PHYSICS
A 245-kg boulder is dropped into a mine shaft that is $3.0 \times 10^{3} \mathrm{m}$ deep. During the boulder's fall, the system consisting of the earth and the boulder loses a certain amount of gravitational potential energy. It would take an equal amount of energy to "free" the boulder from the shaft by raising it back to the top, so this can be considered the system's binding energy. (a) Determine the binding energy (in joules) of the earth-boulder system. (b) How much mass does the earth-boulder system lose when the boulder falls to the bottom of the shaft?
ALGEBRA
A boulder falls down a mountain into water 64 feet below. The distance d that the boulder falls in t seconds is given by the equation $$ d = 16t^2 $$ . How long does it take the boulder to hit the water?
PHYSICS
In a canyon between two mountains, a spherical boulder with a radius of 1.4 m is just set in motion by a force of 1600 N. The force is applied at an angle of $53.5^{\circ}$ measured with respect to the vertical radius of the boulder. What is the magnitude of the torque on the boulder?
ALGEBRA
Apply the law of the lever. One end of a pry bar is under a 350 kg boulder. The fulcrum of the bar is 15 cm from the boulder and 175 cm from the other end of the bar. What mass at that end of the bar will balance the boulder?
EARTH SCIENCE
On a field trip 40 km east of the Finger Lakes, a student observed a boulder of gneiss on the sedimentary bedrock. Which inference is supported best by his observation? (1) The local sedimentary bedrock was weathered to form a boulder of gneiss. (2) The gneiss boulder was transported from its original area of formation. (3) The gneiss boulder was formed from sediments that were compacted and cemented together. (4) The local sedimentary bedrock melted and solidified to form a boulder of gneiss.
PHYSICS
A boy sleds down a hill and onto a frictionless ice-covered lake at 10.0 m/s. In the middle of the lake is a 1000-kg boulder. When the sled crashes into the boulder, he is propelled over the boulder and continues sliding over the ice. If the boy's mass is 40.0 kg and the sled's mass is 2.50 kg, what is the speed of the sled and the boulder after the collision?
EARTH SCIENCE
Suppose you find a boulder in a dry streambed. You want to know which way the water will flow after a storm. To the left of the boulder is a mound of sediment. To the right of the boulder is exposed bedrock. What can you infer about the direction of flow?
PHYSICS
Sisyphus was a character in Greek mythology who was doomed in Hades to push a boulder to the top of a steep mountain. When he reached the top, the boulder would slide back down the mountain and he would have to start all over again. Assume that Sisyphus slides the boulder up the mountain without being able to roll it, even though in most versions of the myth, he rolled it. a. If the coefficient of kinetic friction between the boulder and the mountainside is 0.40, the mass of the boulder is 20.0 kg, and the slope of the mountain is a constant $30.0^{\circ}$, what is the force that Sisyphus must exert on the boulder to move it up the mountain at a constant velocity? b. If Sisyphus pushes the boulder at a velocity of 0.25 m/s and it takes him 8.0 h to reach the top of the mountain, what is the mythical mountain’s vertical height?
PREALGEBRA
The Escobar family is planning a 7-day vacation. They would like to go to Boulder, Colorado, in December. Based on last December, Boulder had 23 days when it did not snow. If the Escobars would like it to snow on at least 3 days of their vacation, should they go to Boulder?
PHYSICS
Superman throws a 2400-N boulder at an adversary. What horizontal force must Superman apply to the boulder to give it a horizontal acceleration of $12.0 \mathrm { m } / \mathrm { s } ^ { 2 }$?
PHYSICS
A solid, uniform, spherical boulder starts from rest and rolls down a 50.0-m-high hill. The top half of the hill is rough enough to cause the boulder to roll without slipping, but the lower half is covered with ice and there is no friction. What is the translational speed of the boulder when it reaches the bottom of the hill?
PHYSICS
A large boulder is ejected vertically upward from a volcano with an initial speed of 40.0 m/s. Ignore air resistance. (a) At what time after being ejected is the boulder moving at 20.0 m/s upward? (b) At what time is it moving at 20.0 m/s downward? (c) When is the displacement of the boulder from its initial position zero? (d) When is the velocity of the boulder zero? (e) What are the magnitude and direction of the acceleration while the boulder is (i) moving upward? (ii) Moving downward? (iii) At the highest point? (f) Sketch $a_{y}-t$, $v_{y}-t$, and y-t graphs for the motion.
PHYSICS
Sledding down a hill, you are traveling at 10 m/s when you reach the bottom. You (inertia 70 kg) then move across horizontal snow toward a 200-kg boulder but jump off the sled (inertia 5.0 kg) the instant before it hits the boulder. The boulder is sitting on very slick ice and moves freely when the sled hits it. The sled bounces back, moving at 6.0 m/s. (a) At what speed does the boulder move after the sled hits it? (b) If you stayed on the sled, what would your momentum be just before you hit the boulder? (c) Suppose you and the sled hit the boulder and continue forward after the collision at 2.0 m/s. Would the boulder’s after-collision speed be higher or lower than the speed you calculated in part a?
EARTH SCIENCE
A geologist receives a call from friend asking for help identifying the type of rock that a large boulder is made of. Which questions could the geologist ask to help narrow down which type of rock it is? a. How big is the boulder? b. Is the rock hot or cold? c. What color or colors is it? d. What shape are the crystals or grains? e. How far from the river is the boulder? f. Are there crystals or grains large enough to see? g. Do you see anything that looks like layers in the boulder?
COLLEGE ALGEBRA
A boulder rolled down a mountain, traveling 6 feet in the first second. Each successive second, its distance increased by 8 feet. How far did the boulder travel after 10 seconds?
CHEMISTRY
Write electron configurations for each of the following. $\mathrm { Cu } , \mathrm { Cu } ^ { + } , \mathrm { Cu } ^ { 2+ }$
US HISTORY
How did Boulder Dam change places both nearby and far away?
CHEMISTRY
Determine how many atoms are in 10 g of pure copper (Cu). 1. Analyze the Problem Known: mass = ________ Unknown: molar mass, number of atoms 2. Solve for the Unknown Use the periodic table to find the atomic mass of copper and convert it to g/mol. __________. Complete the conversion equations. mass Cu $\times$ conversion factor = moles Cu _____ $\times$ _____ g Cu = _____ moles Cu moles Cu $\times$ conversion factor = atoms Cu _____ mol Cu $\times$ __________ atom Cu 3. Evaluate the Answer Restate the answer with correct significant digits.
CHEMISTRY
For each of the following groups, place the atoms and ions in order of decreasing size. $\mathrm { Cu }, \mathrm { Cu } ^ { + }, \mathrm { Cu } ^ { 2 + }$
ENGINEERING
A 5000-lb truck is being used to lift a 1000-lb boulder B that is on a 200-lb pallet A. Knowing the acceleration of the truck is 1 $\mathrm{ft} / \mathrm{s}^{2}$, determine (a) the horizontal force between the tires and the ground, (b) the force between the boulder and the pallet.
CHEMISTRY
In the reaction $\mathrm{Cu}+2 \mathrm{Ag}^{+} \rightarrow \mathrm{Cu}^{2+}+2 \mathrm{Ag}$, the oxidizing agent is: (1) Cu, (2) $\mathrm{Cu}^{2+}$, (3) $\mathbf{A g}^{+}$, (4) Ag
CHEMISTRY
How many moles of Cu are in 1.48 × 10$^{25}$ Cu atoms?
PHYSICS
How far above Earth’s surface must a 10,000-kg boulder be moved to increase the mass of the Earth-boulder system by 2.50 mg? Assume the same ratio of energy change to mass change as: $8.98 \times 10 ^ { 16 } \mathrm { J } / \mathrm { kg }$.
CHEMISTRY
The cell $\operatorname{Pt}(s)\left|\mathrm{Cu}^{+}(1 \mathrm{M}), \mathrm{Cu}^{2+}(1 \mathrm{M}) \| \mathrm{Cu}^{+}(1 \mathrm{M})\right| \mathrm{Cu}(s)$ has $E^{\circ}=0.364$ V. The cell $\mathrm{Cu}(s)\left|\mathrm{Cu}^{2+}(1 \mathrm{M}) \| \mathrm{Cu}^{+}(1 \mathrm{M})\right| \mathrm{Cu}(s)$ has $E^{\circ}=0.182$ V. Write the cell reaction for each cell and explain the differences in $E^{\circ}$. Calculate $G^{\circ}$ for each cell reaction to help explain these differences.
ENGINEERING
What is the composition, in weight percent, of an alloy that consists of 94.1 at% Ag and 5.9 at% Cu? The atomic weights for Ag and Cu are 107.87 g/mol and 63.55 g/mol, respectively. (A) 9.6 wt% Ag and 90.4 wt% Cu (B) 3.6 wt% Ag and 96.4 wt% Cu (C) 90.4 wt% Ag and 9.6 wt% Cu (D) 96.4 wt% Ag and 3.6 wt% Cu