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3 years ago

In which situation is no work being done?

Physics

1 answer:

soldi70 [24.7K]3 years ago

4 0

Answer:

Explanation:

A: as long as the height does not change, there is no work being done going from 1 place to the next.

B: Here's where the work is being done for A. You lift the box from ground level to the height where it settles.

C: If there is friction involved (and it sounds like there is) then there is work being done against the friction.

D: same explanation as C.

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What is electron affinity?

Andrews [41]

Answer:

The electron affinity of an atom or molecule is defined as the amount of energy released when an electron is attached to a neutral atom or molecule in the gaseous state to form a negative ion.

4 0

3 years ago

A weightlifter curls a 30 kg bar, raising it each time a distance of 0.50 m .How many times must he repeat this exercise to burn

ludmilkaskok [199]

Answer:

$N = 2141 times$

Explanation:

Each time the work done to raise a given mass is

$W = mgh$

here we know that

$m = 30 kg$

$h = 0.50 m$

now we have

$W = (30 kg)(9.81 m/s^2)(0.50)$

$W = 147.15 J$

since it is just 25% of actual energy consumed as we know its efficiency is 25%

so we have total energy consumed in this way

$E_{total} = \frac{147.15}{0.25}$

$E_{total} = 588.6 J$

now if it took N number of times so burn the fat of a pizza then

$N(588.6) = 1260 \times 10^3$

$N = 2141 times$

4 0

3 years ago

Which of the following can easily be studied objectively? history meteorology sociology theology

Vilka [71]

<h2>Answer: meteorology </h2>

Explanation:

From the given options , meteorology is the only one that can be studied objectively, since it is an interdisciplinary science that relies on basic sciences such as physics and mathematics and applied sciences to the study of the atmosphere, the weather, the phenomena produced and the physical laws that govern it. In addition, meteorology uses objective techniques to study and predict the various phenomena that occur in the atmosphere.

Unlike history, sociology and theology, in which there is a possibility of the existence of some data are subjective and not true or only based on opinions <u>without scientific evidence</u>.

8 0

3 years ago

A sample of gold has a mass of 38.6 grams and a volume of 2 cm3. What is the density of gold?

raketka [301]

Density is equal to mass divided by volume; that said, you would divide 38.6 by 2 to get your answer

7 0

4 years ago

Some Physics questions! Please help!

lesantik [10]

1) 260 km/h

Let's use the following convention:

positive x-direction = east

positive y-direction = north

Here we have to find the north component of the velocity's airplane, which means we have to find its y-component.

We can use the formula:

$v_y = v sin \theta$

where

v = 750 km/h is the magnitude of the plane's velocity

$\theta=20.0^{\circ}$ is the angle between the direction of the plane and the positive x-axis

Substituting,

$v_y = (750)(sin 20)=256.5 km/h \sim 260 km/h$

2) $24^{\circ}$ north of east

In order to find the direction of flight, we have to consider that the vector representing the displacement of the plane is the hypothenuse of a right triangle, of which the displacements along the east and north direction are the sides.

Therefore, we have

$v_x = 220 km$ is the displacement towards east

$v_y = 100 km$ is the displacement towards north

Therefore, the angle that gives the direction is given by

$tan \theta = \frac{v_y}{v_x}$

And substituting,

$\theta =tan^{-1}( \frac{100}{200})=24^{\circ}$

and this angle is measured north of east.

7 0

4 years ago