Questions and Answers of College Physics A Strategic Approach 2nd

Two coupled boxcars are rolling along at 2.5 m/s when they collide with and couple to a third, stationary boxcar. a. What is the final speed of the three coupled boxcars? b. What fraction of the
How long will it take a rock dropped from 2.0 m above the surface of Mars to reach the ground?
Mars has a small moon, Phobos, that orbits with a period of 7 h 39 min. The radius of Phobos' orbit is 9.4 x 106 m. Use only this information (and the value of G) to calculate the mass of Mars.
Europa, a satellite of Jupiter, is believed to have a liquid ocean of water (with a possibility of life) beneath its icy surface. In planning a future mission to Europa, what is the fastest that an
In Problems 70 through 73 you are given the equation (or equations) used to solve a problem. For each of these, you are toa. Write a realistic problem for which this is the correct equation. The last
In Problems 70 through 73 you are given the equation (or equations) used to solve a problem. For each of these, you are toa. Write a realistic problem for which this is the correct equation. The last
The 2.0 kg, uniform, horizontal rod in Figure P7.19 is seen from the side. What is the gravitational torque about the point shown? 25 cm FIGURE 75 cm P7.19
The 2.0-m-long, 15 kg beam in Figure P7.22 is hinged at its left end. It is "falling" (rotating clock- wise, under the influence of gravity), and the figure shows its position at three different
As divers stand on tiptoes on the edge of a diving platform, in preparation for a high dive, as shown in Figure Q8.5, they usually extend their arms in front of them. Why do they do this? FIGURE Q8.5
A spring is attached to the floor and pulled straight up by a string. The string's tension is measured. The graph in Figure Q8.10 shows the tension in the spring as a function of the spring's length
A spring exerts a 10 N force after being stretched by 1 cm from its equilibrium length. By how much will the spring force increase if the spring is stretched from 4 cm away from equilibrium to 5 cm
You must lean quite far forward as you rise from a chair (try it!). Explain why.
How much torque must the pin exert to keep the rod in Figure P8.6 from rotating? Calculate this torque about an axis that passes through the point where the pin enters the rod and is perpendicular to
Where are the centers of gravity of the two people doing the classic yoga poses shown in Figure Q8.6? (a) FIGURE Q8.6 (b)
Take a spring and cut it in half to make two springs. Is the spring constant of these smaller springs larger, smaller, or the same as the spring constant of the original spring? Explain.
Steel nails are rigid and unbending. Steel wool is soft and squishy. How would you account for this difference?
A magazine rack has a center of gravity 16 cm above the floor, as shown in Figure P8.13. Through what maximum angle, in degrees, can the rack be tilted without falling over? 16 cm 5.0 cm FIGURE
Two children carry a lightweight 1.8-m-long horizontal pole with a water bucket hanging from it. The older child supports twice as much weight as the younger child. How far is the bucket from the
A car manufacturer claims that you can drive its new vehicle across a hill with a 47° slope before the vehicle starts to tip. If the vehicle is 2.0 m wide, how high is its center of gravity?
The uniform rod in Figure Q8.15 has a weight of 14.0 N. What is the magnitude of the normal force exerted on the rod by the surface?A. 7 N B. 14 N C. 20 N D. 28 N Frictionless surface FIGURE Q8.15
A thin 2.00 kg box rests on a 6.00 kg board that hangs over the end of a table, as shown in Figure P8.15. How far can the center of the box be from the end of the table before the board begins to
A student lies on a very light, rigid board with a scale under each end. Her feet are directly over one scale, and her body is positioned as shown in Figure Q8.16. The two scales read the values
The object shown in Figure P8.16 is made of a uniform material. What is the greatest that x can be without the object tipping over? 4.0 cm 2.0 cm FIGURE P8.16 2.0 cm
For the student in Figure Q8.16, approximately how far from her feet is her center of gravity?A. 0.6 m B. 0.8 m C. 1.0 m D. 1.2 m 65 lb FIGURE Q8.16 2.0 m 100 lb
One end of a spring is attached to a wall. A 25 N pull on the other end causes the spring to stretch by 3.0 cm. What is the spring constant?
You have a heavy piece of equipment hanging from a 1.0-mm- diameter wire. Your supervisor asks that the length of the wire be doubled without changing how far the wire stretches. What diameter must
A 30.0-cm-long board is placed on a table such that its right end hangs over the edge by 8.0 cm. A second identical board is stacked on top of the first, as shown in Figure Q8.22. What is the largest
A 1.2 kg block is hung from a vertical spring, causing the spring to stretch by 2.4 cm. How much farther will the spring stretch if a 0.60 kg block is added to the 1.2 kg block?
Two 20 kg blocks are connected by a 2.0-m-long, 5.0-mm- diameter rope. Young's modulus for this rope is 1.5 X 109 N/m2. The rope is then hung over a pulley, so that the blocks, hanging from each side
A runner wearing spiked shoes pulls a 20 kg sled across frictionless ice using a horizontal spring with spring constant 1.5 X 102 N/m. The spring is stretched 20 cm from its equilibrium length. What
You need to make a spring scale to measure the mass of objects hung from it. You want each 1.0 cm length along the scale to correspond to a mass difference of 0.10 kg. What should be the value of the
A force stretches a wire by 1.0 mm. a. A second wire of the same material has the same cross section and twice the length. How far will it be stretched by the same force? b. A third wire of the
What hanging mass will stretch a 2.0-m-long, 0.50-mm- diameter steel wire by 1.0 mm?
How much force does it take to stretch a 10-m-long, 1.0-cm- diameter steel cable by 5.0 mm?
A 1.2-m-long steel rod with a diameter of 0.50 cm hangs vertically from the ceiling. An auto engine weighing 4.7 kN is hung from the rod. By how much does the rod stretch?
A mine shaft has an elevator hung from a single steel-wire cable of diameter 2.5 cm. When the cable is fully extended, the end of the cable is 500 m below the support. How much does the fully
The normal force of the ground on the foot can reach three times a runner's body weight when the foot strikes the pavement. By what amount does the 52-cm-long femur of an 80 kg runner compress at
An 80 kg construction worker sits down 2.0 m from the end of a 1450 kg steel beam to eat his lunch, as shown in Figure P8.36. The cable supporting the beam is rated at 15,000 N. Should the worker be
A woman weighing 580 N does a pushup from her knees, as shown in Figure P8.38. What are the normal forces of the floor on.(a) Each of her hands (b) Each of her knees? 54 cm 76 cm FIGURE P8.38
A man is attempting to raise a 7.5-m-long, 28 kg. flagpole that has a hinge at the base by pulling on a rope attached to the top of the pole, as shown in Figure P8.41. With what force does the man
A "rocket car" is launched along a long straight track at t = 0 s. It moves with constant acceleration a1 = 2.0 m/s2. At t = 2.0 s, a second car is launched along a parallel track, from the same
If an astronaut can jump straight up to a height of 0.50 m on earth, how high could he jump on the moon?A. 1.2 m B. 3.0 m C. 3.6 m D. 18 m
On the earth, an astronaut can safely jump to the ground from a height of 1.0 m; her velocity when reaching the ground is slow enough to not cause injury. From what height could the astronaut safely
On the earth, an astronaut throws a ball straight upward; it stays in the air for a total time of 3.0 s before reaching the ground again. If a ball were to be thrown upward with the same initial
a. Can a vector have nonzero magnitude if a component is zero? If no, why not? If yes, give an example. b. Can a vector have zero magnitude and a nonzero component? If no, why not? If yes, give an
A car goes around a corner in a circular are at constant speed. Draw a motion diagram including positions, velocity vectors, and acceleration vectors.
a. Is the object's average speed between points 1 and 2 greater than, less than, or equal to its average speed between points 0 and 1? Explain how you can tell. b. Find the average acceleration
Figure 3.11 showed the motion diagram for Anne as she rode a Ferris wheel that was turning at a constant speed. The inset to the figure showed how to find the acceleration vector at the lowest point
A position vector with magnitude 10 m points to the right and up. Its x-component is 6.0 m. What is the value of its y-component?
An athlete performing the long jump tries to achieve the maximum distance from the point of takeoff to the first point of touching the ground. After the jump, rather than land upright, she extends
A person trying to throw a ball as far as possible will run forward during the throw. Explain why this increases the distance of the throw.
A passenger on a jet airplane claims to be able to walk at a speed in excess of 500 mph. Can this be true? Explain.
If you go to a ski area, you'll likely find that the beginner's slope has the smallest angle. Use the concept of acceleration on a ramp to explain why this is so.
Draw each of the following vectors, then find its x- and y-components. à a. b. c. à = (100 m, 45° below +x-axis) (300 m/s, 20° above +x-axis) (5.0 m/s², -y-direction)
In an amusement-park ride, cars rolling along at high speed suddenly head up a long, straight ramp. They roll up the ramp. reverse direction at the highest point, then roll backward back down the
There are competitions in which pilots fly small planes low over the ground and drop weights, trying to hit a target. A pilot flying low and slow drops a weight; it takes 2.0 s to hit the ground,
Draw each of the following vectors, then find its x- and y-components. d = (2.0 km, 30° left of +y-axis) (5.0 cm/s, -x-direction) (10 m/s², 40° left of -y-axis) a. b. c. à
Each of the following vectors is given in terms of its x- and y-components. Draw the vector, label an angle that specifies the vector's direction, then find the vector's magnitude and direction. a.
A cyclist goes around a level, circular track at constant speed. Do you agree or disagree with the following statement: "Because the cyclist's speed is constant, her acceleration is zero." Explain.
Each of the following vectors is given in terms of its x- and y-components. Draw the vector, label an angle that specifies the vector's direction, then find the vector's magnitude and direction. a.
You are driving your car in a circular path on level ground at a constant speed of 20 mph. At the instant you are driving north, and turning left, are you accelerating? If so, toward what point of
While visiting England, you decide to take a jog and find yourself in the neighborhood shown on the map in Figure P3.15. What is your displacement after running 2.0 km on Strawberry Fields, 1.0 km on
An airplane has been directed to fly in a clockwise circle, as seen from above, at constant speed until another plane has landed. When the plane is going north, is it accelerating? If so, in what
When you go around a corner in your car, your car follows a path that is a segment of a circle. To turn safely, you should keep your car's acceleration below some safe upper limit. If you want to
Which combination of the vectors shown in Figure Q3.17 has the largest magnitude? A TR0 B FIGURE Q3.17 Ĉ
You begin sliding down a 15° ski slope. Ignoring friction and air resistance, how fast will you be moving after 10 s?
Two vectors appear as in Figure Q3.18. Which combination points directly to the left? TA FIGURE Q3.18 ē
A car traveling at 30 m/s runs out of gas while traveling up a 5.0° slope. How far will it coast before starting to roll back down?
In the Soapbox Derby, young participants build nonmotorized cars with very low friction wheels. Cars race by rolling down a hill. The track at Akron's Derby Downs, where the national championship is
The gas pedal in a car is sometimes referred to as "the accelerator." Which other controls on the vehicle can be used to produce acceleration? A. The brakes. B. The steering wheel. C. The gear
Two children who are bored while waiting for their flight at the airport decide to race from one end of the 20-m-long moving sidewalk to the other and back. Phillippe runs on the side- walk at 2.0
A skydiver deploys his parachute when he is 1000 m directly above his desired landing spot. He then falls through the air at a steady 5.0 m/s. There is a breeze blowing to the west at 2.0 m/s. a. At
A football is kicked at an angle of 30° with a speed of 20 m/s. To the nearest second, how long will the ball stay in the air? A. 1 s B. 2 s C. 3 sD. 4 s
A football is kicked at an angle of 30° with a speed of 20 m/s. To the nearest 5 m, how far will the ball travel? A. 15 m B. 25 m C. 35 m D. 45 m
A ball is thrown horizontally from a 20-m-high building with a speed of 5.0 m/s.a. Make a sketch of the ball's trajectory. b. Draw a graph of vy, the horizontal velocity, as a function of time.
Riders on a Ferris wheel move in a circle with a speed of 4.0 m/s. As they go around, they experience a centripetal acceleration of 2.0 m/s. What is the diameter of this particular Ferris wheel? A.
A ball with a horizontal speed of 1.25 m/s rolls off a bench 1.00 m above the floor. a. How long will it take the ball to hit the floor? b. How far from a point on the floor directly below the edge
King Arthur's knights use a catapult to launch a rock from their vantage point on top of the castle wall, 12 m above the moat. The rock is launched at a speed of 25 m/s and an angle of 30 above the
Two spheres are launched horizontally from a 1.0-m-high table. Sphere A is launched with an initial speed of 5.0 m/s. Sphere B is launched with an initial speed of 2.5 m/s. a. What are the times for
Racing greyhounds are capable of rounding corners at very high speeds. A typical greyhound track has turns that are 45-m- diameter semicircles. A greyhound can run around these turns at a constant
A CD-ROM drive in a computer spins the 12-cm-diameter disks at 10,000 rpm. a. What are the disk's period (in s) and frequency (in rev/s)? b. What would be the speed of a speck of dust on the
Entrance and exit ramps for freeways are often circular stretches of road. As you go around one at a constant speed, you will experience a constant acceleration. Suppose you drive through an entrance
A typical set of stairs is angled at 38°. You climb a set of stairs at a speed of 3.5 m/s. a. How much height will you gain in 2.0 s? b. How much horizontal distance will you cover in 2.0 s?
A pilot in a small plane encounters shifting winds. He flies 26.0 km northeast, then 45.0 km due north. From this point, he flies an additional distance in an unknown direction, only to find himself
A small plane is 100 km south of the equator. The plane is flying at 150 km/h at a heading of 30 to the west of north. In how many minutes will the plane cross the equator?
A block slides along the frictionless track shown in Figure P3.54 with an initial speed of 5.0 m/s. Assume it turns all the corners smoothly, with no loss of speed.a. What is the block's speed as it
When the moving sidewalk at the airport is broken, as it often seems to be, it takes you 50 s to walk from your gate to the bag- gage claim. When it is working and you stand on the moving side- walk
Mary needs to row her boat across a 100-m-wide river that is flowing to the east at a speed of 1.0 m/s. Mary can row the boat with a speed of 2.0 m/s relative to the water. a. If Mary rows straight
A flock of ducks is trying to migrate south for the winter, but they keep being blown off course by a wind blowing from the west at 12 m/s. A wise elder duck finally realizes that the solution is to
A 1500 kg car is traveling along a straight road at 20 m/s. Two seconds later its speed is 21 m/s. What is the magnitude of the net force acting on the car during this time?
Tennis balls experience a large drag force. A tennis ball is hit so that it goes straight up and then comes back down. The direction of the drag force is. A. Always up. B. Up and then down. C.
Very small forces can have tremendous effects on the motion of very small objects. Consider a single electron, with a mass of 9.1 x 10-31 kg, subject to a single force equal to the weight of a penny,
The Gulf Stream off the east coast of the United States can flow at a rapid 3.6 m/s to the north. A ship in this current has a cruising speed of 10 m/s. The captain would like to reach land at a
A spring-loaded gun, fired vertically, shoots a marble 6.0 m straight up in the air. What is the marble's range if it is fired horizontally from 1.5 m above the ground?
A mountain climber is hanging from a rope in the middle of a crevasse. The rope is vertical. Identify the forces on the mountain climber.
In a shot-put event, an athlete throws the shot with an initial speed of 12.0 m/s at a 40.0° angle from the horizontal. The shot leaves her hand at a height of 1.80 m above the ground. a. How far
Water at the top of Horseshoe Falls (part of Niagara Falls) is moving horizontally at 9.0 m/s as it goes off the edge and plunges 53 m to the pool below. If you ignore air resistance, at what angle
Suppose the designers of the water slide want to adjust the height h above the water so that riders land twice as far away from the bottom of the slide. What would be the necessary height above the
Whiplash injuries during an automobile accident are caused by the inertia of the head. If someone is wearing a seatbelt, her body will tend to move with the car seat. However, her head is free to
During which section of the motion is the magnitude of the acceleration experienced by a rider the greatest? A. The first. B. The second. C. The third. D. It is the same in all sections.

Showing 1300 - 1400 of 1464