Essential University Physics (3rd Edition)
3rd Edition
ISBN: 9780134202709
Author: Richard Wolfson
Publisher: PEARSON
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Textbook Question
Chapter 4.5, Problem 4.4GI
For each of the following situations, would the cable tension in Example 4.3 be (a) greater than, (b) less than, or (c) equal to the elevator’s weight? (1) elevator starts moving upward, accelerating from rest; (2) elevator decelerates to a stop while moving upward; (3) elevator starts moving downward, accelerating from rest; (4) elevator slows to a stop while moving downward; (5) elevator is moving upward with constant speed
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Problem 5:
In the two cases shown below, a person is standing on a scale in an elevator. The elevators are identical, and the
person weighs 500 N. In both cases the elevator is moving upward, but in Case A it is accelerating upward and in
Case B it is accelerating downward.
A
B
y = 3 m/s
v = 3 m/s
a=2 m/s?
a=2 m/s?
Will the scale reading in Case A be greater than, less than, or the same as the scale reading in Case B?
Explain with a calculation or in words.
The coefficient of static friction between an 8 kg box at rest and a 35° inclined plane is 0.70. Determines whether the object starts moving or stays in a static state. Justify your answer. If the object starts moving, what happens to the coefficient of friction? Also, describes the movement of the box.
A woman weighing 600 N stands on a scale in an elevator. She presses the
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downward, the scale will read:
Less than 600 N
O 600 N
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O It is impossible to know
Chapter 4 Solutions
Essential University Physics (3rd Edition)
Ch. 4.2 - A curved barrier lies on a horizontal tabletop, as...Ch. 4.2 - A nonzero net force acts on an object. Which of...Ch. 4.4 - A popular childrens book explains the...Ch. 4.5 - For each of the following situations, would the...Ch. 4.6 - The figure shows two blocks with two forces acting...Ch. 4.6 - (1) Would the answer to (a) in Example 4.5 change...Ch. 4 - Distinguish the Aristotelian and Galilean/New...Ch. 4 - A ball bounces off a wall with the same speed it...Ch. 4 - We often use the term inertia to describe human...Ch. 4 - Does a body necessarily move in the direction of...
Ch. 4 - A truck crashes into a stalled car. A student...Ch. 4 - A barefoot astronaut kicks a ball, hard, across a...Ch. 4 - The surface gravity on Jupiters moon Io is...Ch. 4 - In paddling a canoe, you push water backward with...Ch. 4 - Is it possible for a nonzero net force to act on...Ch. 4 - As your plane accelerates down the runway, you...Ch. 4 - A driver tells passengers to buckle their...Ch. 4 - If you cut a spring in half, is the spring...Ch. 4 - As youre sitting on a chair, theres a...Ch. 4 - Section 4.2 Newtons First and Second Laws A subway...Ch. 4 - A 61-Mg railroad locomotive can exert a 0.12-MN...Ch. 4 - A small plane accelerates down the runway at 7.2...Ch. 4 - A car leaves the road traveling at 110 km/h and...Ch. 4 - By how much does the force required to stop a car...Ch. 4 - Kinesin is a motor protein responsible for moving...Ch. 4 - Starting from rest and undergoing constant...Ch. 4 - In an egg-dropping contest, a student encases an...Ch. 4 - In a front-end collision, a 1300-kg car with...Ch. 4 - Show that the units of acceleration can be written...Ch. 4 - Your spaceship crashes on one of the Suns planets....Ch. 4 - Your friend can barely lift a 35-kg concrete block...Ch. 4 - A cereal box says net weight 340 grams. Whats the...Ch. 4 - Youre a safely engineer for a bridge spanning the...Ch. 4 - The gravitational acceleration at the...Ch. 4 - A 50-kg parachutist descends at a steady 40 km/h....Ch. 4 - A 930-kg motorboat accelerates away from a dock at...Ch. 4 - An elevator accelerates downward at 2.4 m/s2. What...Ch. 4 - At 560 metric tons, the Airbus A-380 is the worlds...Ch. 4 - Youre an engineer working on Ares I, NASAs...Ch. 4 - You slop into an elevator, and it accelerates to a...Ch. 4 - What upward gravitational force does a 5600-kg...Ch. 4 - Your friends mass is 65 kg. If she jumps off a...Ch. 4 - What force is necessary to stretch a spring 48 cm,...Ch. 4 - A 35-N force is applied to a spring with spring...Ch. 4 - A spring with spring constant k = 340 N/m is used...Ch. 4 - A 1.25-kg object is moving in the x-direction at...Ch. 4 - An airplane encounters sudden turbulence, and you...Ch. 4 - A 74-kg tree surgeon rides a cherry picker lift to...Ch. 4 - A dancer executes a vertical jump during which the...Ch. 4 - Find expressions for the force needed to bring an...Ch. 4 - An elevator moves upward at 5.2 m/s. Whats its...Ch. 4 - A 2.50-kg object is moving along the x-axis at...Ch. 4 - Blocks of 1.0, 2.0, and 3.0 kg are lined up on a...Ch. 4 - A child pulls an 11-kg wagon with a horizontal...Ch. 4 - Biophysicists use an arrangement of laser beams...Ch. 4 - A force F is applied to a spring of spring...Ch. 4 - A 22(M)-kg airplane pulls two gliders, the first...Ch. 4 - A biologist is studying the growth of rats on the...Ch. 4 - An elastic towrope has spring constant 1300 N/m....Ch. 4 - A 2.0-kg mass and a 3.0-kg mass are on a...Ch. 4 - Youre an automotive engineer designing the crumple...Ch. 4 - Frogs tongues dart out to catch insects, with...Ch. 4 - Two large crates, with masses 640 kg and 490 kg,...Ch. 4 - What force do the blades of a 4300-kg helicopter...Ch. 4 - What engine thrust (force) is needed to accelerate...Ch. 4 - Your engineering firm is asked to specify the...Ch. 4 - With its fuel tanks half full, an F-35A jet...Ch. 4 - Two springs have the same unstretched length but...Ch. 4 - Although we usually write Newtons second law for...Ch. 4 - A railroad car is being pulled beneath a grain...Ch. 4 - A block 20% more massive than you hangs from a...Ch. 4 - Youre asked to calibrate a device used to measure...Ch. 4 - A spider of mass ms drapes a silk thread of...Ch. 4 - Figure 4.27 shows vertical accelerometer data from...Ch. 4 - A hockey stick is in contact with a 165-g puck for...Ch. 4 - After parachuting through the Martian atmosphere,...Ch. 4 - Your airplane is caught in a brief, violent...Ch. 4 - Youre assessing the Engineered Material Arresting...Ch. 4 - Two masses are joined by a massless string. A 30-N...Ch. 4 - A mass M hangs from a uniform rope of length L and...Ch. 4 - Jerk is the rate of change of acceleration, and...Ch. 4 - Laptop computers are equipped with accelerometers...Ch. 4 - Laptop computers are equipped with accelerometers...Ch. 4 - Laptop computers are equipped with accelerometers...Ch. 4 - Laptop computers are equipped with accelerometers...
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