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3 years ago

A weightlifter lifts a 1250-N barbell 2 m in 3 s.How much power was used to lift the barbell?

Physics

1 answer:

Vlad [161]3 years ago

5 0

The power is 833.3 W

Explanation:

First of all, we need to calculate the work done in lifting the barbell, which is equal to the change in gravitational potential energy of the barbell:

$W=(mg)h$

where

mg = 1250 N is the weight of the barbell

h = 2 m is the change in height

Substituting,

$W=(1250)(2)=2500 J$

Now we can calculate the power, which is equal to the work done per unit time:

$P=\frac{W}{t}$

where

W = 2500 J is the work done

t = 3 s is the time taken

Substituting,

$P=\frac{2500}{3}=833.3 W$

Learn more about power:

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a skier starts at rest at the top of a hill with 350 J of gravitational potential energy. Assuming energy is conserved, what is

spayn [35]

Answer:

350Joules

Explanation:

According to law of Conservation of energy, the amount of energy at the used up at the start is equal to that at the end.

The initial energy used up is gravitational potential energy

Final energy at the lowest point is kinetic energy.

If the energy is conserved then it means energy is not used up during the process hence;

Initial Potential energy = Final kinetic energy

If the gravitational potential energy is 350Joules then her final kinetic energy at the lowest point will also be 350Joules

3 0

3 years ago

How much work was done by a hot air balloon to lift up a 100 Newton to a height of 300 meters?

Monica [59]

So, the work was done by that hot air-balloon is <u>30,000 J or 30 kJ</u>.

<h3>Introduction</h3>

Hi ! In this question, I will help you. <u>Work is the amount of force exerted to cause an object to move a certain distance from its starting point</u>. In physics, the amount of work will be proportional to the increase in force and increase in displacement. Amount of work can be calculated by this equation :

$\boxed{\sf{\bold{W = F \times s}}}$

With the following condition :

W = work (J)
F = force (N)
s = shift or displacement (m)

Now, the s (displacement) can be written as ∆h (altitude change) because the object move to vertical line. The formula can also be changed to:

$\boxed{\sf{\bold{W = F \times \Delta h}}}$

With the following condition :

W = work (J)
F = force (N)
$\sf{\Delta h}$ = change of altitude (m)

If an object has mass, then the object will also be affected by gravity. Always remember that F = m × g. So that :

$\sf{W = F \times \Delta h}$

$\boxed{\sf{\bold{W = m \times g \times \Delta h}}}$

With the following condition :

W = work (J)
m = mass of the object (kg)
g = acceleration of the gravity (m/s²)
$\sf{\Delta h}$ = change of altitude (m)

<h3>Problem Solving</h3>

We know that :

F = force = 100 N
$\sf{\Delta h}$ = change of altitude 300 m

What was asked :

W = work = ... J

Step by step :

$\sf{W = F \times \Delta h}$

$\sf{W = 100 \times 300}$

$\boxed{\sf{W = 30,000 \: J = 30 \: kJ}}$

<h3>Conclusion</h3>

So, the work was done by that hot air-balloon is 30,000 J or 30 kJ.

Work that he had done to lift object brainly.com/question/26341717
Converting work to potential energy brainly.com/question/26487284

5 0

2 years ago

At which location could you place the south pole of a bar magnet so that it would be pulled toward the magnet shown?

stepan [7]

Answer:

The north pole.

Explanation:

3 0

3 years ago

6. Why does sound travel faster through a steel bar than through a swimming pool filled with water?

Lady_Fox [76]

I understand that sound travels faster in water then in air. Water is a liquid, and air is gas.

Water still has the ability to roll the molecules over each other (so water can flow), it has some flexibility.

But I do not understand how a solid that is inflexible can make sound waves travel faster then in a flexible liquid.

In fact, sound waves travel over 17 times faster through steel than through air.

Sound waves travel over four times faster in water than it would in air.

3 0

3 years ago

Why does it matter if a material is amorphous or crystalline? How does the arrangement of atoms affect the properties of materia

Rashid [163]

Answer:

<em>It matters because crystalline and amorphous materials have different properties. The arrange affects the melting point (defined in crystals and a larger range in amorphous) and shape (geometrical in crystals, no geometrical in amorphous). </em>

Explanation:

The particles that compose a solid material are held in place by strong tractive forces between them when we analyze solids we consider the position of the atoms (molecules or ions) rather than their motion (which is important in liquids and gases). This positioning can be arranged in two general ways:

Crystalline solids have internal structures that in turn lead to distinctive flat surfaces or face, these faces intersect at angles that are characteristic of the substance, crystals tend to have sharp, well defined and high melting points because of the same distance from the same number and type of neighbors. They generally have geometric shapes, some examples are diamonds, metals, salts.
Amorphous solids produce irregular or curved surfaces when broken and they have poorly defined patterns when exposed to x rays because of their irregular array. In contrast with crystal solids, amorphous solids soften over a wide temperature range due to the different amounts of thermal energy needed to overcome different interactions. Some examples of these solids are gels, plastics, and some polymers.

I hope you find this information useful and interesting! Good luck!

8 0

3 years ago