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Tarzan \((m=85.0 \mathrm{kg})\) tries to cross a river by swinging from a vine. The vine is 10.0 \(\mathrm{m}\) long, and his speed at the bottom of the swing (as he just clears the water) will be 8.00 \(\mathrm{m} / \mathrm{s}\) . Tarzan doesn't know that the vine has a breaking strength of 1000 \(\mathrm{N}\) . Does he make it safely across the river?

Short Answer

Expert verified
The tension in the vine when Tarzan is at the bottom of the swing is 1377.85 \(\mathrm{N}\), which exceeds the breaking strength of 1000 \(\mathrm{N}\). Therefore, he does not make it safely across the river.

Step by step solution

01

Calculate the tension in the vine at the bottom of the swing

To find out if Tarzan makes it safely across the river, we first need to calculate the tension in the vine when Tarzan is at the bottom of the swing. The tension can be found using the centripetal force formula which is the sum of the gravitational force and the centrifugal force at the bottom of the swing. The formula is: \(T = mg + \frac{mv^2}{r}\) where \(T\) is the tension, \(m\) is the mass, \(g\) is the acceleration due to gravity (9.81 \(\mathrm{m/s^2}\)), \(v\) is the velocity at the bottom, and \(r\) is the length of the vine.
02

Input the given values into the tension formula

Input Tarzan's mass \(m = 85.0 \mathrm{kg}\), the gravitational acceleration \(g = 9.81 \mathrm{m/s^2}\), the length of the vine \(r = 10.0 \mathrm{m}\), and the speed at the bottom of the swing \(v = 8.00 \mathrm{m/s}\) into the tension formula: \(T = (85.0 \mathrm{kg})(9.81 \mathrm{m/s^2}) + \frac{(85.0 \mathrm{kg})(8.00 \mathrm{m/s})^2}{10.0 \mathrm{m}}\).
03

Calculate the tension at the bottom of the swing

Perform the calculations to find the tension: \(T = (85.0 \mathrm{kg})(9.81 \mathrm{m/s^2}) + \frac{(85.0 \mathrm{kg})(8.00 \mathrm{m/s})^2}{10.0 \mathrm{m}} = (85.0 \mathrm{kg})(9.81 \mathrm{m/s^2}) + (85.0 \mathrm{kg})(6.4 \mathrm{m/s^2}) = 833.85 \mathrm{N} + 544.00 \mathrm{N} = 1377.85 \mathrm{N}\).
04

Compare the tension with the vine's breaking strength

The vine's breaking strength is 1000 \(\mathrm{N}\), which is less than the calculated tension of 1377.85 \(\mathrm{N}\). Since the tension exceeds the breaking strength of the vine, Tarzan will not make it safely across the river—the vine will break.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Tension in Physics
Imagine you're holding a rope during a game of tug-of-war. That force pulling on your hands? That's tension. In physics, tension is the pulling force transmitted through a string, cable, or any similar object when forces act at its ends. It's important because it confronts other forces, such as gravity.

In Tarzan's daring swing across the river, the vine he's holding experiences tension. This is much like the tension in the rope during tug-of-war, but instead of two teams pulling on either end, we've got Tarzan's mass and the force due to his swinging motion. Tension keeps Tarzan moving in a circular path and prevents him from flying off tangentially. But tension has a limit, called breaking strength, and if exceeded - snap! - the object can no longer maintain its structural integrity. In Tarzan's case, to stay aloft, the vine's tension must remain below its breaking point.
Centripetal Acceleration
When something moves in a circle, it doesn't just go; it accelerates. Centripetal acceleration is the phenomenon that keeps an object moving in a circular path, constantly pulling it toward the center.

Imagine being on a merry-go-round. You're moving in a circle yet constantly pulled inward; that's centripetal acceleration at work. In the context of our vine-swinging hero, Tarzan, his speed gives rise to this inward 'pulling' acceleration. To calculate it, we use the formula \(a_c = \frac{v^2}{r}\), where \(a_c\) is the centripetal acceleration, \(v\) is the velocity, and \(r\) is the radius of the circular path. Using this concept, as part of our calculations in the problem, we determined how much additional force is exerted on the vine due to Tarzan's motion.
Circular Motion
Circular motion is the movement of an object along the circumference of a circle or rotation along a circular path. It can be uniform, with constant angular rate of rotation and constant speed, or non-uniform, with changing rates of rotation. When Tarzan swings from a vine, he moves in a portion of a circle which constitutes circular motion.

The span of the vine and the gravitational pull on Tarzan combine to create an experience going beyond a simple straight line. This type of movement involves both velocity (a speed in a given direction) and acceleration (rate of change of velocity). Because the vine creates a fixed radius for Tarzan's swing, and gravity keeps him tethered to Earth, his circular motion is the dramatic and dangerous game of balancing between falling and flying. Here, it was crucial in figuring out if he could safely make it across the river - spoiler, he couldn't!

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Most popular questions from this chapter

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