Question

1. do you do more work lifting a box from the floor to the top of a table, or from the floor to a shelf above your head? why?
2. which will probably break a pane of glass, a small rock sitting on the glass, or the same rock thrown at the glass? why?
3. state the main kind of energy associated with the following sources.

a. earbuds
b. a match before it is struck
c. the led on a dvd player display
d. a battery
e. a stove burner
f. a power - plant that uses uranium for fuel

1. does the identity of an uncharged atom change when it becomes an ion? explain.
2. why is a compound considered a pure substance?
3. what is the difference between the molecules of an element and the molecules of a compound?
4. which changes in matter can produce an atom different from the original?

true or false

1. classifying matter by state is a simple and reliable way to tell mixtures and pure substances apart.
2. the most common state of matter in the universe is the solid state.
3. the more vapor particles in a given volume of air, the higher the condensation temperature, or dew point, will be.
4. mass, weight, and volume are all ways to measure matter.
5. when you exert a force, two forces are actually at work.
6. magnetism is the most important field force in geology.
7. mechanical energy is always related to a force.
8. sound energy and thermal energy result from different kinds of particle motion.
9. chemical energy can become other kinds of energy during chemical changes.
10. some energy is permanently lost when one kind of energy is converted into another.
11. mechanical work is equal to the product of a force acting on an object and the distance the object moves. if a rock weighing 15 lb falls to the foot of a 55 ft cliff, how much work has gravity done on the rock as it hits the ground?

Explanation:

Step1: Recall work - formula

The formula for work is $W = F\times d$, where $W$ is work, $F$ is force, and $d$ is distance. The force due to gravity on the rock is its weight. Here, the weight of the rock $F = 15$ lb and the distance it falls $d=55$ ft.

Step2: Calculate work

Substitute the values of $F$ and $d$ into the work - formula: $W=15\times55$.
$W = 825$ ft - lb.

Answer:

825 ft - lb