# A 26 kg bear slides, from rest, 11 m down a lodgepole pine tree, moving with a speed of 4.1 m/s...

## Question:

A 26 kg bear slides, from rest, 11 m down a lodgepole pine tree, moving with a speed of 4.1 m/s just before hitting the ground.

a. What change occurs in the gravitational potential energy of the bear-Earth system during the slide?

b. What is the kinetic energy of the bear just before hitting the ground?

c. What is the average frictional force that acts on the sliding bear?

## Work-Energy Theorem:

The theorem states that the kinetic energy gained by an object is a result of the net-work done on it.

When a body of mass m is at a height h above the ground, it possesses potential energy given by mgh where g is the gravitational acceleration value. When such a body falls, it loses potential energy and gains kinetic energy Ek given by {eq}E_k = \frac{1}{2}mv^2 {/eq}, where v is the velocity gain. However, practically, some work is done against friction and so the value of v and hence the kinetic energy Ekis less than the expected value.

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Part a

The gravitational potential energy Ep of the mass-Earth system is given by mgh where m is the mass of the object, g is the gravitational... Work-Energy Theorem: Definition and Application

from

Chapter 8 / Lesson 7
25K

Work and energy are closely related in physics. In this lesson, you'll learn what that relationship is as well as how we can apply it to various situations.