**Problem 9:**A hoist is used to lift a 780 kg car upward with an acceleration of 0.110 m/s².a) What is the net force acting on the car?b) What force was used to lift the car?**Answers:**a) 86 Nb) \(7.73 \times 10^3\) N**Diagram Explanation:**The image includes a diagram showing a car being lifted upward. There is an arrow pointing upwards alongside the car to indicate the direction of acceleration and the acceleration value \(a = 0.11 \, \text{m/s}^2\) is shown next to the arrow. The car is placed on a platform, visually representing the lifting mechanism of the hoist.

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Description: **Problem 9:**A hoist is used to lift a 780 kg car upward with an acceleration of 0.110 m/s².a) What is the net force acting on the car?b) What force was used to lift the car?**Answers:**a) 86 Nb) \(7.73 \times 10^3\) N**Diagram Explanation:**The im

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A hoist is used to lift a 780 kg car upward with an acceleration of 0.110 m/s². a) What is the net force acting on the car? b) What force was used to lift the car?

Principles of Physics: A Calculus-Based Text

5th Edition

ISBN:9781133104261

Author:Raymond A. Serway, John W. Jewett

Publisher:Raymond A. Serway, John W. Jewett

Chapter6: Energy Of A System

Section: Chapter Questions

Problem 67P

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Chris, a recent physics major, wanted to design and carry out an experiment to show that an objects mass determines its inertia. He used an ultrasound device to measure acceleration of a low-friction cart attached to a hanging block to provide the same force on the cart during each run (Fig. P6.76A). Chris varied the mass of the cart by varying the number of lead rods placed in it. Chris used Newtons second law Fx=FT=Max to predict his results. He reasoned that because FT is the same for each run, the carts acceleration should be inversely proportional to its mass: ax=FTM=constantM(1) Chriss goal was to show that his data fit Equation (1). He decided to analyze his results by plotting ax as a function of 1/M; Equation (1) predicted that he should get a straight line, passing through the origin with a slope equal to the tension (red line in Fig. P6.76B): Chris ran several trials for each run, averaged his results and estimated the error. He then plotted his data (green line in Fig. P6.76B). Chris was excited to see that he correctly predicted that the data fell along a straight line: ax=(0.27N)1M(0.048m/s2) According to the straight-line fit to the data, the slope of the line is 0.27 N, which was close to the weight of the hanging mass and therefore close to the tension in the string. Chris, though, was disappointed to see that the line had a negative intercept. Mathematically, as M, 1M0. Chris was confused because he believed that as the mass increased, the carts acceleration should approach zero. He was quite sure that he did not discover some new property of inertia or mass. After convincing himself that he was not being careless in the laboratory and that his data were correct, he started to search for an explanation for the discrepancy between his prediction and his data. Help Chris find an explanation. FIGURE P6.76 A. Chriss experimental apparatus. B. Chriss prediction (red line) and experimental results (green line).
In a laboratory model of cars skidding to a stop, data are measured for four trials using two blocks. The blocks have identical masses but different coefficients of kinetic friction with a table: k = 0.2 and 0.8. Each block is launched with speed vi = 1 m/s and slides across the level table as the block comes to rest. This process represents the first two trials. For the next two trials, the procedure is repeated but the blocks are launched with speed vi = 2 m/s. Rank the four trials (a) through (d) according to the stopping distance from largest to smallest. If the stopping distance is the same in two cases, give them equal rank. (a) vi = 1 m/s, = 0.2 (b) vi = 1 m/s, k = 0.8 (c) vi = 2 m/s, = 0.2 (d) vi =2 m/s, k = 0.8
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Elisha Graves Otis invented the elevator brake in the mid-1800s, making it possible to build tall skyscrapers with fast elevators. Todays skyscrapers are a large fraction of a mile tall; for example. Taipei 101 in Taiwan has 101 stories and is 515 m (0.32 miles) tall. The top speed of the elevator in the Taipei 101 tower is roughly three times greater than the ascent rate of a commercial jet airplane. The position and time data in the table are based on such an elevator. a. Working in SI units, make a position-versus-time graph for the elevator. (You may wish to use a spreadsheet program.) b. Describe the motion of the elevator in words. c. Find the highest speed of the elevator. When is the elevator going at this speed? d. What sort of considerations would the engineers need to make to ensure the comfort of the passengers?
A cosmic ray muon with mass m = 1.88 1028 kg impacting the Earths atmosphere slows down in proportion to the amount of matter it passes through. One such particle, initially traveling at 2.50 108 m/s in a straight line, decreases in speed to 1.50 108 m/s over a distance of 1.20 km. a. What is the magnitude of the force experienced by the muon? b. How does this force compare to the weight of the muon?
A block of ice (m = 15.0 kg) with an attached rope is at rest on a frictionless surface. You pull the block with a horizontal force of 95.0 N for 1.54 s. a. Determine the magnitude of each force acting on the block of ice while you are pulling. b. With what speed is the ice moving after you are finished pulling? Repeat Problem 71, but this time you pull on the block at an angle of 20.0.
You have been hired as an expert witness in the case of a factory owner suing a demolition company. The particular case involves a smokestack at a factory being demolished. In order to save money, the factory owner wanted to move the smokestack to a nearby factory that was being built. The demolition company guaranteed to deliver the undamaged smokestack to the new factory by toppling the smokestack freely onto a huge cushioned platform lying on the ground. The then-horizontal smokestack would have been loaded onto a long truck rig for transport to the new factory. However, as the smokestack toppled, it broke apart at a point along its length. The factory owner is blaming the demolition company for the destruction of his smokestack. The demolition company is claiming that there was a defect in the smokestack and that is the reason for its destruction. What advice do you give the attorney who is handling the case on the side of the factory owner?
An airbag in an automobile inflates when a collision occurs, which protects the passenger from serious injury (see the photo on page 254). Why does the airbag soften the blow? Discuss the physics involved in this dramatic photograph.
Casting molten metal is important in many industrial processes. Centrifugal casting is used for manufacturing pipes, bearings, and many other structures. A variety of sophisticated techniques have been invented, but the basic idea is as illustrated in Figure P4.35. A cylindrical enclosure is rotated rapidly and steadily about a horizontal axis. Molten metal is poured into the rotating cylinder and then cooled, forming the finished product. Turning the cylinder at a high rotation rate forces the solidifying metal strongly to the outside. Any bubbles are displaced toward the axis, so unwanted voids will not be present in the casting. Sometimes it is desirable to form a composite casting, such as for a bearing. Here a strong steel outer surface is poured and then inside it a lining of special low-friction metal. In some applications, a very strong metal is given a coating of corrosion-resistant metal. Centrifugal casting results in strong bonding between the layers. Suppose a copper sleeve of inner radius 2.10 cm and outer radius 2.20 cm is to be cast. To eliminate bubbles and give high structural integrity, the centripetal acceleration of each bit of metal should be at least 100g. What rate of rotation is required? State the answer in revolutions per minute.
The culling tool on a lathe is given two displacements, one of magnitude 4 cm and one of magnitude 3 cm, in each one of five situations (a) through (e) diagrammed in Figure OQ3.4. Rank these situations according to the magnitude of the total displacement of the tool, putting the situation with the greatest resultant magnitude first. If the total displacement is the same size in two situations, give those letters equal ranks.
In a laboratory model of cars skidding to a stop, data are measured for four trials using two blocks. The blocks have identical masses but different coefficients of kinetic friction with a table: k = 0.2 and 0.8. Each block is launched with speed vi = 1 m/s and slides across the level table as the block comes to rest. This process represents the first two trials. For the next two trials, the procedure is repeated but the blocks are launched with speed vi = 2 m/s. Rank the four trials (a) through (d) according to the stopping distance from largest to smallest. If the stopping distance is the same in two cases, give them equal rank. (a) vi = 1 m/s, k = 0.2 (b) vi = 1 m/s, k = 0.8 (c) vi = 2 m/s, k = 0.2 (d) vi = 2 m/s, k = 0.8
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