickerbocker Washington Irving aimed his potent satire at as diverse topics as political rivals such as Thomas Jefferson to the very ideal of looking back on the past ...
*June 14, 2013*

**geometry**

Which of the following statements is true?Select one of the options below as your answer:A. A 25o angle is congruent to a 25o angle. B. Two intersecting lines form two pairs of congruent angles. C. It is possible for congruent angles to add up to 90o. D. All of the above are ...
*June 12, 2013*

**Math**

A math class has girls and boys in the seventh grade and girls and boys in the eighth grade. The teacher randomly selects a seventh grader and an eighth grader from the class for a competition. What is the probability that the students she selects are both girls? Write your ...
*May 1, 2013*

**Physics-- please help me finish!!**

Ive tried using the formulas my teacher gave me, however I can't seem to get the right answers. Please help! A 1.4-kg block hangs from a spring. A 363-g body hung below the block stretches the spring 2.6 cm farther. What is the spring constant? When the 363-g body is ...
*April 26, 2013*

**chemistry**

The question I am having trouble with is: Scientists originally were uncertain whether the oxygen gas produced during photosynthesis came from CO2, H2O, or from both. How could radioisotope tracers be used to settle that question? Chemistry - DrBob222 6CO2 + 6H2O ==> ...
*April 15, 2013*

**Chemistry**

The question I am having trouble with is: Scientists originally were uncertain whether the oxygen gas produced during photosynthesis came from CO2, H2O, or from both. How could radioisotope tracers be used to settle that question?
*April 14, 2013*

**Chemistry**

Calculate the mass of 0.0122 moles of: a) Si3N4 b) (CH3)3 N
*April 2, 2013*

**Pre-Algebra **

What association would you expect if graphing height and weight?
*March 19, 2013*

**honors algebra**

the area of a triangle is 105 square feet. the height is two more than four times the base. find the base and height of the triangle
*March 6, 2013*

**Physics**

An air-track cart of mass 0.10 is moving with a speed 1.2 to the right when it collides with a cart of mass 0.24 that is at rest. Each cart has a wad of putty on its bumper, and hence they stick together as a result of their collision. Suppose the average contact force between...
*March 2, 2013*

**chemistry**

Suppose of copper (II) nitrate is dissolved in of a aqueous solution of sodium chromate. Calculate the final molarity of nitrate anion in the solution. You can assume the volume of the solution doesn't change when the copper (II) nitrate is dissolved in it. Round your ...
*February 19, 2013*

**Physics**

A person stands 2.0 m away from the reflecting surface of a plane mirror. What are the image characteristics?
*February 13, 2013*

**Physics**

A small dog sits 1.5 m in front of a plane mirror. Where is the dog's image in relation to the mirror?
*February 13, 2013*

**Physics**

A woman 2.00 m tall stands 3.5 m in front of a plane mirror. (a) What is the minimum height the mirror must be to allow the woman to view her complete image from head to foot? Assume that her eyes are 10 cm below the top of her head.(b) What would be the required minimum ...
*February 13, 2013*

**Physics**

A woman fixing her hair holds a plane mirror 30 cm away from the front of her face so as to look into a plane mirror on the bathroom wall behind her. She is 90 cm from the wall mirror. Approximately how far does the image of the back of her head appear in front of her?
*February 13, 2013*

**Math**

What is the rule for 2 to 3 and 9 24.
*February 12, 2013*

**dakota valley**

what is areoglhmet
*February 12, 2013*

**physics**

(part 1) An athlete whirls an 8.1 kg hammer tied to the end of a 1.4 m chain in a horizontal circle. The hammer moves at the rate of 0.597 rev/s. What is the centripetal acceleration of the hammer? Assume his arm length is included in the length given for the chain. Answer in ...
*February 12, 2013*

**Physics**

An Olympic skier moving at 19 m/s down a 26 degree slope encounters a region of wet snow and slides 136 m before coming to a halt. What is the coefficient of friction between the skis and the snow? ( g = 9.81 m/s2)
*January 27, 2013*

**Math**

4y is 55 percent of what number
*January 7, 2013*

**Math**

I have a garden that is 50 ft x 18 ft and my friend has a garden that is 30 ft X 15 ft. Why is the area of my garden twice the size of my friend's garden?
*December 11, 2012*

**Science**

as you push a lawn mower , the horizontal force is 300n, if you push the mower a distance of 500m, how much work do you do?
*November 18, 2012*

**physics pre-ap**

A(n) 1100 kg car is parked on a 4 incline. The acceleration of gravity is 9.8 m/s2 . Find the force of friction keeping the car from sliding down the incline. Answer in units of N
*November 15, 2012*

**Physics **

The Trans-Alaskan pipeline is 1300 km long, reaching from Prudhoe Bay to the port of Valdez, and is subject to temperatures ranging from -72°C to +38°C. (a) How much does the steel pipeline expand due to the difference in temperature? (The coefficient of linear ...
*November 14, 2012*