Concept explainers
In which of the following situations is there zero net force on the body? (i) An airplane flying due north at a steady 120 m/s and at a constant altitude; (ii) a car driving straight up a hill with a 3° slope at a constant 90 km/h; (iii) a hawk circling at a constant 20 km/h at a constant height of 15 m above an open field; (iv) a box with slick, frictionless surfaces in the back of a truck as the truck accelerates forward on a level road at 5 m/s2.
Learn your wayIncludes step-by-step video
Chapter 4 Solutions
University Physics with Modern Physics (14th Edition)
Additional Science Textbook Solutions
Life in the Universe (4th Edition)
College Physics (10th Edition)
College Physics
An Introduction to Thermal Physics
The Cosmic Perspective Fundamentals (2nd Edition)
Lecture- Tutorials for Introductory Astronomy
- One or more external forces are exerted on each object enclosed in a dashed box shown in the figures below. Identify the reaction to each of these forces. (Assume that (a), (b) and (c) occur on Earth while (d), (e) and (f) occur far from any outside gravitational influences. Select all that apply.) m Contact forces www. Field forces M (a) the spring exerts a force to the left on the wall upward on the Earth to the right on the wall downward on the Earth to the right on the hand to the left on the hand X b e +Q C Iron Narrow_forwardContact forces Ww. a Field forces +Q S M Iron N m earrow_forwardA four-person bobsled (total mass =630 kg) comes down a straightaway at the start of a bobsled run.The straightaway is 80.0 m long and is inclined at a constant angle of 10.2 with the horizontal. Assume that the combined effects of friction and air drag produce on the bobsled a constant force of 62.0 N that acts parallel to the incline and up the incline. Answer the following questions to three significant digits. (a) If the speed of the bobsled at the start of the run is 6.20 m/s, how long does the bobsled take to come down the straightaway? (b) Suppose the crew is able to reduce the effects of friction and air drag to 42.0 N. For the same initial velocity, how long does the bobsled now take to come down the straightaway?arrow_forward
- Calculate the force required to pull a stuffed toy duck (mass m = 1.75 kg) at a constant velocity of 3.8 m/s horizontally across the floor if the string is 49.0° above the horizontal. The coefficient of kinetic friction between the duck and the floor is 0.60.arrow_forwardA cooler (mass 3 kg) is initially at rest on a horizontal floor. It is then pushed in a straight line for 1.5 m by a small child who exerts a horizontal force with magnitude 37.5 N.arrow_forwardA person drags a sled across a frozen lake to town. The surface of the lake is quite smooth and slippery (so the friction from the ice can be neglected), but he has studded boots with nails driven through the soles (from the inside) so he can walk across the ice without slipping. Once the sled is moving at a reasonable speed (about the pace he can walk comfortably), in order to keep the sled moving at this speed he needs to Pull with a constant force. Not pull at all. Pull with a decreasing force. Pull with an increasing force.arrow_forward
- "A worker drags a crate across a factory floor by pulling on a rope tied to the crate. The worker exerts a force of magnitude F = 400N on the rope, which is inclined at an upward angle q = 30° to the horizontal, and the floor exerts a horizontal force of magnitude f = 200N that opposes the motion. Calculate the magnitude of the acceleration (in the unit m/s?) of the crate if its mass is 200 kg." 0.73 0.63 0.53 0.43 ооооarrow_forwardSisyphus was a character in Greek mythology and was doomed in Hades to push a boulder to the top of a steep mountain. When he reached the top, the boulder would roll back down the mountain and he would have to start all over again. The coefficient of static friction between the boulder and the mountainside is 0.200, the mass of the boulder is 136kg (300 lbs), and the slope of the mountain is a constant 30.00. What is the force in pounds that Sisyphus must exert on the boulder to move it up the mountain at a constant velocity?arrow_forwardA 600 Kg car is moving on a level road at 30 m/s. (a) How large is the retarding force(assumed constant) is required to stop it in a distance of 70 m? (b) What is the minimum coefficient of friction between the tires and the roadway if this is possible ?arrow_forward
- The parachute on a race car of weight 8 820 N opens at the end of a quarter-mile run when the car is traveling at 35 m/s. What total retarding force must be supplied by the parachute to stop the car in a distance of 1 000 m?arrow_forwardA mover pushes a 30.0 kg crate across a wooden floor at a constant speed of 0.75 m|s. If the coefficient of static friction for wood-on-wood is 0.20, what is the normal force exerted by the floor on the crate?arrow_forwardWhen a 25-kg crate is pushed across a frictionless horizontal floor with a force of 200 N, directed 20° below the horizontal, the approximate magnitude of the normal force of the floor on the crate is: O 310 N none of the given choices O 25 N O 68 N O 180 Narrow_forward
- College PhysicsPhysicsISBN:9781305952300Author:Raymond A. Serway, Chris VuillePublisher:Cengage LearningUniversity Physics (14th Edition)PhysicsISBN:9780133969290Author:Hugh D. Young, Roger A. FreedmanPublisher:PEARSONIntroduction To Quantum MechanicsPhysicsISBN:9781107189638Author:Griffiths, David J., Schroeter, Darrell F.Publisher:Cambridge University Press
- Physics for Scientists and EngineersPhysicsISBN:9781337553278Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningLecture- Tutorials for Introductory AstronomyPhysicsISBN:9780321820464Author:Edward E. Prather, Tim P. Slater, Jeff P. Adams, Gina BrissendenPublisher:Addison-WesleyCollege Physics: A Strategic Approach (4th Editio...PhysicsISBN:9780134609034Author:Randall D. Knight (Professor Emeritus), Brian Jones, Stuart FieldPublisher:PEARSON