Physics Semester II Final Study Guide

Power Work Energy Conservation of energy Simple machines Thermodynamics

Waves Sound Light Mirrors Lenses Circuits

Always bring your buddy! Know all of your formulas Be very careful with your units Skim each of these topics in the textbook Do additional practice problems Solve these practice problems over and over until you could do them in your sleep. Get plenty of rest and eat healthy. If you are stuck, come to office hours/tutoring and try to find videos that help.

Work (page 258)1. What are the units of Work? 2. What are the equations for Work?3. A student lifts a box of books that weighs 185 N. The box is lifted 0.800 m. How much

work does the student do on the box? 148 J4. Two students together exert a force of 825 N in pushing a car 35 m.

a. How much work do they do on the car? 2.9x10^4 Jb. If the force were doubled, how much work would they do pushing the car the

same distance? 5.8 x 10^4 J5. A 0.180 kg ball falls 2.5 m. How much work does the force of gravity do on the ball? (2

steps) 4.4 J6. How much work does the force of gravity do when a 25 N object falls a distance of 3.5

m? 88 J7. A rope is used to pull a metal box 15.0 m across the floor. The rope is held at an angle of

46 ° with the floor and a force of 628 N is used. How much work does the force on the rope do? (Hint: use W=Fdcos θ) 6.54x10^3 J

8. A student holds a book 3 m off the ground. If the mass of the book is 2 kg, what is the work done on the book? 58.8 J

9. A pencil held in the air has 14.7 J of potential energy. How much work was done to lift the pencil to its position? ???

10. Ms. Casciato’s pet monkey lifts a stack of books into the air and does 50 joules of work. How much potential energy does the stack of books have?

11. A worker lifts a crate from one floor to the next in a warehouse. A force of 48 N is exerted through a distance of 40 m on the rope of a pulley system. How much work is done? 1920 J

12. A 50-kg student runs up a flight of stairs that is 6 m high. How much work is done? 6300J 13. How much work is required to lift a 2.5 kg object to a height of 6.0 meters? 147 J

https://www.youtube.com/watch?v=6jh0kHdv1gQ14. A soccer ball experiences a change in energy of 40 J along its path of motion. What was

the work done?

Power (page 263)1. What are the units of power?2. What are the equations for power? 3. Power is the ____ at which energy is _____.4. Which light bulb is more powerful, one that can transform 100 Joules per second, or one

that transform 60 Joules per second?5. Which motor is more powerful, one that can lift a certain weight 1 meter in 2 seconds, or

one that can lift the same weight 1 meter in 5 seconds?6. What is the power rating of a heater that can transform 5000 J of energy from electric to

heat every 12 seconds?7. How much energy is transformed from electric to light/thermal by a 75 W light bulb in 23

seconds?8. A woman pushes a piano five meters with a force of three Newtons in five seconds, how

much power did it take? 3 watts9. (1 HP = 745.7 Watts) A weightlifter raises a barbell of mass 100 kg from the floor to over

his head (2.5 meters) in 2 seconds. What is his average power input? Give your answer in both Watts and horsepower. 1250 W, 1.7 HP

10. If a ride at Disneyworld goes from rest to 27 m/s in 2.8 seconds and the mass of the ride and riders together is 5000 kg (true data!), what is the average power required to do this? Give your answer in both Watts and horsepower. 650900 W, 874 HP

11. A 100-Watt light bulb has an average life of 2000 hours. How much energy does it consume over its lifetime? Give your answer in Joules and kW-hours. 7.2 x 108 J, 200kW·h

12. A 2-HP winch is used to raise loads of bricks up a 30-meter building. If the bricks need to get to the top of the building in 2 minutes, what is the maximum allowable mass of a load of bricks? 596 kg

13. Nick spends 20 minutes ironing shirts with his 1,800-watt iron. How many joules of energy were used by the iron? (Hint: convert time to seconds) 2, 160, 000 J

Energy & Conservation of energy1. What unit is used to measure energy?2. What are the equations for energy?3. A 2.0 kg mass is moving with a speed of 3.0 m/s. What is the kinetic energy of the mass?

9.0 J4. Three objects move with a velocity of 1 m/s.

What is the total kinetic energy of the system? 5 J5. What is the kinetic energy of an object with a mass of 10 kg traveling at a speed of 10

meters per second? Assume no other forces act upon the object. 500 J6. What is the kinetic energy of a 2 kg toy car moving at a velocity of 5 m/s? 25 J7. A 50 kg firefighter is on a ladder 10 meters above the ground. When the firefighter

descends to 5 meters above the ground, the firefighter’s gravitational potential energy will decrease by __? 2450 J

8. A hydraulic lift used at an automotive repair shop raises a 1000 kg car two meters off the ground. What is the potential energy given to the car? 19,600 J

9. A high diver steps off a diving platform that is 10 meters above the water. If no air resistance is present, during the fall there will be a decrease in the diver’s ____? GPE

10. Starting from rest, a 2 kg block of wood slides a distance of two meters down a frictionless slope, as shown.

What is the approximate kinetic energy of the wooden block at the bottom of the slope? _______ . What is the approximate kinetic energy at the top? ______ 20 J & 0 J

11. In collisions between two objects, kinetic energy is conserved only _______. IN ELASTIC COLLISIONS

12. What is the kinetic energy of a 4 kg ball that is rolling at 2 meters per second? 8 J13. The potential energy of an apple is 6.00 joules. The apple is 3.00 meters high. What is the

mass of the apple? 0.204 kg or 204 grams14. Determine the amount of potential energy of a 5 N book that is moved to three different

shelves on a bookcase. The height of each shelf is 1.0 meter, 1.5 meters, and 2.0 meters. 5J, 7.5 J, 10 J, respectively.

15. A machine lifted two objects. One object has a mass of 2 kg, and was lifted at a speed of 2 m/s. The other had a mass of 4 kg and was lifted at a rate of 3 m/s.

a. Which object had more kinetic energy while it was being lifted? The 4 kgb. Which object had more potential energy when it was lifted to a distance of 10

meters? (Remember gravity = 9.8 m/s^2) The 4 kg 16. The work done to lift a book into the air is 37.5 J what is the potential energy of the

book?17. Wasted energy is dissipated as ______. 18. If the efficiency of a machine is low, then _________________19. A 74 kg student, starting from rest, slides down an 11.8-meter high water slide. How

fast is he going at the bottom of the slide? 15.21 m/s20. Ms. Casciato’s pet monkey lifts a stack of books into the air and does

50 joules of work. How much potential energy does the stack of books have? ???

21. Calculate the potential energy, kinetic energy, mechanical energy, velocity, and height of the skater at the various locations.

22. At a given point on a slope, an object has a potential energy of 250 J and a kinetic energy of 300 J what is the total energy?

23. Using the picture below to answer the following

questions. a. What is the potential energy half way down the hill? 294000 Jb. What is the kinetic energy half way down the hill? 294000 Jc. What is the potential energy 100 m from the ground? 196000 Jd. What is the kinetic energy 100 m from the ground? 392000 J

Simple machines1. A machine with a mechanical advantage of 10 is used to produce an output force of 250

Newtons. What input force is applied to this machine?2. If the efficiency of a machine is low, then _________________3. Which two pictures show the most efficient way to lift the heavy objects?

Choose the correct word from box one to fill in blank 1. Choose the correct word from box 2 to fill in blank 2. Choose the correct word from box 3 to fill in blank 3.

4. Picture A shows a _______ system that ________ the amount of work needed. The most important point to this system is that it ________ the amount of mass being lifted.

5.5.5.5.

Picture B shows a _______system that _____ the amount of work needed. The most important point of this system is that the direction of the force applied can be ________.

Box 1 Box 2 Box 3PulleyLever

Doesn’t changeIncreasesDecreases

ChangedIgnored

6. A cell phone charger uses 4.83 joules per second when plugged into an outlet, but only 1.31 joules per second actually goes into the cell phone battery. The remaining joules are lost as heat. That’s why the battery feels warm after it has been charging for a while. How efficient is the charger? 27%

7. A sledgehammer is used to drive a wedge into a log to split it. When the wedge is driven 0.20 m into the log, the log is separated a distance of 5.0 cm. A force of 1.7 x10^4 N is needed to split the log, and the sledgehammer exerts a force of 1.1*10^4 N. What is the IMA of the wedge? 4.0

Thermodynamics1. Understand how heat flows by conduction and how it flows by radiation.2. Convert the following Kelvin temperatures to Celsius:

a. 115 Kb. 172 K

3. A cup of water at 40 °C and a cup of water at 5°C are left on a table. What would the graph look like that shows the temperature of the two cups of water as time passes?

4. An engine has an input of heat energy of 10,750 J and does 2420 J of work. What is the heat loss? 8330 J

5. A proposed ideal heat engine would run with a high temperature reservoir at 800 kelvin and a low temperature reservoir at 300 kelvin. When the engine is running, it extracts 400 J of energy from the hot reservoir and does 250 J of work each minute. How much energy is expelled to the low temperature reservoir each minute? 150 J

Box 1 Box 2 Box 3PulleyLever

Doesn’t changeIncreasesDecreases

DoublesCuts in half

6. The pressure of a gas inside a closed, rigid container will increase when the gas temperature increases. Why does the pressure of the gas increase?

7. When does the order of a system increase?8. Use the chart below to answer the following questions.

a. A 0.5 kg piece of aluminum increases its temperature 7 °C when heat energy is added. How much heat energy produced this change in temperature? 3150 J

b. A volume of water has a mass of 0.5 kg. If the temperature of this amount of water was raised by 7°C, how much heat energy is produced? 14644 J

c. When 1500 J of energy is lost from a 0.12 kg object, the temperature decreases from 45°C to 40°C. What is the specific heat of this object? Of what material is the object made? 2500 j/kg °C - Wood

9. A gas balloon absorbs 75 J of heat. The balloon expands but stays at the same temperature. How much work did the balloon do in expanding? (75 J)

10. How many times would you have to drop a 0.50 kg bag of lead shot from a height of 1.5 m to heat the shot my 1.0°C? 9 drops

Waves1. What is periodic motion and simple harmonic motion?2. Draw a wave and label all the important information.3. What is the period of a wave and how do you find it?4. How much force is necessary to stretch a spring 0.25 m when the spring constant is 95

N/m? 24 N5. What is the period on Earth of a pendulum with a length of 1.0 m? 2.0 s6. How long must a pendulum be on the moon, where g = 1.6 m/s^2, to have a period of

2.0s? 0.16 m7. What is a wave pulse?8. What is a periodic wave?9. What are a transverse and a longitudinal wave?10. How do you measure wavelength, period, and frequency?11. A hiker shouts toward a vertical cliff 465 m away. The echo is heard 2.75 s later.

a. What is the speed of sound of the hiker’s voice in air? 338 m/sb. The wavelength of the sound is 0.750 m. What is its frequency? 451 Hzc. What is the period of the wave? 2.22x10^-3 s

12. If you want to increase the wavelength of a rope, should you shake it at a higher or lower frequency?

13. The speed of a transverse wave in a string is 15.0 m/s. If a source produces a disturbance that has a frequency of 6.00 Hz, what is its wavelength? 2.50 m

14. A periodic longitudinal wave that has a frequency of 20.0 Hz travels along a coil spring. If the distance between successive compressions is 0.600 m, what is the speed of the wave? 12.0 m/s

15. What is a node and antinode? Be able to recognize them visually.16. How can wind cause a bridge to collapse? (Looking for a physics term here)

Sound1. What type of wave is sound moving through air?2. What type of wave is a radio wave?3. What is the Doppler effect? How does it affect sound?4. What unit is used to measure sound level?5. Find the wavelength in air at 20 °C of an 18-Hz sound wave, which is one of the lowest

frequencies that is detectable by the human ear. 19 m6. Find the frequency of a sound wave moving through iron at 25°C7. A sound wave is produced in a metal cylinder by striking one end. What occurs as the

wave travels along the cylinder?8. A sound wave traveling through a solid material has a frequency of 500 Hz. The

wavelength of the sound wave is 2 meters. What is the speed of sound in the material? 100m/s

9. A tuning fork is used to produce sound waves with a frequency of 440 Hz. The waves travel through the air at 344 m/s. What is the wavelength of the sound waves? 0.78 m

10. Why would astronauts on the moon not be able to hear a landslide?11. Sound waves cannot carry energy through ____?12. An engineer in a moving train blows the train’s horn. The train is moving away from a

person standing on the ground. Compared to the frequency of the sound that the engineer hears, the person standing on the ground hears a sound with _______ frequency?

13. If you shout across a canyon and hear the echo 0.80 s later, how wide is the canyon? 140m

14. A giant gorilla roars at 262 Hz. How fast would the gorilla have to go to raise the pitch to 271 Hz? Use 343 m/s as the speed of sound. 11.4 m/s

15. A submarine is moving toward another submarine at 9.20 m/s. It emits a 3.50 – MHz ultrasound. What frequency would the second sub, at rest, detect? The speed of sound in water is 1482 m/s. (Hint: Doppler) 3.52 MHz

16. How do you find the velocity of sound waves if in different temperatures of air? (Check your buddy)

17. If you shout across a canyon in 32 ° air, and you hear an echo 0.80 seconds later, how wide is the canyon? 139.95 m

18. A trumpet player sounds a C note at 524 Hz while traveling in a convertible at 24.6 m/s. If the car is coming toward you, what frequency would you hear? Assume the temperature is 20 °C . 564.49 Hz

19. A trumpet player sounds a C note at 524 Hz while traveling in a convertible at 24.6 m/s. If the car is moving away you, what frequency would you hear? Assume the temperature is 20 °C . 489 Hz

Light1. Objects appear different in size and shape in a container of water do to _________ of the

light rays.2. What is the speed of light?3. How does a polarized lens work?4. What is the frequency of oxygen’s spectral line if its wavelength is 513 nm? 5.85x10^14

Hz5. A hydrogen atom in a galaxy moving with a speed of 6.55x10^6 m/s away from the Earth

emits light with a frequency of 6.16x10^14 Hz. What frequency of light from that hydrogen atom would be observed by an astronomer on Earth? 6.03x10^14 Hz

6. An astronomer is looking at the spectrum of a galaxy and finds that it has an oxygen spectral line of 525 nm, while the laboratory value is measured at 513 nm. Calculate how fast the galaxy would be moving relative to Earth. Explain whether the galaxy is moving toward or away from Earth and how you know. 7.02x10^6 m/s

7. What color is seen when red light shines on a yellow + cyan pigment?

8. The sun is a luminous or illuminated source? How about the moon?9. What is the frequency of oxygen’s spectral line if its wavelength is 513 nm? (for nm to m

use 1∗10−9) 5.85∗1014 Hz

Mirrors1. A concave mirror has a radius of 36 cm. If the object is 12 cm tall and 58 cm from the

mirror, calculate the location, orientation, size, and type (L-O-S-T) of the image. (You should have a numerical answer for the location and size.) –See you ch.17 quiz

2. A convex security mirror in a warehouse has a -0.50 m focal length. A 2.0 m tall forklift is 5.0 m from the mirror. Calculate the location, orientation, size, and type (L-O-S-T) of the image. (You should have a numerical answer for the location and size.) See you ch.17 quiz

3. In the following diagrams, use ray diagrams to locate the images.

4. A light ray is incident upon a plane mirror at an angle of 30 degrees from the normal,

what is angle of reflection?5. An object is 36.0 cm in front of a concave mirror with a 16.0 cm focal length. Determine

the image position. 28.8 cmLenses

1. A laser beam in air is incident upon ethanol at an angle of incidence of 37.0 °. What is the angle of refraction? 26.3°

2. A block of unknown material is submerged in water. Light in the water is incident on the block at an angle of incidence of 31°. The angle of refraction of the light in the block is 27°. What is the index of refraction of the material of the block? 1.5

3. What is the speed of light in chloroform (n = 1.51)? 1.99x10^8 m/s

4. A 2.25-cm-tall object is 8.5 cm to the left of a convex lens of 5.5-cm focal length. Find the image position and height. 15.6 cm & -4.1 cm respectively

5. If the angle of incidence of light traveling through air, striking water, is 30°, what is the angle of refraction?

Circuits1. Determine the equivalent (total) resistance for each of the following circuits below.

a) Pll 1.19 Ω, b) series 7 Ω, c) series 14 Ω2. A toaster oven is plugged into an outlet that provides a voltage difference of 120 V. What power

does the oven use if the current is 10A? 1200 W3. A VCR that is not playing still uses 10.0 W of power. What is the current if the VCR is plugged

into a 120 V electric outlet? 0.83 Amps4. A flashlight bulb uses 2.4 W of power when the current in the bulb is 0.8 A. What is the voltage

difference? 3V5. A refrigerator operates on average for 10.0 h a day. If the power rating of the refrigerator is 700

W, how much electrical energy does the refrigerator use in 1 day? (make sure to convert to kW) 7kWh

6. A TV with a power rating of 200 W uses 0.8 kWh in one day. For how many hours was the TV on during this day? 4 hr

7. A current of 0.5 A flows in a 60 W light bulb when the voltage difference between the ends of the filament is 120 V. What is the resistance of the filament? 240 Ω

8. The current flowing in an appliance connected to a 120 V source is 2 A. How many kilowatt-hours of electrical energy does the appliance use in 4 h? (2 equations used & convert watts to kW) .96 kWh

9. When resistance increases what happens to the current?10. When resistance increases what happens to the voltage required? 11. Calculate the equivalent resistances of the circuits below if R1 = 2, R2 = 4, R3 = 2.

12. In the following circuit, what is the current through the 2 Ω resistor?

5 Amps13. Using the circuits below, determine how many amperes of current

will flow when four 1 Ω resistors are in this series circuit. 1.5 Amperes

14. In the circuit shown below, the meter registers 1.5 amperes. The voltage across the 10.0Ω resistor is about ___. 15.0 V

15. What is the current through the battery? 1A

16. A 9-V battery is connected to a light bulb with a resistor of 3 Ω. What is the current in the

circuit? 3 A17. An electric appliance draws 1.5 amperes of current when it is connected to a 24-volt

source. What is the resistance of this appliance? 16 Ω18. How much power is dissipated by the resistor in the circuit below?

19. Collapse the following circuit into only one equivalent resistor, then find the current through the final circuit:

20.

Additional problems:1. What is the weight (force of gravity) of a 3000 N car?2. What is the weight of a 302 kg pig?3. What is the amount of mass in a 30.0 kg child?4. What is the amount of mass in a 750 N teacher?5. What is the weight of a 1 kg apple? What is its mass?6. Would mass or weight change on the moon?7. Which is a vector: mass or weight? Why?8. Convert 5 km/h to m/s. 1.39 m/s9. You solved a problem and ended with units of kg∗m2/s2, what were you solving for and

what other unit could be used?10. You are solving a problem with units that are set up this way: [kg][m /s2][m], what are

you solving for?