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3 years ago

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Order the sequence of ideas that led to Marie Curie’s discovery of radioactive elements. Number the events in chronological orde

r starting with the oldest. Rutherford experimented with particles given off by radioactive elements. Dalton developed the theory that all matter is made of atoms. James Chadwick discovered the neutron.

1 answer:

Marysya12 [62]3 years ago

6 0

Answer:

2 1 3

Explanation:

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A 25.0 kg bag of peat moss sits in the back of a flatbed truck, driving up a hill. The bag experiences a 225N normal force. The

malfutka [58]

Answer:

a

$\theta = 23.32^o$

b

$\mu_s = 0.27$

c

$s = 0.948 \ m$

Explanation:

From the question we are told that

The mass of the bag is $m_b = 25.0 \ kg$

The normal force experienced is $F_n = 225 \ N$

The maximum acceleration of the bag is $a = 2.40 \ m/s^2$

Generally this normal force experience by the bag is mathematically represented as

$F_n = mg cos \theta$

=> $225 = (25 * 9.8) cos \theta$

=> $0.9183 = cos \theta$

=> $\theta = cos^{-1}[0.9183]$

=> $\theta = 23.32^o$

Generally for the bag not to slip , it means that the frictional force is equal to the sliding force

$F_f = F_s$

Hence $F_f$ is mathematically represented as

$F_f = \mu_s * F_n$

While $F_s$ is mathematically represented as

$F_s = m * a$

So

$\mu_s * F_n = m * a$

=> $\mu_s * 225 = 25 * 2.40$

=> $\mu_s = 0.27$

Generally from the workdone equation we have that

$KE_f - KE_i = W_f$

Here $W_f$ is the work done by friction which is mathematically represented as

$W_f = m * g * \mu_k * s$

Here s is the distance covered by the bag

$KE_f$ is zero given that velocity at rest is zero

and

$KE_i = \frac{1}{2} * m* v_i^2$

so

$\frac{1}{2} * m* v_i^2 = m * g * \mu_k * s$

=> $\frac{1}{2} * v_i^2 = g * \mu_k * s$

substituting 2.55 m/s for v_i and 0.350 for \mu_k we have that

$\frac{1}{2} * 2.55^2 = 9.8 * 0.350 * s$

=> $s = 0.948 \ m$

4 0

3 years ago

How did Albert Einstein come up with 3 = mc square pls help

inysia [295]

Answer: He came up with this by using theories like the photoelectric effect, the second offered experimental proof of the existence of atoms, and the third introduced the theory of special relativity.

Explanation: He was explaing the realationship between energy and mass.

Me: Hope this helps!!! May I have brainlist!?

4 0

2 years ago

Which of these pairs of atoms are isotpoes? (Physical Science) Pair A Pair B Pair C # protons 6 8 5 2 12 12 # neutrons 8 8 5 3 1

Aleksandr-060686 [28]

Answer:

I guess that the atoms are:

Protons: 6 8 5 2 12 12

Neutrons: 8 8 5 3 13 14

Now, two atoms are isotopes if they share the same number of protons (so both atoms are the same element) but they have a different number of neutrons.

From the given options, the only two that have the same number of protons but a different number of neutrons are:

Protons 12, neutrons 13

and

Protons 12, neutrons 14.

These two are isiotopes.

4 0

2 years ago

Hans Full is pulling on a rope to drag his backpack to school across the ice. He pulls upwards and rightwards with a force of 22

natka813 [3]

Answer:

2420 J

Explanation:

From the question given above, the following data were obtained:

Force (F) = 22.9 N

Angle (θ) = 35°

Distance (d) = 129 m

Workdone (Wd) =?

The work done can be obtained by using the following formula:

Wd = Fd × Cos θ

Wd = 22.9 × 129 × Cos 35

Wd = 22.9 × 129 × 0.8192

Wd ≈ 2420 J

Thus, the workdone is 2420 J.

3 0

3 years ago

When the cornea and lens of the eye do not properly focus

frutty [35]

Answer:

When there is nearsightedness or myopia

Explanation:

As, in myopia the image is formed in front of the retina.

Which makes things looking at things near very easy, but looking at far away things very difficult.

So concave lens makes things look bigger, so therefore, it is used during myopia, to make things look bigger when they are far away

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3 years ago