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3 years ago

The question is in the picture

Physics

1 answer:

Sedbober [7]3 years ago

7 0

Answer:

e) 120m/s

Explanation:

When the ball reaches its highest point, its velocity becomes zero, meaning

$v_0-gt = 0$ .

where $v_0$ is the initial velocity.

Solving for $t$ we get

$t = \dfrac{v_0}{g}$

which is the time it takes the ball to reach the highest point.

Now, after the ball has reached its highest point, it turns around and falls downwards. After time $t_0$ since it had reached the highest point, the ball has traveled downwards and the velocity $v_f$ it has gained is

$v_f = gt_0$ ,

and we are told that this is twice the initial velocity $v_0$ ; therefore,

$v_f = 2v_0 = gt_0$

which gives

$t_0 = \dfrac{2v_0}{g}.$

Thus, the total time taken to reach velocity $2v_0$ is

$t_{tot} = t+t_0 = \dfrac{v_0}{g}+\dfrac{2v_0}{g}$

$t_{tot} = \dfrac{3v_0}{g}.$

This $t_{tot}$ , we are told, is 36 seconds; therefore,

$36= \dfrac{3v_0}{g},$

and solving for $v_0$ we get:

$v_0 = \dfrac{36g}{3}$

$v_0 = \dfrac{36s(10m/s^2)}{3}$

$\boxed{v_0 = 120m/s}$

which from the options given is choice e.

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How have the competing explanations' experiments on atoms affected the development of the atomic model?

olga2289 [7]

Answer

Competing explanations' experiments on atoms gave a perfect modal of an atom

Explanation

There is a long story of atom. Different scientist gave different theories related to atomic modal but no one individually gave a perfect modal they perfect each other work and finally we got a perfect modal of atom.

Here is a short story of atom

in 400 B.C.E, Democritus was the first philosopher who gave the concept of atom. He believes that everything is made up of tiny spheres and these spheres are known as atoms.

in 1803, Dalton said that atoms of an element are similar. For example all atoms of carbon are similar.

in 1904 J. J. Thomson proposed that atom is sphere in which positively charged matter is filled and electrons are randomly scattered in that positively charged matter.

in 1911, Rutherford gave the concept of nucleus he believed that at the center of atoms all positively charged particles are present and this center is known as nucleus. He said that negatively charge electrons revolves around the nucleus in particular orbit.

In 1913, Niels Bohr gave a new model he believes that atomic model is similar to planetary modal. He believed that the electrons in an atom revolves around the nucleus in sets of orbits in a similar manner like the planets revolves around the sun.

In 1919, Rutherford gave the concept of proton.

In 1932, James Chadwick gives the concept of neutron.

In this way different scientist gave different theories related to atoms and finally they all gave a perfect modal of atom.

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2 years ago

How is thermal energy naturally transferred between objects?

Sladkaya [172]

The second law of thermodynamics establishes restrictions on the flow of thermal energy between two bodies. This law states that the energy does not flow spontaneously from a low temperature object T1, to another object that is at a high temperature T2.

For example. Suppose you place your cell phone on the table. Your phone is at a temperature of 40 ° C and the table is at 19 ° C. Then, it is impossible for the table to spontaneously transfer its thermal energy to the telephone, and so that the table gets colder and the telephone warmer.

Finally we can say that the correct option is B: From the hotter object to the cooler object

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3 years ago

Electrons contribute___

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3 years ago

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A policeman is chasing a criminal across a rooftop at 10 m/s. He decides to jump to the next building which is 2 meters across f

valina [46]

Answer:

They will meet at a distance of 7.57 m

Given:

Initial velocity of policeman in the x- direction, $u_{x} = 10 m/s$

The distance between the buildings, $d_{x} = 2.0 m$

The building is lower by a height, h = 2.5 m

Solution:

Now,

When the policeman jumps from a height of 2.5 m, then his initial velocity, u was 0.

Thus

From the second eqn of motion, we can write:

$h = ut + \frac{1}{2}gt^{2}$

$h = \frac{1}{2}gt^{2}$

$2.5 = \frac{1}{2}\times 10\times t^{2}$

t = 0.707 s

Now,

When the policeman was chasing across:

$d_{x} = u_{x}t + \frac{1}{2}gt^{2}$

$d_{x} = 10\times 0.707 + \frac{1}{2}\times 10\times 0.5 = 9.57 m$

The distance they will meet at:

9.57 - 2.0 = 7.57 m

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3 years ago

A gas, behaving ideally, has a pressure P1 and at a volume V1. The pressure of the gas is changed to P2. Using Avogadro’s, Charl

Bond [772]

Answer:

Boyle's Law

$\therefore P_1.V_1=P_2.V_2$

Explanation:

Given that:

initially:

pressure of gas, $= P_1$

volume of gas, $= V_1$

finally:

pressure of gas, $= P_2$

volume of gas, $= V_2$

To solve for final volume $V_2$

According to Avogadro’s law the volume of an ideal gas is directly proportional to the no. of moles of the gas under a constant temperature and pressure.

According to the Charles' law, at constant pressure the volume of a given mass of an ideal gas is directly proportional to its temperature.

But here we have a change in the pressure of the Gas so we cannot apply Avogadro’s law and Charles' law.

Here nothing is said about the temperature, so we consider the Boyle's Law which states that at constant temperature the volume of a given mass of an ideal gas is inversely proportional to its pressure.

Mathematically:

$P_1\propto \frac{1}{V_1}$

$\Rightarrow P_1.V_1=k\ \rm(constant)$

$\therefore P_1.V_1=P_2.V_2$

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3 years ago