Problem Q4.1DQ: Can a body be in equilibrium when only one force acts on it? Explain. Problem Q4.2DQ: A ball thrown straight up has zero velocity at its highest point. Is the ball in equilibrium at this... Problem Q4.3DQ: A helium balloon hovers in midair, neither ascending descending. Is it in equilibrium? What forces... Problem Q4.4DQ: When you fly in an airplane at night in smooth air, you have no sensation of motion, even though the... Problem Q4.5DQ: If the two ends of a rope in equilibrium are pulled with forces of equal magnitude and opposite... Problem Q4.6DQ: You tie a brick lo the end of a rope and whirl the brick around you in a horizontal circle. Describe... Problem Q4.7DQ: When a car stops suddenly, the passengers tend to move forward relative to their seats. Why? When a... Problem Q4.8DQ: Some people say that the force of inertia (or force of momentum) throws the passengers forward when... Problem Q4.9DQ: A passenger in a moving bus with no windows notices that a ball that has been at rest in the aisle... Problem Q4.10DQ: Suppose you chose the fundamental physical quantities to be force, length, and time instead of mass,... Problem Q4.11DQ: Why is the earth only approximately an inertial reference frame? Problem Q4.12DQ: Does Newtons second law hold true for an observer in Ivan as it speeds up, slows down, or rounds a... Problem Q4.13DQ: Some students refer to the quantity ma as the force of acceleration. Is it correct to refer to this... Problem Q4.14DQ: The acceleration of a falling body is measured in an elevator that is traveling upward at a constant... Problem Q4.15DQ: You can play catch with a softball in a bus moving with constant speed on a straight road, just as... Problem Q4.16DQ: Students sometimes say that the force of gravity on an object is 9.8 m/s2. What is wrong with this... Problem Q4.17DQ: Why can it hurt your foot more to kick a big rock than a small pebble? Must the big rock hurt more?... Problem Q4.18DQ: Its not the fall that hurts you; its the sudden stop at the bottom. Translate this saying into the... Problem Q4.19DQ: A person can dive into water from a height of 10 m without injury, but a person who jumps off the... Problem Q4.20DQ: Why are cars designed to crumple in front and back for safety? Why not for side collisions and... Problem Q4.21DQ: When a string barely strong enough lifts a heavy weight, it can lift the weight by a steady pull;... Problem Q4.22DQ: A large crate is suspended from the end of a vertical rope. Is the tension in the rope greater when... Problem Q4.23DQ: Which feels a greater pull due to the earths gravity; a 10-kg stone or a 20-kg stone? If you drop... Problem Q4.24DQ: Why is it incorrect to say that 1.0 kg equals 2.2 lb? Problem Q4.25DQ: A horse is hitched to a wagon. Since the wagon pulls back on the horse just as hard as the horse... Problem Q4.26DQ: True or false? You exert a push P on an object and it pushes back on you with a force F. If the... Problem Q4.27DQ: A large truck and a small compact car have a head-on collision. During the collision, the truck... Problem Q4.28DQ: When a car comes to a stop on a level highway, what force causes it to slow down? When the car... Problem Q4.29DQ: A small compact car is pushing a large van that has broken down, and they travel along the road with... Problem Q4.30DQ: Consider a tug-of-war between two people who pull in opposite directions on the ends of a rope. By... Problem Q4.31DQ: Boxes A and B are in contact on a horizontal, frictionless surface. You push on box A with a... Problem Q4.32DQ: A manual for student pilots contains this passage: When an airplane flies at a steady altitude,... Problem Q4.33DQ: If your hands are wet and no towel is handy, you can remove some of the excess water by shaking... Problem Q4.34DQ: If you squat down (such as when you examine the books on a bottom shelf) and then suddenly get up,... Problem Q4.35DQ: When a car is hit from behind, the occupants may experience whiplash. Use Newtons laws of motion to... Problem Q4.36DQ: In a head-on auto collision, passengers who are not wearing seat belts may be thrown through the... Problem Q4.37DQ: In a head-on collision between a compact 1000-kg car and a large 2500-kg car, which one experiences... Problem Q4.38DQ: Suppose you are in a rocket with no windows, traveling in deep space far from other objects. Without... Problem 4.1E: Two dogs pull horizontally on ropes attached to a post; the angle between the ropes is 60.0. If... Problem 4.2E: To extricate an SUV stuck in the mud, workmen use three horizontal ropes, producing the force... Problem 4.3E: BIO Jaw Injury. Due to a jaw injury, a patient must wear a strap (Fig. E4.3) that produces a net... Problem 4.4E: A man is dragging a trunk up the loading ramp of a movers truck. The ramp has a slope angle of 20.0,... Problem 4.5E: Forces F1 and F2act at a point. The magnitude of F1 is 9.00 N, and its direction is 60.0 above the... Problem 4.6E: An electron (mass = 9.11 1031 kg) leaves one end of a TV picture tube with zero initial speed and... Problem 4.7E: A 68.5-kg skater moving initially at 2.40 m/s on rough horizontal ice comes to rest uniformly in... Problem 4.8E: You walk into an elevator, step onto a scale, and push the up button. You recall that your normal... Problem 4.9E: A box rests on a frozen pond, which serves as a frictionless horizontal surface. If a fisherman... Problem 4.10E: A dockworker applies a constant horizontal force of 80.0 N to a block of ice on a smooth horizontal... Problem 4.11E: A hockey puck with mass 0.160 kg is at rest at the origin (x = 0) on the horizontal, frictionless... Problem 4.12E: A crate with mass 32.5 kg initially at rest on a warehouse floor is acted on by a net horizontal... Problem 4.13E: A 4.50-kg experimental cart undergoes an acceleration in a straight line (the x-axis). The graph in... Problem 4.14E: A 2.75-kg cat moves in a straight line (the x-axis). Figure E4.14 shows a graph of the x-component... Problem 4.15E: A small 8.00-kg rocket burns fuel that exerts a time varying upward force on the rocket (assume... Problem 4.16E: An astronauts pack weighs 17.5 N when she is on the earth but only 3.24 N when she is at the surface... Problem 4.17E: Superman throws a 2400-N boulder at an adversary. What horizontal force must Superman apply to the... Problem 4.18E: BIO (a) An ordinary flea has a mass of 210 g. How many newtons does it weigh? (b) The mass of a... Problem 4.19E: At the surface of Jupiters moon Io, the acceleration due to gravity is g = 1.81 m/s2. A watermelon... Problem 4.20E: A small car of mass 380 kg is pushing a large truck of mass 900 kg due east on a level road. The car... Problem 4.21E: BIO World-class sprinters can accelerate out of the starting blocks with an acceleration that is... Problem 4.22E: The upward normal force exerted by the floor is 620 N on an elevator passenger who weighs 650 N.... Problem 4.23E: Boxes A and B are in contact on a horizontal, frictionless surface (Fig. E4.23). Box A has mass 20.0... Problem 4.24E: A student of mass 45 kg jumps off a high diving board. What is the acceleration of the earth toward... Problem 4.25E: Section 4.6 Free-Body Diagrams 4.25Crates A and B sit at rest side by side on a frictionless... Problem 4.26E: You pull horizontally on block B in Fig. F4.26, causing both blocks to move together as a unit. For... Problem 4.27E: A ball is hanging from a long siring that is tied to the ceiling of a train car traveling eastward... Problem 4.28E: CP A .22-caliber rifle bullet traveling at 350 m/s strikes a large tree and penetrates it to a depth... Problem 4.29E: A chair of mass 12.0 kg is sitting on the horizontal floor: the floor is not frictionless. You push... Problem 4.30P: A large box containing your new computer sits on the bed of your pickup truck. You are stopped at a... Problem 4.31P: CP A 5.60-kg bucket of water is accelerated upward by a cord of negligible mass whose breaking... Problem 4.32P: CP You have just landed on Planet X. You release a 100-g ball from rest from a height of 10.0 m and... Problem 4.33P: Two adults and a child want to push a wheeled cart in the direction marked x in Fig. P4.33. The two... Problem 4.34P: CP An oil tankers engines have broken down, and the wind is blowing the tanker straight toward a... Problem 4.35P: CP BIO A Standing Vertical Jump. Basketball player Darrell Griffith is on record as attaining a... Problem 4.36P: CP An advertisement claims that a particular automobile can stop on a dime. What net force would be... Problem 4.37P: BIO Human Biomechanics. The fastest pitched baseball was measured at 46 m/s. A typical baseball has... Problem 4.38P: BIO Human Biomechanics. The fastest served tennis ball, served by Big Bill Tilden in 1931, was... Problem 4.39P: Two crates, one with mass 4.00 kg and the other with mass 6.00 kg, sit on the frictionless surface... Problem 4.40P: CP Two blocks connected by a light horizontal rope sit at rest on a horizontal, frictionless... Problem 4.41P: CALC To study damage to aircraft that collide with large birds, you design a test gun that will... Problem 4.42P: CP A 6.50-kg instrument is hanging by a vertical wire inside a spaceship that is blasting off from... Problem 4.43P: BIO Insect Dynamics. The froghopper (Philaenus spumarius), the champion leaper of the insect world,... Problem 4.44P: A loaded elevator with very worn cables has a total mass of 2200 kg, and the cables can withstand a... Problem 4.45P: CP After an annual checkup, you leave your physicians office, where you weighed 683 N. You then get... Problem 4.46P: CP A nail in a pine board stops a 4.9-N hammer head from an initial downward velocity of 3.2 m/s in... Problem 4.47P: CP Jumping to the Ground. A 75.0-kg man steps off a platform 3.10 m above the ground. He keeps his... Problem 4.48P: The two blocks in Fig. P4.48 are connected by a heavy uniform rope with a mass of 4.00 kg. An upward... Problem 4.49P: CP Boxes A and B are connected to each end of a light vertical rope (Fig. P4.49). A constant upward... Problem 4.50P: CP Extraterrestrial Physics. You have landed on an unknown planet, Newtonia, and want to know what... Problem 4.51P: CP CALC A mysterious rocket-propelled object of mass 45.0 kg is initially at rest in the middle of... Problem 4.52P: CALC The position of a training helicopter (weight 2.75 105N) in a test is given by r = (0.020... Problem 4.53P: DATA The table gives automobile performance data for a few types of cars: Make and Model (Year) Mass... Problem 4.54P: DATA An 8.00-kg box sits on a level floor. You give the box a sharp push and find that it travels... Problem 4.55P: DATA You are a Starfleet captain going boldly where no man has gone before. You land on a distant... Problem 4.56CP Problem 4.57PP: BIO FORCES ON A DANCER'S BODY. Dancers experience large forces associated with the jumps they make.... Problem 4.58PP: BIO FORCES ON A DANCERS BODY. Dancers experience large forces associated with the jumps they make.... Problem 4.59PP: BIO FORCES ON A DANCER'S BODY. Dancers experience large forces associated with the jumps they make.... Problem 4.60PP: The forces on a dancer can be measured directly when a dancer performs a jump on a force plate that... format_list_bulleted