Chemistry, 04.12.2020 18:00 ohgeezy

How can you increase the gravitational potential energy (GPE) of an empty shoe box on the bottom shelf of a bookcase? A. all of the options listed here will increase the GPE

B. add items to the box and raise it to a higher shelf

C. add items to the box to increase its mass

D. raise the box to a higher shelf

We can calculate the about of potential energy in an object using the formula PE = mgh where m is the mass of the object, g is the acceleration due to gravity (which on Earth is a constant 9.8) and h is the height the object is from ground. If I have a 2kg bar of gold and raise that to a shelf mounted 3 meters from the ground what is that objects GPE? Remember to insert the numbers into the formula like this PE = (2)B. (9.8) (3) , you may use your calculator to complete this multiplication problem.

A. 14.8 J

B. 88.2 J

C. 58.8 J

D. 176.4 J

Which is an example of only potential energy

A. a skateboard rolling down a hill.

B. a puppy sleeping on the ground under a tree.

C. an elevator moving up to the 3rd floor.

D. an apple step on top of the teacher’s desk.

If Kinetic energy has the shorted name of energy of motion, what is the shortened name for Potential Energy?

A. Stored energy

B. Joules

C. Newtons

D. Awkward energy

Potential energy can be converted into kinetic energy, a good example of this is when a pole-vaulter bends the pole during a leap. When the pole is bent the most, does it store elastic or gravitational potential energy?

A. Only gravitational potential energy because that is more powerful than elastic potential energy.

B. The pole stores gravitational potential energy because it is bent from its natural shape when off the ground.

C. The pole stores elastic potential energy when the pole is bent because its shape is change from its natural shape and it will want to go back to its original form, just like a spring or stretched elastic material.

D. It has neither elastic or gravitational potential energy.

Is the potential energy of the roller coaster elastic or gravitational?

A. neither

B. gravitational

C. elastic

D. both

In the EXPLORE section of your lesson 4.08 on Potential energy there were several animations to watch that provided a graphic illustrating how the PE and KE in a system changed as skateboarder rides a pipeline or a pendulum moves, why did the bar for the total energy remain constant?

A. Energy is converted from kinetic to potential and potential to kinetic, but the total amount of energy is conserved.

B. Because these models do not take into account the impact of friction and air resistance and are helping to solidify the concept of energy conservation and that the total mechanical energy remains constant in that model.

C. This is because no energy is being created or destroyed in this system.

D. all answers given are correct

In class we learned that a car model with a mass of 5.0 kg that is placed on a track 3.0 m off the ground and is traveling at a speed of 4 m/s. Has a measurable kinetic and potential energy. Calculate the total mechanical energy of the object using the formula ME = KE + PE when the KE is 40 joules and the PE is 147 joules. (You may use your calculator on this addition problem.)

A. 60 J

B. 147 J

C. 40 J

D. 187 J

Answers: 3

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Answers

Answer from: Quest

part 1: the half-life of the element is 22 years.

part 2: it will take 132.02 year for the sample to decay from 308.0 g to 4.8125 g.

explanation:

part 1: there are two ways to determine the half life time.

first way: the half life time can be determined directly from its definition as it is the time required for the sample to decay to its half concentration.

from the data the initial concentration was 45.0 g and decayed to its half value (22.5 g) in 22.0 years.

second way: the radio active decay is considered first order reaction so we can use the laws of first order reactions.

k = (1/t) ln (a/a-x), where k is the rate constant of the reaction,

t is the time of the reaction

a is the initial concentration of the reactant

a-x is the remaining concentration at time (t)

a = 45.0 g the initial concentration at t = 0 year.

at t = 22 year, a-x = 22.5 g

then k = (1/22 year) ln (45.0 g/ 22.5 g) = 0.0315 year-1.

the half-life time (t1/2) = ln 2/ k = 0.693/ k =0.693/ 0.0315 = 22 years.

part 2:

using the same law k = (1/t) ln (a/a-x),

using the given data; a = 308.0 g and a-x = 4.8125 g and the calculated k from the part 1 (k = 0.0315 year-1)

t = (1/k) ln (a/a-x) = (1/0.0315) ln (308.0/ 4.8125) = 132.02 years

Answer from: Quest

The answer is 323 g.

Answer from: Quest

for step 7 table c on the lab "newtons law of action" the average time it took the car to travel .25 meters was 1.92 seconds.

the average time it took the car to travel 0.50 meters was 2.61 seconds

hope this : )

Answer from: Quest

the correct answer is b. a strong acid completely dissociates to its ions when dissolved in water. $hbr$ completely dissociates to $h^+$ and $br-$ ions. a is incorrect because $h_2s$ does not fully ionize to $h^+$ and $hs^-$ ions and some remain as the compound $h_2s$ . c and d are incorrect because, $li_2o$ and $libr$ do not fall into the category of bronsted lowry acids. a bronsted lowry acid is a proton donor and since both molecules do not have a proton to donate they are not bronsted lowry acids. likewise, if we use the lewis acid definition, they cannot be acids. a lewis acid is an electron pair acceptor. both $li_2o$ and $libr$ have a complete octet so can not accept any electrons which disqualifies them as acids.