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3 years ago

In which activity is no work done?

Physics

2 answers:

Doss [256]3 years ago

5 0

Answer: The correct option is B.

Explanation:

Work is done when the force is applied to move an object to certain distance.

In the case of lifting a book, the work is done as the force is applied to lift the book. There will be displacement.

In the case of holding a brick, no work is done as the force is applied in this case but there is no displacement.

In the case of climbing stairs, work is done in climbing the stairs as the force is acting here. There will be displacement when the man will climb.

In the case of pushing a shopping cart, the work is done as the force is applied to a shopping cart. There will be displacement in forward direction.

Therefore, the correct answer is B.

sleet_krkn [62]3 years ago

3 0

The answer is B because you are not using force or energy as if you were if you were to lift or push something.

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The molecules of a substance become more closely packed and move more quickly.

andrey2020 [161]

When the substance are moved close together and they move more quickly they get compressed.

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3 years ago

Which has the lowest heat capacity? (values of heat capacities and calculations are unnecessary).

Brrunno [24]

The correct answer is Metals.

Generally, the specific heat of metals is low. Very high specific heat exists in water.A physical feature of matter known as heat capacity or thermal capacity is the quantity of heat that must be applied to an object in order to cause a unit change in temperature. Heat capacity is measured in joules per kelvin (J/K), the SI unit. A broad property is heat capacity. Use the following equation to determine heat capacity: heat capacity = E / T, where E is the quantity of delivered heat energy and T is the change in temperature. The formula would be as follows, for instance, if it takes 2,000 Joules of energy to raise a block's temperature by 5 degrees Celsius: 2,000 Joules per °C is the heat capacity.

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5 0

1 year ago

What is the electric potential, i.e. the voltage, 0.30 m from a point charge of 6.4 x 10-C?

Gwar [14]

Answer:

V = 192 kV

Explanation:

Given that,

Charge, $q=6.4\times 10^{-6}\ C$

Distance, r = 0.3 m

We need to find the electric potential at a distance of 0.3 m from a point charge. The formula for electric potential is given by :

$V=\dfrac{kq}{r}\\\\V=\dfrac{9\times 10^9\times 6.4\times 10^{-6}}{0.3}\\\\V=192000\ V\\\\V=192\ kV$

So, the required electric potential is 192 kV.

3 0

3 years ago

A person is trying to lift a crate that has a mass of 30 kg. The normal force of the floor is currently supplying 150N of force.

alexdok [17]

Here when an object is placed on the level floor then in that case there are two forces on the object

1). Weight of object downwards (mg)

2). Normal force due to floor which will counterbalance the weight (N)

so when no force is applied on the box at that time normal force is counter balanced by weight.

Now here it is given that A person tried to lift the box upwards

So now there are two forces on the box

1). Applied force of person

2). Normal force due to ground

So now these two forces will counter balance the weight of the crate

So we can write an equation for force balance like

$F_g = F_n + F_a$

given that

$F_g = mg$

here

m = 30 kg and

g = acceleration due to gravity = 10 m/s^2

$F_n = 150 N$

now from above equation

$30*10 = 150 + F_a$

$F_a = 300 - 150 = 150 N$

So force applied by the person must be 150 N

7 0

3 years ago

If we have a one-electron atom, and the electron can occupy any of 5 different energy levels, and transitions are possible betwe

xeze [42]

Answer:

Explanation:

Lets say that a,b,c,d,e are the five allowed energy states in order of decreasing energy. Then the number of possible different spectral lines comes from the electron dropping from a high state to a lower state. So, they will do so in following ways:

a - b

a - c

a - d

a- e

b - c

b - d

b- e

c - d

c- e

d- e

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7 0

3 years ago