Physics conservation of energy

Consider a situation where you carry a 20 N box up a flight of stairs, raising its elevation by 5 m. You drop the box. As it falls to its original level, its kinetic energy is a. 0 c. 100 J b. 4 J d. none of the above

c. 100 J

How many elements have been identified? a. 92 b. 104 c. 114 d. over 200 e. none of the above

c. 114

The pressure on A1 in psi is (네모 그림 왼쪽 A1 오른쪽 A2) a. 0.25 b. 0.4 c. 4 d. 10 e. 40

c. 4

The pressure on A2 in psi is (네모 그림 왼쪽 A1 오른쪽 A2) a. 0.25 b. 0.4 c. 4 d. 10 e. 40

c. 4

The mass of 1 cubic meter of fresh water at the top of a 100 m hydroelectric dam is 1,000 kg and it has a potential energy of 980,000 N. At the bottom of the dam, the speed of the moving water is: a. 9,800 m/s c. 44.3 m/s b. 1,960 m/s d. 98 m/s

c. 44.3 m/s √2(9.80)(100) = √1960 = 44.3 m/s

A tire pressure gauge reads 30 psi when the atmospheric pressure is 14 psi. The net force on 2 square inches of the tire is a. 28 lbs b. 32 lbs c. 60 lbs d. 88 lbs e. none of these

c. 60 lbs

Consider a situation where you carry a 20 N box up a flight of stairs, raising its elevation by 5 m. What is the impulse provided by the force? a. 150 Ns b. 50 Ns c. 75 Ns d. undetermined—not enough information given e. none of the above

c. 75 Ns

A 2 kg car moving towards the right at 4 m/s collides head on with an 8 kg car moving towards the left at 2 m/s, and they stick together. After the collision, the velocity of the combined bodies is a. 0 b. 0.8 m/s towards the right c. 0.8 m/s towards the left d. 2.4 m/s towards the right e. 2.4 m/s towards the left

c. 0.8 m/s towards the left 2x4 - 8x2 = (8+2)*V V = -8/10 = - 0.8 m/sec - sign means towards Left

Consider a situation where you carry a 20 N box up a flight of stairs, raising its elevation by 5 m. The increase of potential energy of the box is a. 0 c. 100 J b. 4 J d. none of the above

c. 100 J

Consider a situation where you carry a 20 N box up a flight of stairs, raising its elevation by 5 m. The work you do is a. 0 c. 100 J b. 4 J d. none of the above

c. 100 J

When a 4 cubic ft block of wood floats in a fluid whose weight density is 60 pounds per cubic foot, 3/4 of the block's volume is submerged. The buoyant force on the block is a. 60 lbs b. 120 lbs c. 180 lbs d. 240 lbs e. none of the above

volume submerged = 3/4 * 4 = 3 ft^3 buoyancy force = density of liquid * volume of liquid displaced = 60* 3 = 180 lbs

Which of the following is not a unit of pressure? a. atmosphere b. psi c. N/m2 d. mm of mercury e. pascal f. none of the above

f. none of the above

You carry a 20 N box 5 m horizontally across a room. The work you do is a. 0 c. 100 J b. 4 J d. none of the above

a. 0

A kid slides down an icy (frictionless) hill starting from rest. At the top his gravitational potential energy is 500 J. His kinetic energy at the top of the hill is a. 0 J c. some value between 0 and 500 J b. 500 J d. none of the above

a. 0 J

A person weighing 200 pounds stands on snowshoes. If the area of each snowshoe is 400 square inches, the pressure on the snow is a. 0.25 psi b. 0.5 psi c. 2 psi d. 4 psi e. none of the above

a. 0.25 psi Pressure= Force/Area= 200/400*2 (2 shoes)= .25psi

A helium balloon rises because of a. Archimedes' principle b. Pascal's principle c. Bernoulli's principle d. Torricelli's principle e. none of these principles

a. Archimedes' principle

The buoyant force that keeps a ship afloat is an example of a. Archimedes' principle b. Pascal's principle c. Bernoulli's principle d. Torricelli's principle e. none of these principles

a. Archimedes' principle

The particle that orbits the central core inside an atom is the a. electron b. proton c. neutron d. nucleus e. none of the above

a. electron

When an object floats in a liquid, the buoyant force is ____________ the weight of the object. a. equal to b. larger than c. smaller than d. not related to

a. equal to

A kid slides down an icy (frictionless) hill starting from rest. At the top his gravitational potential energy is 500 J. Suppose after reaching the bottom he then continues sliding up another icy slope on the other side of the valley. When he finally comes to a stop he will have reached a height a. equal to the height he started from on the other hill b. less than the height he started from on the other hill c. more than the height he started from on the other hill d. none of the above

a. equal to the height he started from on the other hill

Angular momentum a. is definitely conserved b. is definitely not conserved c. may or may not be conserved d. none of the above

a. is definitely conserved

Linear momentum a. is definitely conserved b. is definitely not conserved c. may or may not be conserved d. none of the above

a. is definitely conserved

Linear momentum a. is definitely conserved b. is definitely not conserved c. may or may not be conserved, depending on the nature of the collision d. none of the above

a. is definitely conserved

What are the SI units of momentum? a. kg m/s c. joules b. pascals d. watts

a. kg m/s

Two inflated balloons are of identical size and shape, but one is filled with hydrogen, the other helium. Which has the larger buoyant force on it? a. neither—the buoyant forces must be equal b. the helium balloon c. the hydrogen balloon d. It can't be determined.

a. neither—the buoyant forces must be equal

If a force on an object is aimed perpendicular to the direction of the object's velocity, the force does a. no work c. negative work b. positive work d. any of the above

a. no work

The quantity 1/2 mv2 is a. the kinetic energy of the crate b. the potential energy of the crate c. the linear momentum of the crate d. the work you do on the crate e. the power you supply to the crate

a. the kinetic energy of the crate

The pressure on your left palm is ____________ the pressure on your right palm. a. 1/4 b. 1/2 c. equal to d. 2 times e. 4 times

b. 1/2

A kid slides down an icy (frictionless) hill starting from rest. At the top his gravitational potential energy is 500 J. He slides part way down the hill to a point where his gravitational potential energy is 200 J. His kinetic energy at that point will be a. 200 J b. 300 J c. some unknown value between 0 and 500 J d. none of the above

b. 300 J 500-200 = 300

A kid slides down an icy (frictionless) hill starting from rest. At the top his gravitational potential energy is 500 J. He slides all the way down to the valley bottom where his gravitational potential energy becomes zero. His kinetic energy at the bottom will be a. 0 J c. some value between 0 and 500 J b. 500 J d. none of the above

b. 500 J

The pressure at the bottom of aquarium A is greater than that at the bottom of aquarium B. Why might this be? a. A is filled with fresh water, B has the same amount of salt water. b. A is filled to a greater depth than B. c. A has greater volume than B. d. The bottom of aquarium A has smaller area than that of B. e. none of the above

b. A is filled to a greater depth than B.

The brakes in a car work because of a. Archimedes' principle b. Pascal's principle c. Bernoulli's principle d. Torricelli's principle e. none of these principles

b. Pascal's principle

The hydraulic system in modern aircraft is an example of: a. Bernoulli's principle c. Archimedes' principle b. Pascal's principle d. Galileo's principle

b. Pascal's principle

In the chemical formula for water, H2O, what does the "2" mean? a. There are two oxygen (O) atoms in a molecule of water. b. There are two hydrogen (H) atoms in a molecule of water. c. The hydrogen in water is actually deuterium. d. none of the above

b. There are two hydrogen (H) atoms in a molecule of water.

Kinetic energy is conserved in a. an inelastic collision b. an elastic collision c. any collision where two objects rebound off each other d. none of the above

b. an elastic collision

A device that measures absolute air pressure is called a a. manometer b. barometer c. thermometer d. tire gauge e. none of the above

b. barometer

The molecule is the basic unit of all a. elements c. mixtures b. compounds d. solutions

b. compounds

An object moving in a circle at a steady speed has a. constant linear momentum b. constant angular momentum c. constant velocity d. constant acceleration

b. constant angular momentum

Water is flowing through a pipe whose cross sectional area at point A is larger than the cross sectional area at point B. The reading on a pressure gauge connected to the pipe at point A will be _____________ the reading on a pressure gauge connected to the pipe at point B. a. the same as c. lower than b. higher than d. unrelated to

b. higher than

If the same-sized force is made to act over a smaller area, the pressure is a. decreased b. increased c. unchanged d. dependent upon the shape of the area

b. increased

If the outside air pressure decreases, the reading on a tire gauge connected to a tire a. stays the same b. increases c. decreases d. can not be determined

b. increases

Work is done on an object when a. it moves in a circle at constant speed b. it is accelerated in a straight line c. it is carried horizontally at constant speed d. all of the above

b. it is accelerated in a straight line

The pressure exerted by a gas is the result of a. the Bernoulli effect b. molecular collisions c. Pascal's principle d. the ideal gas law e. none of the above

b. molecular collisions

DNA is a complex a. atom b. molecule c. life form d. mystery e. acronym

b. molecule

If a force on an object is aimed in the direction of the object's velocity, the force does a. no work c. negative work b. positive work d. any of the above

b. positive work

When we say work is done by a force, we mean the force does a. all the work c. negative work b. positive work d. zero work

b. positive work

The positively charged particle inside an atom is the a. electron b. proton c. neutron d. nucleus e. none of the above

b. proton

About how many 100W light bulbs would you have to light up to use energy at the rate of one horsepower? a. one or two b. seven or eight c. the question doesn't make sense—hp and W are unrelated d. dozens e. none of the above

b. seven or eight

The absolute pressure is: a. the gauge pressure plus 1 atmosphere b. the gauge pressure plus the atmospheric pressure c. the gauge pressure minus the atmospheric pressure d. the atmospheric pressure plus 14.7 psi

b. the gauge pressure plus the atmospheric pressure

Using a lever to move a rock reduces the force a person must exert. What does it do to the work the person must do? a. it reduces the work also c. the work increases b. the work stays the same d. none of the above

b. the work stays the same

Consider a situation where you carry a 20 N box up a flight of stairs, raising its elevation by 5 m. What is the magnitude of the change in the object's momentum? a. 150 kg m/s b. 50 kg m/s c. 75 kg m/s d. undetermined—not enough information given e. none of the above

c. 75 kg m/s

An atomizer works because of a. Archimedes' principle b. Pascal's principle c. Bernoulli's principle d. Torricelli's principle e. none of these principles

c. Bernoulli's principle

Which of the following is not an example of potential energy? a. The energy stored in a pile driver. b. The energy stored in a stretched spring. c. The energy of a body moving across a horizontal surface. d. The energy in the water at the top of a waterfall.

c. The energy of a body moving across a horizontal surface.

What does it mean for a physical quantity in a system to be conserved? a. It is used in the most efficient manner possible. b. It stays in its original state forever. c. The total amount of it in the system stays constant. d. none of the above.

c. The total amount of it in the system stays constant.

A plasma state of matter is a. a conducting solid b. a part of the blood c. an ionized gas d. a conducting liquid e. none of the above

c. an ionized gas

The difference between the pressures inside and outside a tire is called a. absolute pressure b. gauge pressure c. atmospheric pressure d. psi e. none of the above

c. atmospheric pressure

The upward force exerted by a fluid on an object immersed in it is called a. gravitational force b. atmospheric force c. buoyant force d. weight e. none of the above

c. buoyant force

When you suck through a straw, the force that makes the liquid go up the straw is a. a suction force b. due to surface tension c. due to the pressure of the atmosphere d. antigravity

c. due to the pressure of the atmosphere

The force on your left palm is __________ the force on your right palm. a. 1/4 b. 1/2 c. equal to d. 2 times e. 4 times

c. equal to

Internal energy a. remains constant b. decreases c. increases d. varies but in a way that cannot be predicted

c. increases

The energy of a ball rolling up an inclined plane a. is entirely kinetic b. is entirely potential c. is both kinetic and potential d. none of the above

c. is both kinetic and potential

Kinetic energy a. is definitely conserved b. is definitely not conserved c. may or may not be conserved, depending on the nature of the collision d. none of the above

c. may or may not be conserved, depending on the nature of the collision

If a force on an object is aimed opposite the direction of the object's velocity, the force does a. no work c. negative work b. positive work d. any of the above

c. negative work

When we say work is done against a force, we mean the force does a. none of the work c. negative work b. positive work d. zero work

c. negative work

The uncharged particle inside an atom is the a. electron b. proton c. neutron d. nucleus e. none of the above

c. neutron

The ratio of the density of a material to the density of water is the a. mass density b. weight density c. specific gravity d. buoyant force e. none of the above

c. specific gravity

The quantity mv is a. the kinetic energy of the crate b. the potential energy of the crate c. the linear momentum of the crate d. the work you do on the crate e. the power you supply to the crate

c. the linear momentum of the crate

After an elastic collision of two balls, the kinetic energies of the two balls are measured to be 12J and 24J. What can be said about the kinetic energy of the two balls before the collision? a. nothing—not enough information is given b. the balls had the same energies, 12J and 24J respectively c. the total kinetic energy of the two balls was 36J d. none of the above

c. the total kinetic energy of the two balls was 36J

A watt is equal to a. 746 horsepower b. one calorie c. one joule d. 1 J/s e. a unit of energy

d. 1 J/s

A person runs up a long flight of stairs in 10 seconds. If the person's weight is 600 N and the vertical height of the stairs is 20 meters, the person's power output is a. 0 b. 3 W c. 30 W d. 1,200 W e. 12,000 W

d. 1,200 W work done = force (weight) x distance ( height) = 600N x 20m = 12000J Power = 12000J/10s = 1200 watts

The cabin pressure of a passenger jet cruising at high altitude (30,000 ft) is about 1 atm. and the pressure outside is about 0.3 atm. What is the outward force on a window measuring 1 foot by 1 foot. a. 10.3 lb d. 1,481.8 lb b. 100.3 lb e. 2,116.8 lb c. 1,000.3 lb

d. 1,481.8 lb difference in pressure = 0.7 0.7 * 2116.8 = 1481.76

The gauge pressure of the water in a swimming pool at 10 ft is ____________ the gauge pressure of the water at 5 ft. a. 1/4 b. 1/2 c. equal to d. 2 times e. 4 times

d. 2 times

A mechanic working on a 100 m radar tower drops a hammer weighing 44.5 N. The work done on the hammer as it falls is: a. 4.45 N-m c. 445 N-m b. 44.5 N-m d. 4,450 N-m

d. 4,450 N-m 44.5 *100 = 4450 J

The mass of 1 cubic meter of fresh water is 1,000 kg. At the top of a 100 m hydroelectric dam the potential energy of the cubic meter of water is: a. 10,000 N c. 100,000 N b. 98,000 N d. 980,000 N

d. 980,000 N 1000x9.8x100 = 980000

The mass of 1 m3 of fresh water is 1,000 kg. At the top of a hydroelectric dam the potential energy of the water is: a. 1,000 N b. 9,800 N c. 500 N d. There is not enough information to calculate the potential energy

d. There is not enough information to calculate the potential energy

For a body oscillating at the end of a spring, the energy is a. kinetic energy b. elastic potential energy c. gravitational potential energy d. all of the above e. none of the above

d. all of the above

When people get into a small boat it settles lower in the water and a. the buoyant force increases as a result of more water being displaced b. the net force on the boat again becomes zero c. the pressure on the bottom of the boat becomes greater because it is deeper in the water d. all of the above

d. all of the above

Which of the following quantities are conserved in an isolated system? a. mass c. momentum b. energy d. all of the above

d. all of the above

The linear momentum of a truck will be greater than that of a bus if a. the truck's mass is larger than the bus's but its speed is the same b. the truck's speed is larger than the bus's but its mass is the same c. the truck's mass and speed are both larger than the bus's d. any of the above

d. any of the above

What elements do the symbols H, O, C, and N stand for? a. hydrogen, ozone, carbon, nitrogen b. hydrogen, oxygen, chlorine, nitrogen c. hydrogen, oxygen, carbon, natrium d. hydrogen, oxygen, carbon, nitrogen e. none of the above

d. hydrogen, oxygen, carbon, nitrogen

What elements do the symbols Fe, Na, Au, and Hg stand for? a. aluminum, nitrogen, silver, tungsten b. iron, sulfur, silver, ytterbium c. iron, sodium, silver, mercury d. iron, sodium, gold, mercury e. none of the above

d. iron, sodium, gold, mercury

The central core inside an atom is the a. electron b. proton c. neutron d. nucleus e. none of the above

d. nucleus

The quantity Fd is a. the kinetic energy of the crate b. the potential energy of the crate c. the linear momentum of the crate d. the work you do on the crate e. the power you supply to the crate

d. the work you do on the crate

Consider a situation where you carry a 20 N box up a flight of stairs, raising its elevation by 5 m. What is the work done by the force? a. 150 J b. 50 J c. 75 J d. undetermined—not enough information given e. none of the above

d. undetermined—not enough information given

If pressure inside a cylinder with a circular hatch is 2 atm and the radius of the entrance hatch is 12 inches, what force does the air exert on the hatch ? Recall that the area of a circle is pr2 a. 24 lb b. 288 lb c. 904.8 lb d. 1,300.6 lb e. 13,300.6 lb

e. 13,300.6 lb 2x14.7x(12^2)x3.1416 = 13,300.6

The force F2 in pounds needed to keep piston 2 in place is(네모 그림 왼쪽 A1 오른쪽 A2) a. 0.25 b. 0.4 c. 4 d. 10 e. 40

e. 40

A solid object labeled A weighs more than another solid object labeled B. Which of the following are true? a. A occupies more volume than B. b. A has a greater weight density than B. c. A has a greater specific gravity than B. d. A has greater volume but lesser weight density than B. e. none of the above

e. none of the above

About how big is an atom? a. too small to measure b. about a millionth of a meter across c. about a billionth of a meter across d. about a trillionth of a meter across e. none of the above

e. none of the above

The quantity Fd/t is a. the kinetic energy of the crate b. the potential energy of the crate c. the linear momentum of the crate d. the work you do on the crate e. the power you supply to the crate

e. the power you supply to the crate