30 points must be a legitimate answer and correct answer or I will report

What is one characteristic of a sample of matter that indicates it is a pure substance? A) It can be separated using by a physic

snow_lady [41]

D) If the composition of a sample is fixed, the sample is a pure substance.

Explanation:

A) It can be separated by using physical means, such as filtering.

Of course using physical means as filtration or crystallization we increase the purity of a compound, however sometimes impurities may remain dissolved in the solution or they may co-precipitate with the analysed sample.

B) The components in a pure substance do not have to be in definite ratios.

If the components in a substance do not have definite rations it means the the substance is not pure, it is a mixture of something.

C) If the composition of a sample varies, the sample is a pure substance.

If the composition of a sample varies, it means that different components in the substance are changing so it is a clue that the substance is not pure.

D) If the composition of a sample is fixed, the sample is a pure substance.

If the composition of a sample is fixed, and it can be determined and proven, the substance is pure.

Learn more about:

pure substances

brainly.com/question/1339017

#learnwithBrainly

8 0

3 years ago

Read 2 more answers

FIGURE 2 shows a 1.5 kg block is hung by a light string which is wound around a smooth pulley of radius 20 cm. The moment of ine

Sindrei [870]

Answer:

At t = 4.2 s

Angular velocity: 6. 17 rad /s

The number of revolutions: 2.06

Explanation:

First, we consider all the forces acting on the pulley.

There is only one force acting on the pulley, and that is due to the 1.5 kg mass attached to it.

Therefore, the torque on the pulley is

$\tau=Fd=mg\cdot R$

where m is the mass of the block, g is the acceleration due to gravity, and R is the radius of the pulley.

Now we also know that the torque is related to angular acceleration α by

$\tau=I\alpha$

therefore, equating this to the above equation gives

$mg\cdot R=I\alpha$

solving for alpha gives

$\alpha=\frac{mgR}{I}$

Now putting in m = 1.5 kg, g = 9.8 m/s^2, R = 20 cm = 0.20 m, and I = 2 kg m^2 gives

$\alpha=\frac{1.5\cdot9.8\cdot0.20}{2}$ $\boxed{\alpha=1.47s^{-2}}$

Now that we have the value of the angular acceleration in hand, we can use the kinematics equations for the rotational motion to find the angular velocity and the number of revolutions at t = 4.2 s.

The first kinematic equation we use is

$\theta=\theta_0+\omega_0t+\frac{1}{2}\alpha t^2$

since the pulley starts from rest ω0 = 0 and theta = 0; therefore, we have

$\theta=\frac{1}{2}\alpha t^2$

Therefore, ar t = 4.2 s, the above gives

$\theta=\frac{1}{2}(1.47)(4.2)^2$

$\boxed{\theta=12.97}$

So how many revolutions is this?

To find out we just divide by 2 pi:

$\#\text{rev}=\frac{\theta}{2\pi}=\frac{12.97}{2\pi}$ $\boxed{\#\text{rev}=2.06}$

Or about 2 revolutions.

Now to find the angular velocity at t = 4.2 s, we use another rotational kinematics equation:

$\omega^2=w^2_0+2\alpha(\Delta\theta)_{}$

Since the pulley starts from rest, ω0 = 0. The change in angle Δθ we calculated above is 12.97. The value of alpha we already know to be 1.47; therefore, the above becomes:

$\omega^2=0+2(1.47)(12.97)$ $w^2=38.12$ $\boxed{\omega=6.17.}$

Hence, the angular velocity at t = 4.2 w is 6. 17 rad / s

To summerise:

at t = 4.2 s

Angular velocity: 6. 17 rad /s

The number of revolutions: 2.06

3 0

1 year ago

A time-varying horizontal force F(t) = At4 + Bt2 acts for 0.500 s on a 12.25-kg object, starting attime t = 1.00 s. In the SI sy

PSYCHO15rus [73]

Answer:

3.82 Ns

Explanation:

Time varying horizontal Force is given as

F(t) = A t⁴ + B t²

F(t) = 4.50 t⁴ + 8.75 t²

Impulse imparted is given as

$I = \int_{0}^{t}Fdt$

$I = \int_{0}^{1}Fdt$

$I = \int_{0}^{1}(4.50 t^{4} + 8.75 t^{2})dt$

$I = ((0.9) (1)^{5} + (2.92) (1)^{3})$

$I = 3.82 N-s$

7 0

3 years ago

Read 2 more answers

A Chef is looking for a new frying pan that will allow her to cook food quickly at temperatures above 500°C. Use the data provid

makvit [3.9K]

Answer:

Explanation:

1st one

What is your evidence?

Very heavy professional or restaurant pans will have iron handles, while those for home use will be made of brass or stainless steel. All are perfectly safe for oven use.

6 0

2 years ago

How would you describe the sequence of reactions in a hydrogen bomb? A) A fission reaction is used to trigger a fusion reaction.

sertanlavr [38]

The Hydrogen bomb is a thermonuclear bomb where a fission reaction is used to trigger a fusion reaction.

Answer: Option A

<u>Explanation: </u>

The Concept of Hydrogen Bomb or H-Bomb is primarily based on nuclear fusion where different isotopes of hydrogen diffuse to fuse their atomic nuclei into a bigger atom, releasing a significant and enormous amount of energy that can ruin a half of the world.

A hydrogen or thermonuclear bomb contains a firearm, but the reaction process has two stages. Uses primary fission energy to activate the next fusion reaction. The energy out by the fusion is nearly four times more than the energy out during fission, which gives more power to a hydrogen bomb.

8 0

3 years ago