Physics, 07.02.2022 22:50 gaby06

A person lifts a package weighing 23 Kg. If she lifts it 2.8 m off the floor, what work has she done?

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Answers

Answer from: kutsarver

So, the work done by her is 631.12 J.

Introduction

Hello ! I will help you regarding energy and its transformation. In this case, it's the use of energy from the lifter to be equivalent to potential energy, because the box undergoes a change in height and the potential energy specializes at a certain height. Work (W) due to change in potential energy ( $\sf{\Delta PE}$ ) can be realized in the equation :

$\sf{W = \Delta PE}$

$\sf{W = m \cdot g \cdot h_2 - m \cdot g \cdot h_2}$

$\boxed{\sf{\bold{W = m \cdot g \cdot (h_2 - h_1)}}}$

With the following condition :

W = work (J)m = mass of the objects (kg) $\sf{h_2}$ = final height of object (m) $\sf{h_1}$ = initial height of object (m)g = acceleration of the gravity (m/s²)Problem Solving

We know that :

m = mass of the objects = 23 kg $\sf{h_2}$ = final height of object = 2.8 m $\sf{h_1}$ = initial height of object = 0 mg = acceleration of the gravity = 10 m/s²

What was asked :

W = work = ... J

Step by Step :

$\sf{W = m \cdot g \cdot (h_2 - h_1)}$

$\sf{W = 23 \cdot 9.8 \cdot (2.8 - 0)}$

$\sf{W = 23 \cdot 9.8 \cdot 2.8}$

$\boxed{\sf{W = 631.12 \: J}}$

So, the work done by her is 631.12 J.

See More :Another example of calculating the energy required to lift an object

Answer from: Quest

i believe the answer would be:

d. violin, clarinet, french horn, and tuba

Answer from: Quest

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.

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