Concept explainers
A fisherman sets out upstream on a river. His small boat, powered by an outboard motor, travels at a constant speed v in still water. The water (Urn’s at a lower constant speed vw. The fisherman has traveled upstream for 2.00 km when his ice chest falls out of the boat. He notices that the chest is missing only after he has gone upstream for another 15.0 min. At that point, he turns around and heads back downstream, all the time traveling at the same speed relative to the water. He catches up with the floating ice chest just as he returns to his starting point. How last is the river flowing? Solve this problem in two ways. (a) First, use the Earth as a reference frame. With respect to the Earth, the boat travels upstream at speed v − vw, and downstream at v + vw. (b) A second much simpler and more elegant solution is obtained by using the water as the reference frame. This approach has important applications in many more complicated problems; examples are calculating the motion of rockets and satellites and analyzing the scattering of subatomic particles from massive targets.
Want to see the full answer?
Check out a sample textbook solutionChapter 4 Solutions
Bundle: Physics For Scientists And Engineers With Modern Physics, 10th + Webassign Printed Access Card For Serway/jewett's Physics For Scientists And Engineers, 10th, Multi-term
- SITUATION 9. A small projectile is fired vertically downward into a fluid medium with an initial velocity of 60m/s. Due to the drag resistance of the fluid the projectile experiences a deceleration of a = -0.4v³m/s², where v is in m/s. Determine the projectile's velocity and position 4 s after it is fired.arrow_forwardA stone is thrown at a cliff with a height of h. If the stone is thrown with an initial speed of 42 m/s at an angle θ=60° and hits the cliff at A 5.5 seconds later, determine the speed of the stone when it hits A. Use g = 10 m/s/s.arrow_forwardA diver jumps off a cliff of h at an angle of 0 =38° (see figure below). He reaches a maximum height of hmaz x = 42m from the base of the cliff. Determine the speed of the diver just before he hits the water, = 3m above the top of the cliff before falling to the water below. He hits the water VA =?.Express your answer in units of m/s. Take g 9.80m/s2. Round your answer to zero decimal places. Jrmax Answer:arrow_forward
- One side of the roof of a house slopes up at 37 deg. A roofer kicks a round, flat rock that has been thrown into the roof by a neighborhood child. The rock slides straight up the incline with an initial speed of 15 m/s. The coef. of friction between the rock and the roof is 0.40. The rock slides 10.0 m up the roof to its peak. It crosses the ridge and goes into free fall, following a parabolic trajectory above the far side of the roof, with negligible air resistance. Determine the maximum height the rock reaches above the point where it was kicked.arrow_forwardA skier is at the top of a hill with height h. Starting from rest, the skier goes down to a flat area. On this flat area, there is a section of the slope with length D where the snow has melted (there is friction here). After passing the melted section, the skier goes up a smaller hill of height h2. At the top of this hill there is a drop off and the skier launches off of it with a horizontal speed. At what horizontal distance from the base of the jump does the skier land?arrow_forwardA boat leave the dock at t=0.00 s and, starting from rest maintains a constant acceleration of (o.464 m/s^2)I relative to the water. Due to currents, however, the water itself is moving with a velocity of (0.416m/s)i + (1.33 m/s)j. How fast is the boat moving, in m/s at t= 4.78 s? How far in meters is the boat from the dock at t= 4.78s?arrow_forward
- In the Marvel comic series X-Men, Colossus would sometimes throw Wolverine toward an enemy in what was called a fastball special. Suppose Colossus throws Wolverine at an angle of e = 28.1° with respect to the ground (see figure below). Wolverine is d = 2.20 m above the ground when he is released, and he leaves Colossus's hands with a speed of v. = 22.6 m/s. (a) Using conservation of energy and the components of the initial velocity, find the maximum height attained by Wolverine during the flight. (b) Using conservation of energy, what is Wolverine's speed the instant before he hits the ground? | m/sarrow_forwardA ball of mass 1.2 kg and a diameter of 36.1 cm is attached to a string of length 1.6 m. It moves in a circular path at constant speed, 5.2 m above the ground. The string makes a constant angle of 43 ° with respect to vertical. L m (a) What is the speed of the ball? (b) What is the tension in the string?arrow_forwardA skier with a mass of 63.0 kg starts from rest and skis down an icy slope that has a length of 53.0 m at an angle of 32 degrees with respect to the horizontal. At the bottom of the slope, the path levels out and becomes horizontal, the snow becomes less icy, and the skier begins to slow down, coming to rest in a distance of 122m along the horizontal path. What is the speed of the skier at the bottom of the slope? What is the coefficient of kinetic friction between the skier and the horizontal surface?arrow_forward
- In the Marvel comic series X-Men, Colossus would sometimes throw Wolverine toward an enemy in what was called a fastball special. Suppose Colossus throws Wolverine at an angle of 8 = 33.2° with respect to the ground (see figure below). Wolverine is d = 2.17 m above the ground when he is released, and he leaves Colossus's hands with a speed of v. = 17.1 m/s. (a) Using conservation of energy and the components of the initial velocity, find the maximum height attained by Wolverine during the flight. (b) Using conservation of energy, what is Wolverine's speed the instant before he hits the ground? m/sarrow_forwardAn airplane flies horizontally at a height of h = 7840 m and with a speed of 720 km/h. A package is released from the plane which then hits the ground and explodes. Find the approximate time it takes for the package to reach the ground.Select one: a. 40sb. 20sc. 30sd. 10sarrow_forwardHello, there are several variables I have had to find for this problem but I am stuck on figuring out the last two. Please help! Thank you. A rock is thrown off a cliff at an angle of 60∘ with respect to the horizontal. The cliff is 128 m high. The initial speed of the rock is 32 m/s. Known:v0= 32 m/s v0x= 16 m/s v0y= 27.6 m/s Δy= 39.12 m t(ground)= 8.76 s Δx(total)= 138.72 m Unknown: How far has it moved horizontally when it is at maximum altitude? Δx= ? What are the horizontal and vertical positions of the rock relative to the edge of the cliff at t = 4.4 s. Assume that the origin (0,0) for this part is loacted at the edge of the cliff. Enter the positions with their correct signs. Position: (x= ? , y= ?)marrow_forward
- Physics for Scientists and Engineers with Modern ...PhysicsISBN:9781337553292Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPhysics for Scientists and EngineersPhysicsISBN:9781337553278Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPrinciples of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage Learning
- University Physics Volume 1PhysicsISBN:9781938168277Author:William Moebs, Samuel J. Ling, Jeff SannyPublisher:OpenStax - Rice UniversityClassical Dynamics of Particles and SystemsPhysicsISBN:9780534408961Author:Stephen T. Thornton, Jerry B. MarionPublisher:Cengage LearningGlencoe Physics: Principles and Problems, Student...PhysicsISBN:9780078807213Author:Paul W. ZitzewitzPublisher:Glencoe/McGraw-Hill