Concept explainers
In February 1955, a paratrooper fell 370 m from an airplane without being able to open his chute but happened to land in snow, suffering only minor injuries. Assume that his speed at impact was 56 m/s (terminal speed), that his mass (including gear) was 85 kg, and that the magnitude of the force on him from the snow was at the survivable limit of 1.2 × 105 N. What are (a) the minimum depth of snow that would have stopped him safely and (b) the magnitude of the impulse on him from the snow?
Want to see the full answer?
Check out a sample textbook solutionChapter 9 Solutions
Fundamentals of Physics, Volume 1, Chapter 1-20
Additional Science Textbook Solutions
Organic Chemistry
Chemistry: The Central Science (14th Edition)
Genetic Analysis: An Integrated Approach (3rd Edition)
College Physics: A Strategic Approach (3rd Edition)
Introductory Chemistry (6th Edition)
Human Anatomy & Physiology (Marieb, Human Anatomy & Physiology) Standalone Book
- A project of certain space organization had to fire a rocket for some reason. If the desired position of rocket while flying is at an altitude of 15 km where the temperature is – 50°C and speed of the rocket has to correspond with Mach number 2, find the speed of the rocket. Take K = 1.4 and R = 287 J/kg °K.arrow_forwardA dog of mass Md is standing on a raft so that he is a distance Xdgi=L from the shore.arrow_forwardA tennis ball (typical mass 57.5 g) flying through the air may be affected by air resistance. The drag force applied to the ball can be approximated as: F drag C₁pAv² Where: Fdrag Drag force (N) Cd = Coefficient of drag, which for a tennis ball is around 0.55 p = The density of air, which at ground level at 25°C is around 1.2 A = The presented area of the tennis ball in the direction of travel, around 3500 mm² v = The velocity (by convention in the positive direction) in m/s (a) Draw a free-body diagram of the tennis ball during flight, including air resistance. Also include a separate vector showing the direction of travel (v) at an arbitrary angle (theta) from horizontal. (b) Write Newton's second law for the x and y directions, and from this state the first-order differential equations (in each coordinate) that govern the motion of the tennis ball The tennis ball is at a vertical height of 1.4 m above the ground when it is struck with a racquet. The initial velocity as it leaves the…arrow_forward
- A crate with a mass of m=330 kg rest on the horizontal deck of the ship. The coefficient of static friction between the crate and the deck is us=0.71. The coefficient of kinetic friction is uk =0.49. Randomized variables M= 330 kg Us= 0.71 Uk = 0.49 (A) write an expression for the minimum force, Fm, that must be applied to get the block moving from rest. (B) is the magnitude of the force FM in newtons? (C) write an expression for the force FV that must be applied to keep the block moving at a constant velocity. (D) what is the magnitude of the force FV in newtons?arrow_forwardThe resistance of air to the motion of bodies in free fall depends on many factors, such as the size of the body and its shape, the density and temperature of the air, and the velocity of the body falling through the air. A useful assumption, only approximately true, is that the resisting force takes the form FR = -kủ, where k is a constant whose value in any particular case is determined by factors other than velocity. Consider free fall of an object released from rest. (a) Show that Newton's second law gives d²y = mg dy k- dt та — тg — ku which is equivalent to m dt2 (b) What are the dimensions of k, in terms of mass (M), length (L), and time (T)? (c) Show that the body ceases to accelerate when it reaches a velocity vr = mg/k called the terminal velocity. (d) Prove, by substitution into the equation of part (a), that the velocity varies with time as v = vr (1 – e-kt/m) (e) Make sketches of v(t) and y(t). Describe any significant features of your sketches.arrow_forwardA car with two passengers and fuel weighs 1000 kg. It has wings with an area of 16 m^2 that are designed such that air moving over them must travel 1.05 times as far as air moving under them. How fast must this plane be moving so that wings generate enough lift to offset the plane's weight? The wings are thick. Please give answer in m/sarrow_forward
- A cube of tin with sides of length 2.8 m is transported to the surface of Mars. What is the weight of this cube on Mars? Express this quantity in units of lbf. The specific gravity of tin is 7.28. Gravitational acceleration on Mars is 0.38 Garrow_forwardAn object of mass 200 kg is released from rest from a boat into the water and allowed to sink. While gravity is pulling the object down, a buoyancy force of 50 times the weight of the object is pushing the object up (weight = mg). If we assume that water resistance exerts a force on the object that is proportional to the velocity of the object, with proportionality constant 20 N-sec/m, find the equation of motion of the object. After how many seconds will the velocity of the object be 70 m/sec? Assume that the acceleration due to gravity is 9.81 m/sec². First write Newton's law m = F(t,v) in terms of the given data. dv dt dv marrow_forwardIt is autumn. You look outside a window and see a maple leaf falling face down, in a straight vertical line. You estimate the speed of the leaf to be 25.77 cm/s. You then pick up the leaf and do measurements. It has a mass of 2.76 g and a cross sectional area of 76 square cm. You measure the density of air to be 1.298 kg m-³. What is the drag coefficient between the leaf and the air? (numerical value only) Number (Hint: For an object to fall with constant speed, it must be at 'terminal velocity'.)arrow_forward
- Like friction, drag force opposes the motion of a particle in a fluid; however, drag force depends on the particle's velocity. Find the expression for the particle's velocity v(x) as a function of position at any point x in a fluid whose drag force is expressed as Fdrag = kmv where k is a constant, m is the mass of the particle and v is its velocity. Assume that the particle is constrained to move in the x-axis only with an initial velocity v0. Solution: The net force along the x-axis is: ΣF = -F = m then: -mv = m Since acceleration is the first time derivative of velocity a = dv/dt, -mv = m We can eliminate time dt by expressing, the velocity on the left side of the equation as v = dx/dt. Manipulating the variables and simplifying, we arrive at the following expression / = -k "Isolating" the infinitesimal velocity dx and integrating with respect to dx, we arrive at the following: = v0 - which shows that velocity decreases in a linear manner.arrow_forwardPlease answer the question and its subquestions entirely! This is one question with two subquestions. According to the official Bartleby guidelines, I am alowed to have up to two subquestion! 1) A 50 N crate is pulled up a 5.0 m inclined plane by a worker at constant velocity. If the plane is incline at an angle of 37 o to the horizontal and there exists a frictional force of 10 N between the crate and the surface, what is the force applied by the worker? 0 N 20 N 30 N 40 N a) A girl and a boy pull in opposite directions on strings attached to each end of a spring balance. Each child exerts a force of 20 N. What will the reading on the spring balance be? 0 N 10 N 20 N 40 N b) A horizontal force of 25 N is exerted on a box with a mass of 10 kg. The box accelerates at 2.0 m/s 2. What is the magnitude of the frictional force acting between the box and the floor? 0.0 N 2.5 N 5.0 N…arrow_forwardA ball with a mass of 3.7 grams and a diameter of 4.2 cm is hung vertically from the end of a string. A strong wind, travelling at a speed of 8.9 m/s blows past, causing the ball to hang at a nonzero angle with the vertical. Determine the angle that the ball will make with the vertical when it is in static equilibrium. Assume a drag coefficient of 0.45 for a spherical object and that the density of the air is 1.21 kg/m³.arrow_forward
- Principles of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningPhysics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage Learning