Questions asked by Miroslav Georgiev

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• The half-life of arsenic-81 is 33 seconds. Suppose you have 100 g - how much will remain undecayed after 12.5 days?
  
• I know this relates to moles, so how do I convert 4.77 g of lead (Pb) to atoms?
  
• Suppose I am trying to determine a compound that has 15.87% carbon (C), 2.15 % hydrogen (H), 18.5% nitrogen (N), & 63.41% oxygen (O) (n.b., this does not equal exactly 100%): what is the empirical formula of the compound?
  
• I am trying to determine a compound 80.48% carbon (C), 7.37% hydrogen (H), 9.39% nitrogen (N), 2.68% oxygen (O) - what is the empirical formula of the compound?
  
• Can you write a synthesis reaction with 3 reactants on one side with a single product on the other (e.g., A + B + C → ABC)?
  
• How would I add #{5n}/{4n^2-20n}# to #{5n}/{n-1}# (e.g., #{5n}/{4n^2-20n}+{5n}/{n-1}#)?
  
• How many moles of lead (II) hydroxide will be produced from 3.0 moles of lithium hydroxide assuming there is an excess of lead (II) sulfate?
  
• If you have 12 mol FeCl3 and 12 mol O2, which would be the limiting reactant? (The equation is 4 FeCl3 + 3 O2 → 2 Fe2O3 + 6 Cl2)
  
• What volume of solution is needed to make a 3.0 M solution containing 109.5 g of hydrochloric acid?
  
• What mass (in g) of NaCl is needed to prepare 1.5 L of a 3.0 M salt water solution?
  
• How many joules are in 230 Calories?
  
• If 1210.5 g of copper (II) chloride (CuCl2) reacts with 510.0 g aluminum metal (Al) to produce 525.0 g copper metal (Cu), what is the limiting reactant?
  
• If you have 381 g Cu and 1359 g AgNO3, how many grams of silver could be made?
  
• Assuming that you can only make 863 g Ag, what is the percent yield of Ag if you actually recover 1018 g Ag?
  
• What is the percent composition of nitrogen, #N#, in ammonium sulfide, #(NH_4)_2S#?
  
• The empirical formula for #CO_3# was found to have a molar mass of 120 g/mol. What is the molecular formula?
  
• What are three ways to increase the rate of dissolving of 30 g of a large chunk of salt (#NaCl#) into 250 mL of 20 degrees Celsius of #H_2O#?
  
• How do I factor #i^2-4t-21# completely?
  
• How do I factor #8x^3-1# completely?
  
• How do I factor #6x^2-7x-3# completely?
  
• How do I factor #x^3-2x^2-4x+8# completely?
  
• How do I simplify #(5x^2)(2x^5)#?
  
• How do I simplify #(-2c^3)^2#?
  
• How do I simplify #(t^3)(t^(n-3))#?
  
• How do I simplify #(10*2^6)/(8*2^(-2))#?
  
• What is #(sqrt(2x+4))^2#?
  
• What is the domain of #f(g(x))# if #f(x)=x^2-4# and #g(x)=sqrt(2x+4)# ?
  
• How do I simplify #(x^2-25)/(x^2+7x+10)#?
  
• How do I simplify #(x^2-5x+6)/(x^2-4)*(x^2+3x+2)/(x^2-2x-3)#?
  
• How do I simplify #(2x)/(x+5)÷(6x^2)/(2x+10)#?
  
• How do I simplify #(2x)/(x-3)-(x)/(x+3)#?
  
• If a car is travelling at 21.8 kilometers per hour, how fast is that in millimeters per second?
  
• If I have a circle with with an arc length of 31 in. and a radius of 12 in., then what is the angle in radians?
  
• A satellite in a circular orbit 1250 kilometers above Earth makes one complete revolution every 110 minutes. What is its linear speed? (Assume that Earth is a sphere of radius 6400 kilometers.)
  
• How would you calculate the speed (in #m/s#) of a skateboarder who accelerates from rest for 4 seconds down a ramp at an acceleration of #3 m/s^2#?
  
• The length of the barrel of a primitive blowgun is 1.5 m. Upon leaving the barrel, a dart has a speed of 14 m/s. Assuming that the dart is uniformly accelerated, how long does it take for the dart to travel the length of the barrel?
  
• A Top Fuel dragster accelerates uniformly from rest to a speed of 497.52 kph in a time of 4.96 seconds. How long does it take the car to reach 100 m/s?
  
• A car driving at 41m/s hits the brakes and comes to a stop in 4.8 seconds. What was the car's acceleration during this stop?
  
• A car driving at 41m/s hits the brakes and comes to a stop in 4.8 seconds. How fast was it going after 2.4 seconds?
  
• A girl stands on top of the Golden Gate Bridge and drops a penny straight down. How long does it take the penny to fall the 228m to the San Francisco Bay? [FULL QUESTION in the answer]
  
• A student drops his textbook out of a window in a tall building. If it took 1.51 seconds for the book to hit the ground, how high above the ground is the window? What is the book' maximum speed during flight? At what time does this occur?
  
• A student drops his textbook out of a window in a tall building. How high above the ground is the book when it is falling at a speed of 438 cm/s?
  
• Boy Scouts are firing model rockets in a field. One boy used a radar gun to determine his rocket had a lift-off velocity of 34 m/s. How long did it take for the rocket to return to the ground? Assume the rocket went straight up and came straight down.
  
• Boy Scouts are firing model rockets in a field. One boy used a radar gun to determine his rocket had a lift-off velocity of 34 m/s. How high did the rocket travel?
  
• Boy Scouts are firing model rockets in a field. One boy used a radar gun to determine his rocket had a lift-off velocity of 34 m/s. When the rocket was traveling at 17m/s, how far was it from its highest point?
  
• A man stands on a crane and throws a water balloon down at at 21 m/s. He finds that it takes 2.4s for the balloon to hit the ground. How fast is the water balloon travelling when it hits the ground?
  
• A man stands on a crane and throws a water balloon down at at 21 m/s. He finds that it takes 2.4s for the balloon to hit the ground. What is its velocity after 1.14 seconds have passed?
  
• A man stands on a crane and throws a water balloon down at at 21 m/s. He finds that it takes 2.4s for the balloon to hit the ground. What is its height one second before it hits the ground?
  
• A man stands on a crane and throws a water balloon down at at 21 m/s. He finds that it takes 2.4s for the balloon to hit the ground. How far has the balloon fallen when it is travelling 40.3 m/s?
  
• If a distance-time graph (starting at (0,10) and ending at (10,0) has a negative linear trend, then what would the velocity-time and acceleration-time graphs look like?
  
• If a velocity-time graph (starting at (0,0) and ending at (10,10) has a positive linear trend, then what would the distance-time and acceleration-time graphs look like?
  
• If a acceleration-time graph has a static trend, i.e., neither moving up or down (starting at (0,50) and (for the purposes of the graph) ending at (10,50), then what would the velocity-time and distance-time graphs look like?
  
• If a velocity-time graph has a static trend, i.e., neither moving up or down (starting at (0,50) and (for the purposes of the graph) ending at (10,50), then what would the acceleration-time and distance-time graphs look like?
  
• If a distance-time graph has a negative parabolic curve trend (starting at (0,100) and ending at (10,0), then what would the velocity-time and acceleration-time graphs look like?
  
• A man stands on a crane and throws a water balloon down at at 21 m/s. He finds that it takes 2.4s for the balloon to hit the ground. What is its height one second before it hits the ground?
  
• How do you convert #9.8 xx 10^3# #mu"m/ms"# to #"m/s"#?
  
• A man walks 98m south. He stops and drops a letter into the mailbox, turns and walks 28m to the north. This trip took 4 minutes. What was the man's average speed for the walk?
  
• A car drives straight off the edge of a cliff that is 58 m high. The police at the scene of the accident note that the point of impact is 0.136 km from the base of the cliff. How long did it take to hit the ground?
  
• A car drives straight off the edge of a cliff that is 58 m high. The police at the scene of the accident note that the point of impact is 0.136 km from the base of the cliff. How fast was the car traveling when it went over the cliff?
  
• A car drives straight off the edge of a cliff that is 58 m high. The police at the scene of the accident note that the point of impact is 0.136 km from the base of the cliff. How far from the cliff was the car after 1.5s?
  
• A car drives straight off the edge of a cliff that is 58 m high. The police at the scene of the accident note that the point of impact is 0.136 km from the base of the cliff. How far down had the car fallen after 1.5s?
  
• A car drives straight off the edge of a cliff that is 58 m high. The police at the scene of the accident note that the point of impact is 0.136 km from the base of the cliff. What is the car's final velocity?
  
• A ball rolling at a constant speed falls off of a table and lands 98 cm from the bottom of the table, 0.49s after rolling off of the edge. How fast was the ball rolling on the table? How tall is the table? How far from the table is the ball after 0.061s?
  
• A ball rolling at a constant speed falls off of a table and lands 98 cm from the bottom of the table, 0.49s after rolling off of the edge. What is the ball's velocity when it hits the ground?
  
• An arrow is shot horizontally off of a tower that is 33m high. The arrow lands on the ground 31m from the base of the tower. How long did it take to hit the ground? What was the arrow's original velocity? How far from the tower was the arrow after 0.13s?
  
• An arrow is shot horizontally off of a tower that is 33m high. The arrow lands on the ground 31m from the base of the tower. How high above the ground was the arrow after 0.13s? What is the arrow's final velocity?
  
• When chasing a hare along a flat stretch of ground, a greyhound leaps into the air at a speed of 24.48 km/hr, at an angle of 34.6°. How long is the dog in the air? How far does the dog jump? How high does the dog get?
  
• A girl stands on top of the Golden Gate Bridge and throws a penny at a speed of 94.32km/hr at an angle of -68.8°. How long does it take the penny to fall the 224m to the San Francisco Bay?
  
• The girl's brother stands at the edge of the Golden Gate Bridge and throws a penny upwards at 29 m/s at an angle of 34°. How long does it take the penny to fall to the water, 227m below? How far from the base of the bridge does the penny hit the water?
  
• An archer shoots an arrow at an angle of 30 degrees from a height of 1.4m. If it took 1.6 seconds for the arrow to hit the target, which is 1.4m tall, what was the arrow's initial speed? How far away was the target?
  
• The punter stands on the 22 yard (roughly a meter) line to the left of the 50 yard line and the ball is kicked with an initial velocity of 25.3 m/s at an angle of 58.5° above the ground. What is the hang time of the football?
  
• The punter stands on the 22 yard (roughly a meter) line to the left of the 50 yard line and the ball is kicked with an initial velocity of 25.3 m/s at an angle of 58.5° above the ground. Where does the ball land?
  
• The punter stands on the 22 yard (roughly a meter) line to the left of the 50 yard line and the ball is kicked with an initial velocity of 25.3 m/s at an angle of 58.5° above the ground. How far from the punter is the football when it's at its max height?
  
• The punter stands on the 22 yard (roughly a meter) line to the left of the 50 yard line and the ball is kicked with an initial velocity of 25.3 m/s at an angle of 58.5° above the ground. How high does the punt go?
  
• Is this a true statement: If an object is weightless, then no gravity is acting upon it?
  
• A boy with a mass of 34 kg hangs straight down from the monkey bars with two arms. What is the tension in each arm (in Newtons)?
  
• An adult lion standing in Las Vegas has a mass of 210 kg. How much force is exerted downward on the lion by gravity (i.e., the weight)? How much normal force pushes up on the lion?
  
• A man with a mass of 120 kg sits on the lion's back. How much force is exerted downward on the ground by the lion with the man on his back? How much downward force does the lion feel on his back from the man?
  
• A man with a mass of 120 kg sits on the lion's back. How much normal force does the ground exerts upwards on the lion? How much normal force does the lion exerts upwards on the man? What is the net force acting on the lion?
  
• A 41 kg rock accidentally breaks loose from the edge of a cliff and falls straight down. The magnitude of the air resistance that opposes its downward motion is 260 N. What is the magnitude of the acceleration of the rock?
  
• A 41 kg rock accidentally breaks loose from the edge of a cliff and falls straight down. The magnitude of the air resistance that opposes its downward motion is 260 N. How much air resistance would cause the rock to fall at a constant speed?
  
• A man stands on a scale while riding an elevator. The mass of the man is 84kg. What will the scale say when the elevator is stopped on the ground floor? What will the scale say when the elevator is ascending at 4m/s²?
  
• A man stands on a scale while riding an elevator. The mass of the man is 84kg. What will the scale say if the elevator is descending at the same rate as gravity? What will the scale say if the elevator is ascending at a constant speed of 15m/s?
  
• A man stands on a scale while riding an elevator. The mass of the man is 84kg. What is the elevator's acceleration if the scale reads 1025 Newtons?
  
• A 50.0 kg crate rests on a level floor at a shipping dock. The coefficients of static and kinetic friction are 0.750 and 0.430, respectively. What horizontal pushing force is required to just start the crate moving?
  
• A 50.0 kg crate rests on a level floor at a shipping dock. The coefficients of static and kinetic friction are 0.750 and 0.430, respectively. What horizontal pushing force is required to slide the crate across the dock at a constant speed?
  
• How would you calculate the acceleration if you push with a 20 N horizontal force on a 3 kg block on a horizontal friction-free air table? What is the acceleration if the friction force is 4 N?
  
• A NASCAR of mass 1400kg has broken down on pit lane. The coefficient of static friction between the tires and the road is 0.55. How hard would the crew have to push to get the car moving?
  
• A NASCAR of mass 1400kg has broken down on pit lane. The coefficient of static friction between the tires and the road is 0.55. If the crew pushes with a force of 8046 N, what will the magnitude of the car's acceleration be?
  
• A NASCAR of mass 1400kg has broken down on pit lane. The coefficient of static friction between the tires and the road is 0.55. How hard would the crew have to push to accelerate the car at 3.60m/s²?
  
• Given vectors #u##=##<4,1># & #v##=##<1,3>#, how would I determine the quantity #3u#*#-2v#?
  
• How would I use the dot product of #u# if #u##=##5i##+##2j#?
  
• How would I find the angle between vectors #u# & #v# if #u##=##i#+#4j# & #v##=##-i#+#2j#?
  
• How do you find the absolute value of the complex number #-4+i#?
  
• How do you find the trigonometric form of the complex number #3##sqrt3##+##3i#?
  
• How would I perform the operation #14(cos 63° + isin 63°)##/##20(cos 15° + isin 15°)#? Make sure to leave the result in trigonometric form.
  
• How do I use DeMoivre's theorem to find #(-3+3i)^3#?
  
• How would I find the standard form of the complex number #9(cos((7pi)/6)=isin((7pi)/6))#?
  
• The mass of each car is 600kg, 970kg, 230kg, 810kg, 660kg. The force of friction on each car is 1980N, 3201N, 759N, 2673N, 2178N respectively. If the train is traveling at a constant velocity, what is the force supplied by the locomotive?
  
• The mass of each car is 600kg, 970kg, 230kg, 810kg, 660kg. The force of friction on each car is 1980N, 3201N, 759N, 2673N, 2178N respectively. What is the magnitude of the upward forces on the 5th car?
  
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