# Zac

Most popular questions and responses by Zac-
## Math

Riddle: It’s 7:00 am. You are asleep and there is a sudden knock on the door. Behind the door are your parents, who came to have breakfast. In your fridge: bread, milk (pasteurised!), juice, and a jar of jam. To answer, what will you open first?

*asked on December 4, 2018* -
## Literacy

think about the various conflicts in dragonwings. identify and describe one event from the novel that represents a cause and effect relationship that creates conflict. explain the effect the conflict has on other characters in the story.

*asked on May 9, 2016* -
## Physics

A block of mass m = 2.00 kg rests on the left edge of a block of mass M = 8.00 kg. The coefficient of kinetic friction between the two blocks is 0.300, and the surface on which the 8.00- kg block rests is frictionless. A constant horizontal force of

*asked on July 25, 2012* -
## Statistics

5. Scores on a recent national statistics exam were normally distributed with a mean of 80 and a standard deviation of 6. a. What is the probability that a randomly selected exam will have a score of at least 71? b. What percentage of exams will have

*asked on March 5, 2012* -
## math

kevin had a board that was 5 and 1/4 feet long. while making making a fence, he cut a peice 3 and 3/4 feet long from the board. what was the lenth of the peice of board remained?

*asked on May 7, 2012* -
## algebra 2

Factor x3 4x2 3x + 18 = 0, given that 3 is a zero.

*asked on January 10, 2011* -
## physics

A point charge of -4.00 is at the origin, and a second point charge of 6.00 is on the axis at = 0.850 . Find the magnitude and direction of the electric field at each of the following points on the axis. a) x=25.0cm b) x=1.10m c) x=-15.0cm

*asked on February 10, 2013* -
## algebra

According to the rational root theorem, which is not a possible rational root of x3 + 8x2 x 6 = 0?

*asked on January 10, 2011* -
## calculus

A stone is thrown straight down from the edge of a roof, 750 feet above the ground, at a speed of 7 feet per second. A. Remembering that the acceleration due to gravity is -32 feet per second squared, how high is the stone 5 seconds later? B. At what time

*asked on April 26, 2012* -
## Physics

Mass 1 and mass 2 are connected as shown by a massless, non-stretch rope that passes over a massless, frictionless pulley. The masses are on inclines which have friction. When the angles of the string are as given, mass 1 experiences an acceleration up the

*asked on July 25, 2012* -
## physics

A hawk ﬂies in a horizontal arc of radius 15.7 m at a constant speed of 3.8 m/s. Find its centripetal acceleration. Answer in units of m/s 2 006 (part 2 of 2) 10.0 points It continues to ﬂy along the same horizontal arc but increases its speed at the

*asked on February 2, 2012* -
## PHYSICS

A student (m = 63 kg) falls freely from rest and strikes the ground. During the collision with the ground, he comes to rest in a time of 0.0170 s. The average force exerted on him by the ground is +16500. N, where the upward direction is taken to be the

*asked on October 21, 2010* -
## Physics

A popular carnival ride consists of a large, round room that rotates fast enough that any person standing against the wall will be stuck there, even as the floor is dropped away from their feet. The coefficient of static friction between the person and the

*asked on July 26, 2012* -
## Physics

A car with fuzzy dice hanging from the rear view mirror by a single string drives along at a constant 25.0 m/s. a) If the dice have a mass of 0.030 kg, what is the angle of the string (relative to vertical)? b) What is the tension in the string? c) As the

*asked on July 26, 2012* -
## physics

With what frequency would you have to push a child on a swing that had supporting chains that were 2.3 m long? Express your answer in Hz to 3 significant digits.

*asked on April 7, 2016* -
## physics

A mass hung from a spring stretches the spring by 11 cm when the mass is resting at its equillibrium position. What will be the frequency of oscillation of this system if the mass is put in motion?

*asked on April 3, 2016* -
## Physics

In the Daytona 500 car race in Daytona, FL, a curve in the oval track has a radius of 316 m (near the top of the curve) and is banked at 31.0 O . a) What speed would be necessary to make this turn if there was no friction on the road? b) If the coefficient

*asked on July 26, 2012* -
## Geography

i need to label a diagram of the drainage basin of the River Tees. the words i have got to use are:- Tributary Mouth Confluence Source Reservoir Also i need to colour the diagram to show the relief of the drainage basin. A)Shade the river and its

*asked on January 30, 2009* -
## Pre-Calc

Convert r=1+3sin2x from a polar equation to a rectangular equation.

*asked on January 6, 2013* -
## Physics

Assume the Earth is a perfect sphere of radius 6,400 kilometers. Find the weight of a 75.0 kg person at the North pole. Find the weight of this same person at the equator. (You don't need to use Newton's Law of Gravitation but you do need to analyze the

*asked on July 26, 2012* -
## Physics

Starting from rest, a 6.70 kg object falls through some liquid and experiences a resistive (drag) force that is linearly proportional to the velocity of the object. It's measured that the object reaches half its terminal speed at 4.50 s. a) What is the

*asked on July 26, 2012* -
## Chemisty (please read soon)

which will become a buffer in 1L of H2O? a) 0.3 mole KOH & 0.3 mole HBr b) 0.5 mole NH3 & 0.5 mole HCl c) 0.2 mole NaCl & 0.3 mole HCl d) 0.2 mole NaOH & 0.2 mole HBr e) 0.4 mole HC2H3O2 & 0.2 mole NaOH I think that the answer is e. Is that correct?

*asked on April 29, 2012* -
## calculus

A trough has a trapezoidal cross section with a height of 5 m and horizontal sides of width 2.5 m and 5 m. Assume the length of the trough is 14 m. How much work (in joules) is required to pump the water out of the trough (to the level of the top of the

*asked on July 23, 2012* -
## Physics

A 86.0-kg man is riding an escalator in a shopping mall. The escalator moves the man at a constant velocity from ground level to the floor above, a vertical height of 5.50 m. What is the work done on the man by each of the following forces?

*asked on February 11, 2011* -
## physics

A block is hung by a string from the inside roof of a van. When the van goes straight ahead at a speed of 26 m/s, the block hangs vertically down. But when the van maintains this same speed around an unbanked curve (radius = 135 m), the block swings toward

*asked on October 6, 2010* -
## algebra 2

A bag contains 4 white marbles, 3 red marbles, 2 green marbles, and 1 yellow marble. what is the probability of reaching in the bag and randomly choosing a white marble?

*asked on March 15, 2010* -
## physics

A certain pendulum on Earth has a period of 1.6 s. What would be the period of this pendulum if it were taken to another planet that had 1.75 times the mass of the Earth and 2.5 times the Earth's radius? Express your answer in seconds to three significant

*asked on April 7, 2016* -
## statistics

A random sample of 100 students from a high school was selected. If a 98% confidence interval estimate for the mean age of students is calculated to be 14.2511 to 14.9489, then the standard deviation of the sample mean is?

*asked on November 17, 2013* -
## PHYSICS

A model rocket is constructed with a motor that can provide a total impulse of 25.5 N · s. The mass of the rocket is 0.213 kg. What is the speed that this rocket achieves when launched from rest? Neglect the effects of gravity and air resistance.

*asked on October 21, 2010* -
## math

how do i write 53 hundredths as a decimal.

*asked on February 2, 2010* -
## Cal

Express the given quantity in a single logarithm. ln(a + b) + ln(a - b) - 2 ln c

*asked on October 5, 2011* -
## PHYSICS

A stream of water strikes a stationary turbine blade horizontally, as the drawing illustrates. The incident water stream has a velocity of +18.0 m/s, while the exiting water stream has a velocity of -18.0 m/s. The mass of water per second that strikes the

*asked on October 21, 2010* -
## physics

A simple harmonic oscillator has a frequency of 2.05 Hz. What will be its amplitude of oscillation if it's started from its equillibrium position with a velocity of 1.9 m/s? Express your answer in m to three significant digits.

*asked on April 7, 2016* -
## math

A and B weigh 156 pounds. A and C weigh 171 pounds. How much do they each weigh if the total weight is 255 pounds?

*asked on September 16, 2014* -
## Physics

A box starting from rest, slides down an incline which makes an angle of θ above the horizontal. The incline has a maximum height of h above the platform on which it sits which is itself H above the ground. The box leaves the end of the ramp and

*asked on July 25, 2012* -
## math

If Sally can paint a house in 4 hours, and John can paint the same house in 6 hour, how long will it take for both of them to paint the house together? This the ans 2 hours and 24 minutes but how did they work it out?

*asked on January 26, 2011* -
## Chemistry

Determine the freezing point of an aqueous solution containing 10.50 g of magnesium bromide in 200.0 g of water.

*asked on August 31, 2015* -
## calculus

Find parametric equations for the line that is perpendicular to the plane 2x-y+3z=7 and intersects the plane when x=1 and y=1.

*asked on January 15, 2013* -
## Physics

A 12.0 kg block sits on a frictionless table. On top of this block is placed a 5.00 kg block. The coefficient of static friction between the two blocks is 0.70. a) What is the maximum force that can be applied horizontally to the 5.00 kg block before it

*asked on July 25, 2012* -
## Physics

Seawater has a bulk modulus of 2.34×109 N/m2. Its density at 5°C is 1030 kg/m3. What is the speed of sound through seawater at this temperature?

*asked on June 16, 2012* -
## Chem (please read soon)

50.0mL of 0.1 molar NaOH is added with 50.0mL of 0.1 molar CH3COOH. The Ka = 1.8*10^-5. what is the pH of the solution? a) 7.00 b) 9.22 c) 4.77 d) 8.22 e) 5.78 I think that the answer is d. Would i be safe in saying that?

*asked on April 29, 2012* -
## math

If Sally can paint a house in 4 hours, and John can paint the same house in 6 hour, how long will it take for both of them to paint the house together?

*asked on January 26, 2011* -
## physics

In getting ready to slam-dunk the ball, a basketball player starts from rest and sprints to a speed of 6.2 m/s in 1.9 s. Assuming that the player accelerates uniformly, determine the distance he runs.

*asked on September 7, 2010* -
## Biochemistry

explain why a strong acid or base can denature an enzyme explain how varying pH influenced the rate of the catalase reactions and explain why. explain the influence of temperature in excess of 50 degrees C on the influence of most enzyme controlled

*asked on October 28, 2009* -
## statistics

Consider an upper-tail test of hypothesis for the difference in two population means. The sample data from the first population is: n = 50, x-bar = 110, s = 10. The sample data from the second population is: n = 75, x-bar = unknown, s = 11. We conclude the

*asked on November 28, 2016* -
## calculus

Find the parametric equations for the line that contains the point (3,1,-4) and is parallel to the line r(t)=(1+2t)i+(-3-t)j+(5+5t)k

*asked on January 15, 2013* -
## physics

A 125 kg flatbottomed boat is floating along at 5.0 m/s, headed east. Sally Sue, standing at one end of the boat, starts to walk at 2.0 m/s, also to the east. If Sally’s mass is 65 kg, what is the speed of the boat as she walks along?

*asked on August 3, 2012* -
## Chemistry

0.200 moles of NaF are added to 1L 2.0 molar HF. The Ka = 7.2*10^-4. What is the pH? a) 2.14 b) 6.70 c) 10.80 d) 3.00 e) 7.00 I got 4.14. pH = -log(Ka)-log([NaF]/[HF]) ==> pH = -log(7.2*10^-4)-log(.2/2) ==> pH = 4.14 Or did I do something wrong?

*asked on April 29, 2012* -
## Chemistry

50.0mL of 0.01M Ba(OH)2 is added to 150.0mL of 0.01M HNO3. What is the new pH of the solution?

*asked on April 29, 2012* -
## Physics

How long does it take a 23 kW steam engine to do 8.8 x 10^7 J of work?

*asked on January 4, 2012* -
## chemistry

25 ml HCl x 1L/1000mL x .200HCl/1L = .005 mol HCl. Using the balanced equation from this, how many moles of NaOh will you need to completely neutralize the HCl?

*asked on November 10, 2010* -
## math

What is the mean mediam and mode for 64,75,62,90,81,52,80,99,100,65,75,61,0,106,72,70,80,92,90,102

*asked on May 11, 2010* -
## algebra

pleae help solve: 3x-5y=7 and 5x-2y=-1

*asked on January 6, 2010* -
## Calculus - Differentiation

Differentiate: y = 3/(1-6x^4)

*asked on February 2, 2015* -
## chemistry

A sample of 131 I was purified and then analyzed for iodine content. It was found that the sample was 99.8% pure. 25 hours later the sample was tested again and it was found that the sample was now just 78.2% pure. What is the half - life of 131 I?

*asked on February 1, 2015* -
## Physics

A skateboarder moving at 7.18 m/s along a horizontal section of a track that is slanted upward by 48.5 ° above the horizontal at its end, which is 0.741 m above the ground. When she leaves the track, she follows the characteristic path of projectile

*asked on October 16, 2014* -
## Math

The denominator of a fraction is four more than twice the numerator. If both numerator and denominator are increased by six, the simplified result is 7/13. Find the original fraction

*asked on February 24, 2014* -
## Chemistry

A student begins with 25 mL of a 0.434 M solution of HI and slowly adds a solution of 0.365 M NaOH. 1. What is the pH after 15.00 ml of NaOH solution has been added? 2. What is the pH after 40 ml of NaOH solution has been added?

*asked on June 3, 2013* -
## calculus

For what values of z will (2-z)-y = 0 4x+(1+z)y = 0 have an infinite number of solutions.

*asked on January 15, 2013* -
## math

the high of a trapezoid is 10ft the upper base is 6ft shorter then the lower base if the area of the trapezoid is 50 square ft how long is the upper and lower base?

*asked on October 1, 2012* -
## Physics

Consider a spider walking from the top of a (stationary) beach ball. (Let that angular position = 0 O .) The spider finds it loses its grip when the normal force between it and the surface is less than 1/2 of its weight. At what angle does this slipping

*asked on July 26, 2012* -
## Physics

An ice skater slides (without pushing) across a frozen pond for 25.0 m before coming to a stop. If the coefficient of kinetic friction is 0.050, how fast was the skater initially moving?

*asked on July 24, 2012* -
## english

Main Idea: The big rivers in the center of the United States have a constant power that is greater than the human uses for the rivers. I need to provide 3 supporting details for main idea.

*asked on April 25, 2012* -
## math

How many possible outcomes are there for 15 coins tossed simultaneously?

*asked on April 17, 2011* -
## science

An abiotic factor that starts with c and the clue is soil type. So what is a soil type that starts with C?

*asked on April 4, 2011* -
## math

is -3+(-3) less than or greater than -6

*asked on February 24, 2011* -
## algebra 2

Which binomial is a factor of f(x) = x4 - 27x2 -14x + 120? (x-4) (x-2) (x + 5) (x + 6)

*asked on January 10, 2011* -
## algebra 2

Which binomial is a factor of f(x) = x4-27x2-14x + 120?

*asked on January 10, 2011* -
## physics

A jogger accelerates from rest to 2.7 m/s in 2.2 s. A car accelerates from 39.0 to 44.0 m/s also in 2.2 s. (a) Find the acceleration (magnitude only) of the jogger. (b) Determine the acceleration (magnitude only) of the car. (c) Does the car travel farther

*asked on September 7, 2010* -
## physics

An 18-year-old runner can complete a 10.0 km course with an average speed of 4.51 m/s. A 50-year-old runner can cover the same distance with an average speed of 4.31 m/s. How much later (in seconds) should the younger runner start in order to finish the

*asked on September 3, 2010* -
## Chemistry

What are the products of nitrogen dioxide and methane?

*asked on April 27, 2009* -
## science

explain how energy is stored in and released from atp

*asked on November 13, 2007* -
## Calculus

Find the scalar equation of a plane that is perpendicular to plane r=(-2,1,3)+s(0,1,1)+t(-1,0,3) and also intersects it along the line (x-3)/2=(y+1)/-3,z=1

*asked on July 29, 2014* -
## statistics

A management consultant has analysed a random sample of 40 large firms in order to investigate the mean annual salary of sales managers. She has constructed the following 90% confidence interval for the population mean annual salary: $45,382 to $48,618. In

*asked on November 17, 2013* -
## math

The principal of Valley Elementary School wants to divide each of the three fourth-grade classes into small same-size groups with at least 2 students in each. If the classes have 18, 24, and 36 students, respectively, what size groups are possible?

*asked on December 20, 2012* -
## Physics

A 140 g, 90.0 mph fastball comes across the plate very nearly horizontally and is batted at 90.0 mph at a 30.0 O angle (above the horizontal) toward center field. (a) Determine the impulse (in N.s) acting on the ball. (b) If the impact time is 0.00080 s,

*asked on August 3, 2012* -
## Physics

A 125 kg flatbottomed boat is floating along at 5.0 m/s, headed east. Sally Sue, standing at one end of the boat, starts to walk at 2.0 m/s, also to the east. If Sally’s mass is 65 kg, what is the speed of the boat as she walks along?

*asked on August 3, 2012* -
## Physics

The Hubble Space Telescope (HST) has recorded evidence of a black hole at the center of the M87 galaxy. Using Doppler data, it's been measured that matter is orbiting the center of this galaxy at an orbital speed of 7.5x10 5 m/s, out at a radius of 5.7x10

*asked on July 26, 2012* -
## Physics

A 90.0 kg block and a 40.0 kg block are connected by a rope that passes through two (frictionless, massless) pulleys as shown. When released, what is the acceleration of the larger block? What is the tension in the rope?

*asked on July 25, 2012* -
## Physics

Sally Sue is atop a 10.0 m high platform where she will drop an apple straight down. On the ground below, and 20.0 m (horizontally) away, Betty Lou will shoot an arrow at the apple. If Betty's arrow has a release speed of 25.0 m/s, at what angle must she

*asked on July 14, 2012* -
## algebra

find all the zeros of each function. 1. f(x)=2x^4-13x^3-34x^2+65x+120 2. f(x)=4x^4+19x^2-63

*asked on May 5, 2012* -
## Chemistry

0.200 moles of NaF are added to 1L 2.0 molar HF. What is the pH? a) 2.14 b) 6.70 c) 10.80 d) 3.00 e) 7.00

*asked on April 29, 2012* -
## differential equations

Solve the following equation explicitly by expanding up to order x5, the following 2nd order diff equation. y''(x) = (1 + x^2)*y(x) pls show working y =f(x)

*asked on November 29, 2011* -
## Math

graph each linear function. y= -x + 4 y= 2/3x + 1 y= 2x + 1 y = -1/2x + 3

*asked on April 24, 2011* -
## math

is 10^2 less thans or greater than -200?

*asked on February 24, 2011* -
## algebra

a public television station set a goal of $350,000 in pledges during a certain month. the total pledged was $525,000. What percent of the station's goal was reached?

*asked on October 9, 2010* -
## arithmetic

0.2 in extended form

*asked on September 22, 2010* -
## Chemistry

Explain open and closed system with respect to equilibrum.

*asked on May 5, 2009* -
## Chemistry

what effect does a catalyst have on.. a) energy of the reactants b) enthalpy change of the reaction

*asked on April 27, 2009* -
## World History

Why would people choose an extremist form of government(either ultraliberal or ultraconservative)to rule over them?

*asked on March 24, 2009* -
## World History

Please help i would highly appreciate it

*asked on March 23, 2009* -
## physics

what physics are involved in the 100 meter dash

*asked on October 9, 2007* -
## physics

What is the maximum velocity of a spring oscillator with a mass of 0.7 kg and a spring constant of 74 N/m that is released from rest at a position of x = 0.1 m?

*asked on April 3, 2016* -
## genetics

1) Which of the following is a characteristic of RNA splicing in Eurkaryotes? a) Exon/intron boundaries are typically characterized by a 5' GU splice junction and a 3' AG splice junction. b) After splicing occurs, the U1, U2, U5, U6 snRNP complex removes

*asked on February 5, 2016* -
## Algebra

The sum of two numbers is 83. The difference of the two numbers is 24. Find the two numbers.

*asked on January 24, 2016* -
## Algebra

The sum of two numbers is 83. The difference of the two numbers is 24. Find the two numbers.

*asked on January 24, 2016* -
## Calculus

State the cartesian equations of two lines that make angle of 60 degrees with the line r=(1,3)+s(1,1)

*asked on July 29, 2014* -
## statistics

Consider an upper-tail test of hypothesis for the difference in two population means. The sample data from the first population is: n = 50, x-bar = 110, s = 10. The sample data from the second population is: n = 75, x-bar = unknown, s = 11. We conclude the

*asked on November 17, 2013* -
## statistica

A management consultant has analysed a random sample of 40 large firms in order to investigate the mean annual salary of sales managers. She has constructed the following 90% confidence interval for the population mean annual salary: $45,382 to $48,618. In

*asked on November 17, 2013* -
## Chemistry

How many sulfate ions are there in 2.500 mL of 5.0 x 10-15 moles of Cr2(SO4)3?

*asked on September 22, 2013*

## Pages

**1**- 2