A 50 kg person is standing on a bathroom scale in an elevator moving upward. Below is my corrected answer with the elevator accelerating downward. If the person stands on the scale in an elevator moving up at a constant speed of 100 ms, what is the scale readout. The normal force, the force of the elevator on this toddlers shoes, is going to be identical to the downward force due to gravity. Once the car reaches the highest registered call it will reserve and collect all hall calls in floor sequence during downward movement. What is the velocity of each elevator relative to someone standing on the first floor. Since we are already moving at the same speed as the elevator up or down, nothing is affecting us to change our weight. The magnitude of the reaction force to the upward normal force on the passenger is. Assume that the elevators are traveling at the same speed, and that the upward direction is positive. If youre accelerating upwards in an elevator the force due to gravity and acceleration are still equal to the spring extension force so f.
Youre in an elevator that is moving at constant speed. On an upward moving escalator amit, sanjeev and vicky take 10 steps, 8 steps and 5 steps respectively to reach the top. They stay for a week in their little moving room named otis, and encounter many interesting people as they pop in for a visit between floors. However, when the elevator starts to go or stops, our body resists it. A man riding upward in a freight elevator accidentally drops a package off the elevator when it is 100 ft from the ground. Using the old method can be time consuming in competitive exams so lets discuss the classic method and the faster method. A the elevator could be moving upward at constant speed.
Now the elevator is traveling up while slowing down. A stack of books whose true weight is 165 n is placed on a scale in an elevator. Your weight is 500 newtons given in the problem the scales force is 400 newtons. Activity 4 reason an elevator is pulled upward so it moves with increasing upward speedthe force exerted by the cable on the elevator is constant and greater than the downward gravitational force exerted by earth. If the elevator accelerates upward at a 1 ms 2, then your effective mass is.
Each person weighs 600 n when the elevators are stationary. The elevator goes up because the cable is being shortened, not because an upward force is exerted on the elevator by the cable. In such an accelerating frame, you need to add extra terms to newtons law. From this information alone, can you tell whether the elevator is moving with a constant velocity of 2ms upward, is moving with a constant velocity of 2ms downward, or is at rest. When a person stands on a scale, the reading the number of pounds or newtons. So the normal force here is going to be 98 newtons.
Completely nets out the downward, the negative 98 newtons. Since your acceleration is 0 ms 2, newtons first law says the net force on you must be 0 newtons. Now that acceleration can come from either the elevator moving upward faster and faster, or by it moving downward slower and slower. Consider the free body diagram for each the case where the elevator is accelerating down left and up right. If you stand on a scale in an elevator accelerating upward, you feel heavier because the elevator s floor presses harder on your feet, and the scale will show a higher reading than when the elevator is at rest. A person of mass kg stands on a weight scale in an elevator.
An elevator moving down passes its neighbor, an elevator. B the elevator could be moving downward with decreasing speed. What is the speed of the bolt just as it hits the elevator floor. The upward normal force exerted by the floor is 620 n on an elevator passenger who weighs 650 n. Accelerate upward against direction of gravity and the scale would register a larger weight, the opposite holds true when accelerated downward with the direction of gravity. Call the scale reading for this part s in units of newtons. Elevator to nowhere give yourself goosebumps, no 34.
The person doesnt float upward here also, because again the elevator and the person move together, but the contact force between the person and the scale is reduced. If this person is standing on a bathroom scale inside the elevator, what would the scale read. The upward normal force exerted by the floor is 620 n on. Carol hedden explores the relationship between gravity, weight, and relative motion, using a moving elevator to explain the fascinating physics. Person on scale in elevator a person with mass, m, who is located at or near the surface of the earth will always have some weight wmg. The person doesnt float upward, because again the elevator and the person move together, but the contact force between the person and the scale is reduced. An elevator is being lifted upward at a constant speed by a steel cable. It discusses how to calculate the apparent weight of a person when the elevator is at rest, moving upward with constant speed, downward with. The elevator is moving upward and comes to rest vi. A the elevator could be moving upward at constant course hero.
If the magnitude of deceleration is the same as that in. While moving at a constant speed on an elevator, whether traveling up or down, your weight on a physical scale would read the same number. An elevator is moving upward at a constant speed of 2. Now, assume the elevator is moving upward at increasing speed. The delivery person weighs 160 lb and each box of books weight 50 lb. Initially, the elevator is moving upward with constant speed no acceleration so w. On the same upward moving escalator amit takes 30 steps to come down from the top.
A person who normally weighs 700 n is riding in an elevator that is moving upward but slowing down at a steady rate. If the elevator were to accelerate downward, the scale would read lighter. A the elevator could be moving upward at constant speed b. E the elevator could be moving upward with increasing speed. Consider the normal force acting on you from the elevator. Tension on a string while an elevator is moving physics. Calculate the force that a mother must exert to hold her 12. Part bnow, assume the elevator is moving upward at increasing speed. An elevator moving down passes its neighbor, an elevator moving up. So same in the elevator you are standing in the elevator so you are continuously feeling an acceleration of g but when the elevator. If the elevator accelerates downward greatly enough, then a elevator accelerates downward faster than gravity, then we see that n in that case, once the elevator accelerates downward at a g, then your feet lift off the floor and n 0, and so you feel weightless. Answer the following questions with reference to the eight forces defined as follows. On the other hand, when the elevator accelerates downward, you feel lighter. The acceleration is determined by the ratio between the change in velocity and the time it took.
Make your force diagram and net force diagram quantitative. The scale therefore has to push upward with less force on the person to support the persons weight. A 50 kg person is standing on a bathroom scale in an. In this case, the elevator and the person are initially moving upward at a constant speed and slowing down to rest at a higher floor. Suppose you are in an elevator that is moving upward. The direction that the elevator moves doesnt matter only the elevator s acceleration. A girl in an elevator is holding one end of a string, and a weight hangs from the other end. Do you weight less if going down an elevator and more if. When the elevator is moving, we will weigh our normal weight. What is the speed of the bolt just as it hits the elevator floor b according to an observer in the elevator. At some point you notice a tall wall at a distance d in front of you. A man weighing 700n is in an elevator that is accelerating upward at 4 ms.
See f is directly proportional to displacement in simple harmonic motion so fkx and fma makx xa mk time period 2. Find the forcein n exerted on his feet by the elevator floor. Tension on a string while an elevator is moving physics forums. Find the ratio of the time taken by sanjeev and vicky to reach the top. To rank items as equivalent, overlap them blocks in an elevator ranking task three blocks are stacked on top of each other inside hints an elevator as shown in eigure 1 answer the following questions with reference to the figur 1. The elevator moves down with constant speed this is exactly the same as part c. Jan 08, 2017 the upward normal force exerted by the floor is 620 n on an elevator passenger who weighs 650 n. Think of the moment an elevator begins to drop, and you can feel light for a second or two.
Part bnow, assume the elevator is moving upward at. D the tension in the supporting cable must exceed the weight of the elevator and its contents. I have added some examples along with concept so that readers can get used to such methods generally asked in exams. One force angle 30 o magnitude of the normal greatest. Rent editorial team at, our goal is to be the most efficient digital resource to help people find and live in a place they love. Part b suppose you are in an elevator that is moving upward. The required force is the normal force from the elevator floor on the mans feet give your answer in three significant figures form.
To analyze the acceleration of a moving elevator or vehicle. When the elevator is accelerating upward, which is greater, t or w. Elevator physics problem, normal force on scale, apparent weight. Chapter 4 check your understanding questions flashcards. The required force is the normal force from the elevator floor on the mans feet give your answer in three significant figures form ans. Elevators, escalators, and moving sidewalks alisa goetz on. Jim with mass of 70 kg is in an elevator that is moving up at the speed of 10 ms. Calculate the force a mother must exert to hold her 12. Not realizing that the elevator is not actually a room, and therefore, it is strange to make a home there, they move right in. To complete the diagram, add an upward force on you due to the scale. You are driving along an empty straight road at a constant speed u.
I need the answers in nnewtons can anybody help me. Person in an elevator moving upwardscale weight 36 the figures below depict situations where a person is standing on a scale in eight identical elevators. A 700 n b less than 700 n c more than 700 n d it could be more or less than 700. Sep 26, 2014 a person who normally weighs 700 n is riding in an elevator that is moving upward but slowing down at a steady rate. Solved an elevator is moving upward at a constant solutioninn. What is the upward force exerted by the floor of the elevator on a 74 kg passenger. Supplement an elevator is moving upward at a constant speed of 2. It is a pretty silly book, but my students really enjoyed it.
If the magnitude of deceleration is the same as that in part a, what is reading given by the scale. To rank items as equivalent, overlap them blocks in an elevator ranking task three blocks are stacked on top of each other inside hints an elevator as shown in eigure 1 answer the following questions with reference to the. A person has a weight of 600 n standing on a scale in an. How the normal force changes when an elevator accelerates. In which of the following cases is the magnitude of the tension in the string greatest. Oct 22, 2007 a man having a mass of 100kg stands on a bathroom scale while inside an elevator. One force angle 30 o magnitude of the normal greatest first.
Sketch separate freebody diagrams for you, the elevator by itself, and the combined system of you plus the elevator for these three situations. Would it require a larger force to a continue moving straight and decelerate to a full stop before the wall, or b turn left or right to avoid the wall. Why does a scale display a higher reading while accelerating upwards in an elevator. Why does a scale display a higher reading while accelerating. Each elevator now moves accelerates according to the specified arrow that is drawn next to it. What is the reading of the scale when the elevator is at. What happens when the elevator has an upward acceleration accelerating upward, or. The upward normal force exerted by the floor is 620 n on an. As the elevator nears the floor at which you will get off, its speed slows down. In this episode we examine the concept of a space elevator, a popular piece of developing technology designed to lift people and cargo into space at a fraction of normal launch costs. A 50 kg person is standing on a bathroom scale in an elevator.
Since the net force on you is 0 newtons, the upward forces and downward forces on you must balance exactly. The same is true when the elevator is moving at a constant velocity. Discover delightful childrens books with prime book box, a subscription that delivers new books every 1. The elevator accelerates upward momentarily at the rate of 2 ms2.
Since the elevator is at rest, your acceleration is 0 ms 2. What is toms apparent weight while the elevator is braking. Scale find s the scale reading when the elevator is moving. Isaac physics a project designed to offer support and activities in physics problem solving to teachers and students from gcse level through to university. A person stands on a scale inside an elevator at rest. If you stand on a scale in an elevator accelerating upward, you feel heavier because the elevators floor presses harder on your feet, and the scale will show a higher reading than when the elevator is at rest. In this first situation right here, this person has no acceleration. Do you weigh more when youre going up and less when youre going down.
Nov 30, 2010 now that acceleration can come from either the elevator moving upward faster and faster, or by it moving downward slower and slower. The elevator then moves with a steady speed of 5 ms. If the elevator is moving in upward direction, it will respond to car calls in floor sequence and the highest down hall call only. That tells us that we are moving in the upward direction. C the speed of the elevator changes by equal amounts in equal times. If the elevator maintains a constant upward speed of determine how high the elevator is from the ground the instant the package hits the ground. In both cases, the elevator s acceleration is 0 ms 2, so the situation inside the elevator is the same in both cases. An elevator is moving up at a constant velocity of 2. What is the upward force exerted by th floor of the elevator. The upward normal force exerted by the floor is 615 n on. Feb 25, 2012 a while the elevator moving downward and it is slowing down b while the elevator moves upward at constant speed c while the elevator is moving upward at it is slowing down d while the elevator moves downward with constant speed e while the elevator is at rest homework equations fma fmg the attempt at a solution. Elevator to nowhere give yourself goosebumps, no 34 r. That may sound complicated, but an elevator is a great way to see this.
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