Physics for Scientists and Engineers: Foundations and Connections
1st Edition
ISBN: 9781133939146
Author: Katz, Debora M.
Publisher: Cengage Learning
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Chapter 4, Problem 68PQ
Frequently, a weapon must be fired at a target that is closer than the weapon’s maximum range. To hit such a target, a weapon has two possible launch angles (Fig. P4.68A): one higher than 45° (θH) and one lower than 45° (θL). Although the displacement of the projectile is the same for the two angles, a projectile launched at θH has a longer flight time and a higher peak position than one launched at θL. Usually, some tactical situation makes one angle preferable to the other. For example, if the projectile must go over some nearby object such as a grove of trees, the higher angle may be desirable. A shorter flight time and therefore θL are preferable if the target is mobile.
In practice, many weapons are designed to operate either at angles lower than 45° or at angles higher than 45°, but not both. Tanks, for example, often must face mobile targets; to minimize the time the target has to move, tanks fire at low angles. Grenades, on the other hand, are launched at high angles because a soldier launching a grenade is often close to the target, but has no armor plating for protection. The high launch angle allows the soldier to stay out of sight by hiding behind some obstacle, and the longer flight time may make it possible for the soldier to move farther from the exploding grenade.
FIGURE P4.68
Imagine an unusual scenario in which a large gun mounted on a vehicle is required to hit an explosives factory (Fig. P4.68B). A huge explosion is expected, and there must be time for the gunner to retreat. A grove of trees provides cover. The maximum range of the gun is 17.6 km, and the maximum speed of the vehicle is 80.0 km/h. a. What is the muzzle speed v0? (Muzzle speed is the speed at which the projectile leaves the barrel of the gun.) b. The target is 5.5 km away. Find the low angle θL and the high angle θH at which the gunner may aim so as to hit the target. c. Find the time the projectile takes to hit the target for both angles. d. Assume the vehicle retreats at its maximum speed (80.0 km/h) to be as far from the ensuing explosion as possible. How far is it from the factory at the time of the explosion for each launch angle?
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Chapter 4 Solutions
Physics for Scientists and Engineers: Foundations and Connections
Ch. 4.1 - CASE STUDY How Many Dimensions? In each case,...Ch. 4.2 - Based on the particles motion diagram in Figure...Ch. 4.3 - Prob. 4.3CECh. 4.5 - Prob. 4.4CECh. 4.5 - Prob. 4.5CECh. 4.6 - A particle travels at a uniform linear speed...Ch. 4.8 - Prob. 4.7CECh. 4 - Prob. 1PQCh. 4 - In each case, determine whether the object is...Ch. 4 - CASE STUDY Imagine an indoor tennis court on a...
Ch. 4 - A basketball player dribbles the ball while...Ch. 4 - A motion diagram of a bouncing ball is shown in...Ch. 4 - Prob. 6PQCh. 4 - Prob. 7PQCh. 4 - Figure P4.8 shows the motion diagram of two balls,...Ch. 4 - Prob. 9PQCh. 4 - Prob. 10PQCh. 4 - Prob. 11PQCh. 4 - If a particles speed is always increasing, what...Ch. 4 - Prob. 13PQCh. 4 - An aircraft flies at constant altitude (with...Ch. 4 - A glider is initially moving at a constant height...Ch. 4 - If the vector components of the position of a...Ch. 4 - A If the vector components of a particles position...Ch. 4 - Prob. 18PQCh. 4 - A The spiral is an example of a mathematical form...Ch. 4 - A circus performer stands on a platform and throws...Ch. 4 - Anthony carelessly rolls his toy car off a...Ch. 4 - A physics student stands on a second-story balcony...Ch. 4 - During the battle of Bunker Hill, Colonel William...Ch. 4 - A During the battle of Bunker Hill, Colonel...Ch. 4 - A softball is hit with an initial velocity of 29.0...Ch. 4 - Figure P4.8 shows the motion diagram of two balls....Ch. 4 - A circus performer throws an apple toward a hoop...Ch. 4 - An arrow is fired with initial velocity v0 at an...Ch. 4 - A rock is thrown horizontally off a 56.0-m-high...Ch. 4 - A projectile is launched up and to the right over...Ch. 4 - Sienna tosses a ball from the window of her...Ch. 4 - Some cats can be trained to jump from one location...Ch. 4 - Dock diving is a great form of athletic...Ch. 4 - A graduate student discovers that the only...Ch. 4 - The bola is a traditional weapon used for tripping...Ch. 4 - In three different driving tests, a car moves with...Ch. 4 - A child swings a tennis ball attached to a 0.750-m...Ch. 4 - A Two particles A and B move at a constant speed...Ch. 4 - Prob. 39PQCh. 4 - Prob. 40PQCh. 4 - Prob. 41PQCh. 4 - A pendulum constructed with a bowling ball at the...Ch. 4 - Prob. 43PQCh. 4 - Prob. 44PQCh. 4 - Pete and Sue, two reckless teenage drivers, are...Ch. 4 - Prob. 46PQCh. 4 - Prob. 47PQCh. 4 - A brother and sister, Alan and Beth, have just...Ch. 4 - A man paddles a canoe in a long, straight section...Ch. 4 - Prob. 50PQCh. 4 - Prob. 51PQCh. 4 - Prob. 52PQCh. 4 - Suppose at one point along the Nile River a...Ch. 4 - Prob. 54PQCh. 4 - Prob. 55PQCh. 4 - Prob. 56PQCh. 4 - Prob. 57PQCh. 4 - Two bicyclists in a sprint race begin from rest...Ch. 4 - A particle has a nonzero acceleration and a...Ch. 4 - A golfer hits his approach shot at an angle of...Ch. 4 - You are watching a friend practice archery when he...Ch. 4 - Prob. 62PQCh. 4 - Prob. 63PQCh. 4 - David Beckham has lined up for one of his famous...Ch. 4 - Prob. 65PQCh. 4 - Prob. 66PQCh. 4 - Prob. 67PQCh. 4 - Frequently, a weapon must be fired at a target...Ch. 4 - Prob. 69PQCh. 4 - Prob. 70PQCh. 4 - Prob. 71PQCh. 4 - An observer sitting on a park bench watches a...Ch. 4 - Prob. 73PQCh. 4 - Prob. 74PQCh. 4 - Prob. 75PQCh. 4 - Prob. 76PQCh. 4 - Prob. 77PQCh. 4 - Prob. 78PQCh. 4 - A circus cat has been trained to leap off a...Ch. 4 - Prob. 80PQCh. 4 - An experimentalist in a laboratory finds that a...Ch. 4 - Prob. 82PQ
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