Help me with calculations!

[cookies]

I need someone to check my work and see if it did it right or not. I skip some of them because I do not know them, and I hope you guys can help me. This is my final study guide for my final test in physical science. Please help me out!

 

 

 

Calulating Density

 

Density = Mass/Volume

 

1. What is the density of carbon dioxide gas if 0.196g occupies a volume of 100 mL?

ANSWER: 0.00196 g/mL

 

2. A block of wood 3.0 cm on each side has a mass of 27 g. What is the density of this block

ANSWER: 1 g/cm^3

 

3. An irregularly shaped stone was lowered into a graduated cylinder holding a volume of water equal to 2.0 mL. The height of the water rose 7.0 mL. If the mass of the stone was 25g, what was its density?

ANSWER: 5 g/mL^3

 

4. A 10.0 CM^3 sample of copper has a mass of 89.6 g. What is the density of copper?

ANSWER: 8.96 g/cm^3

 

5. Silver has a density of 10.5g/CM^3 and gold has a density of 19.3 g/CM^3 . Which would have a greater mass, 5cm^3 of silver or 5cm^3 of gold?

ANSWER: Gold

 

6. Five mL of ethanol has a mass of 3.9g, and 5.0 mL of benzene has a mass of 4.4g. Which liquid is denser?

ANSWER: Benzene.

 

7. A sample of iron has the demensions of 2 cm x 3 cm x 2cm. If the mass of this rectangular-shaped object is 94g, what is the density of iron?

ANSWER: 7.83 g/cm^3

 

Acceleration Calculations

 

Acceleration = Final velocity - initial velocity/time

 

Initial Velocity Final Velocity Time Acceleration

1. 0 km/hr 24 km/hr 3s = 8 km/hr/s

2. 0 m/s 35 m/s 5s = 7 m/s/s

3. 20 km/hr 60 km/hr 10s = 4 km/hr/s

4. 50 m/s 150 m/s 5s = 20 m/s/s

5. 25 km/hr 1200 km/hr 2mins = 587.5 km/hr/m

 

6. A car accelerates from a standstill to 6 km/hr in 10 second. What is its acceleration?

ANSWER: 0.6 km/hr/s

 

7. Acar accelerates from 25 km/hr to 55 km/hr in 30 seconds. What is its acceleration?

ANSWER: 1 km/hr/s

 

8. A train is accelerating at a rate of 2 km/hr/s. If its inital velocity is 20 km/hr, what is its velocity after 30 seconds?

ANSWER: 80 km/hr

 

9. A runner achieves a velocity of 11.1 m/s 9s after he begins. What is his acceleration? What is his distance did he cover?

ANSWER: 1.23 m/s/s, distance is 49.95 m

 

Calculating Power

 

Power = Work/time

 

1. A set of pulleys is used to lift a piano weighing 1000 newtons. The piano lifted 3 meters in 60 seconds. How much power is used?

ANSWER: 500W

 

2. How much power is used if a force of 35 newtons is used to push a box a distance of 10 meters in 5 seconds?

ANSWER: 70W

 

3. What is the power if a kitchen blender if it can perform 3750 joules of work in 15 seconds?

ANSWER: 250W

 

4. How much work is done using a 500W microwave oven for 5 minutes?

ANSWER: 2500J

 

5. How much work is done using a 60W light bulb for 1 hour?

ANSWER: 216,000J

 

Determining Speed (Velocity)

 

Speed = Distance/Time Velocity = Distance/time

 

1. What is the velocity of a car that traveled a total of 75 kilometers north in 1.5 hours?

ANSWER: 50 km/hr

 

2. What is the velocity of a plane that traveled 3000 miles from New York to California in 5 hours?

ANSWER: 600 m/hr

 

3. John took 45 minutes to bicycle to his grandmother's house, a total of four kilometers. What was his velocity in km/hr?

ANSWER: 11.25 km/hr

 

4. It took 3.5 hours for a train to travel the distance between two cities at a velocity of 120 miles/hr. How many miles lie between the two cities?

ANSWER: 420 miles

 

5. How long would it take for a car tp travel a distance of 200 kilometers if it is travelingat a velocity of 55 km/hr?

ANSWER: 3.63 hour

 

6. A car traveling at 100 km/hr. How many hours will it take to cover a distance of 750 km?

ANSWER: 7.5 hours

 

7. A plane traveled for about 2.5 hours at a velocity of 1200 km/hr. What distance did it travel?

ANSWER: 300 km

 

8. A girl is pedaling her bicycle at a velocity of 0.10 km/min. How far will she travel in two hours?

ANSWER: .20 km

 

Force and Acceleration

 

Force = Mass x Acceleration

 

1. With what force will a car hit a tree if the car has a mass of 3000 kg and it is accelerating at a rate of 2 m/s^2

ANSWER: 6000N

 

2. A 10 kg bowling ball would require what force to accelerate it down an alleyway at a rate of 3 m/s^2

ANSWER: 30N

 

3. What is the mass of a falling rock if it hits the ground with a force of 147 newtons?

ANSWER: Help!

 

4. What is the acceleration of a softball if it has a mass of 0.50 kg and hits the catcher's glove with a force of 25 newtons?

ANSWER: 0.4 m/s

 

5. What is the mass of a truck if it is accelerating at a rate of 5 m/s^2 and hits a parked car with a froce of 14000 newtons?

ANSWER: 2800 kg

 

Heat and Phase Changes

 

For freezing and melting

Heat = (mass in grams) x (heat of fusion)

 

For boiling and condensation

Heat = (mass in grams) x (heat of vaporization)

 

The heat of fusion of water = 340 j/g

The heat of vaporization of water = 2300 j/g

 

1. How many joules of heat are necessary to melt 500 g of ice at its freezing point?

ANSWER: 170,000J

 

2. How many kilojoules is this?

ANSWER: HELP!

 

3. How much heat is necessary to vaporize 500 g of water at its boiling point?

ANSWER: 115,000J

 

4. If 5,100 joules of heat are given off when a sample of water freezes, what is the mass of the water?

ANSWER: 15g

 

5. If 57,500 joules of heat are given off when a sample of steam condenses, what is the mass of the steam?

ANSWER: 25g

 

Calculating Work

 

Work = Force x Distance

 

1. A book weighing 1 newton is lefted 2 meters. How much work was done?

ANSWER: 2J

 

2. A force of 15 newton is used to push a box along the floor a distance of 3 meters. How much work was done?

ANSWER: 45J

 

3. It took 50 Joules to push a chair 5 meters across the floor. With that force was the chair pushed?

ANSWER: 10N

 

4. A force of 100 newtons was necessaryto lift a rock. A total of 150 joules of work was done. How far was the rock lifted?

ANSWER: 1.5 meters

 

5. It took 500 newtons of force to push a car 4 meters. How much work was done?

ANSWER: 2000J

 

6. A young man exerted a force of 9000 newtons on a stalled car but was unable to move it. How much work was done?

ANSWER: No work was done there.

 

Potential and Kinetic Energy

 

Potential energy = weight x height

 

Kinetic Energy = 1/2 mass x velocity^2

 

1. What is the potential energy of a rock that weighs 100 newtons that is sitting on top of a hill 300 meters high?

ANSWER: 30,000J

 

2. What os the kinetic energy of a bicycle with a mass of 14 kg traveling at a velocity of 3 m/s?

ANSWER: 63J

 

3. A flower pot weighing 3 newtons is sitting on a windowsill 30 mets from the ground. Is the energy of the flower pot potential or kinetic? How much joules is this?

ANSWER: Potential, 90J

 

4. When the flower pot in problem 3 is only 10 meter from the ground, what is the potential energy?

ANSWER: 30J

 

5. How much of the total energy in problem 3 and 4 has been transformed to kinetic energy?

ANSWER: HELP!

 

6. A 1200 kg automobile is traveling at a velocity of 100 m/s. Is its energy potential or kinetic? How much energy does it possess?

ANSWER: Kinetic, 6,000,000J

 

Physical vs. Chemical Properties

 

1. Red color - Physical property

2. density - physical

3. flammability - physical

4. solubility - Chemical property

5. reacts with acid to from hydrogen - Chemical property

6. supports combustions - Chemical property

7. bitter taste - Phyiscal property

8. melting point - physical

9. reacts with water to form gas - Chemical Property

10. reacts with a base to form water - Chemical Property

11. hardness - Physical property

12. boiling point - physical property

13. can neutralize a base - chemical property

 

Phyiscal vs chemical change

 

1. Sodium hydroxide dissolves in water - Chemical

2. Hydrochloric acid reacts with sodium hydroxide to produce a salt, water, and heat - Chemical

3. A pellet of sodium is sliced in two - Physical

4. Water is heated and changed to steam - Physical

5. Potassium chlorate decomposes to potassium chloride and oxygen gas - Chemical

6. Iron rusts - Chemical

7. ice melts - physical

8. Acid on limestone produces carbon dioxide gas - chemical

9. milk sours - chemical

10. wood rots - physical

 

Substances vs. Mixture

 

1. sodium - S

2. water - S

3. Soil - M

4. Coffee - M

5. Oxygen - S

6. Alcohol - M

7. Carbon dioxide - S

8. Cake batter - M

9. Air - M

10. Soup - M

11. Iron - S

12. Salt water - M

13. ice cream - M

14. nitrogen - S

15. eggs - M

16. blood - M

17. table salt - S

18. nail polish - M

19. milk - M

20. Cola - M

[Klaynos]

As discussed, 1,2,3 are wrong

[cookies]

this is tricky.. number3

[Callipygous]

i tried to go through and clean up the units confusion with him, but its been a few years and i dont remember anything about, for example, power units. could someone double check?

[cookies]

yeah thanks for helping me still need help with the last 3 sections

[Cap'n Refsmmat]

6. Iron rusts - Physical

When iron rusts, it does this:

2Fe + 3O₂ -> 2Fe₂O₃

[cookies]

oh dear! i belieave that is M lol

 

thats the only 1 i have wrong?

[Cap'n Refsmmat]

Check substances vs. mixture 7, 9, and 17.

[cookies]

so air is a mixture huh? .. i dun see how table salt is a substance.. can you explain? and can you please check the physical and chemical property part

[Cap'n Refsmmat]

Table salt is NaCl.

 

Recheck the properties part. Remember that when a material changes state (solid -> liquid, etc.) it is not a chemical change but a physical one.

[MolotovCocktail]

so air is a mixture huh? .. i dun see how table salt is a substance.. can you explain? and can you please check the physical and chemical property part

 

Well, just about anything can be a substance. Air is a mixture of all different types of gases, and on Earth it is mostly Nitrogen and Oxygen.

 

About physical and chemical properties:

 

#2, 4, 8 and 12 are wrong.

[cookies]

there we go, i fixed all i think were wrong.. please check the last 3 sections again for me

[Rasori]

Table Salt question: I understand table salt is NaCl, but don't most table salts have other additives for freshness which technically makes them a mixture?

 

Similar question on 1: physical vs chemical change. I'm not sure of this, but I think dissolving is a physical change, as it's not forming bonds with the water, ie it's still its own entity. Don't listen to me though, wait for the people who respond to me lol.

[Cap'n Refsmmat]

http://en.wikipedia.org/wiki/Solvation

 

Oftentimes (for strong electrolytes) the solute breaks apart into ions and spreads into the solvent. Or so they tell me.

[gregwaters2001]

Hello I am new at this and I was trying to find the calculations to the questions that were posted 1-7