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Ch 02: Kinematics in One Dimension
Knight Calc - Physics for Scientists and Engineers 5th Edition
Knight Calc5th EditionPhysics for Scientists and EngineersISBN: 9780137344796Not the one you use?Change textbook
Chapter 2, Problem 20b

Ball bearings are made by letting spherical drops of molten metal fall inside a tall tower—called a shot tower—and solidify as they fall. What is the bearing's impact velocity?

Verified step by step guidance
1
Identify the key variables: The problem involves free fall motion, so we need the height of the tower (h) and the acceleration due to gravity (g = 9.8 m/s²). The initial velocity (u) is 0 m/s since the ball bearings are dropped from rest.
Use the kinematic equation for velocity in free fall: v=2gh. This equation relates the final velocity (v) to the height (h) and gravitational acceleration (g).
Substitute the known values into the equation: Replace g with 9.8 m/s² and h with the given height of the tower (you'll need the specific height value to proceed).
Simplify the expression under the square root: Perform the multiplication of 2, g, and h to find the value inside the square root.
Take the square root of the result to calculate the final velocity (v). This will give you the impact velocity of the ball bearing when it reaches the ground.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Free Fall

Free fall refers to the motion of an object under the influence of gravity alone, without any air resistance. In the context of the shot tower, the molten metal drops fall freely from a height, accelerating downwards due to gravitational force. The impact velocity can be calculated using the equations of motion for free-falling objects.
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Kinematic Equations

Kinematic equations describe the relationship between an object's displacement, initial velocity, final velocity, acceleration, and time. For an object in free fall, the relevant equation to find the final velocity just before impact is v = u + at, where 'u' is the initial velocity (zero for a drop), 'a' is the acceleration due to gravity, and 't' is the time of fall.
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Impact Velocity

Impact velocity is the speed of an object just before it collides with another object or surface. It is influenced by the height from which the object falls and the acceleration due to gravity. In this scenario, calculating the impact velocity of the molten metal involves determining how fast it is moving just before it solidifies upon hitting the ground.
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Related Practice
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Write a short description of the motion of a real object for which FIGURE EX1.20 would be a realistic position-versus-time graph.

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As a science project, you drop a watermelon off the top of the Empire State Building, 320 m above the sidewalk. It so happens that Superman flies by at the instant you release the watermelon. Superman is headed straight down with a speed of 35 m/s. How fast is the watermelon going when it passes Superman?

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A rock is tossed straight up from ground level with a speed of 20 m/s. When it returns, it falls into a hole 10 m deep. What is the rock's speed as it hits the bottom of the hole?

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Textbook Question

Ball bearings are made by letting spherical drops of molten metal fall inside a tall tower—called a shot tower—and solidify as they fall. If a bearing needs 4.0 s to solidify enough for impact, how high must the tower be?

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