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serg [7]
3 years ago
10

a motorist traveling at 18m/s approaches traffic lights when he is 30 m from the stop line they turn red it takes 0.7 s before h

e can react by applying the brakes​
Physics
1 answer:
Gelneren [198K]3 years ago
7 0

Answer:

35.2m

Explanation:

S= V^2 - U^2 ÷ 2A

S= (0) - (18) ÷ 2(4.6)

S= 324 ÷ 92

S= 35.2m

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What is the energy of light that must be absorbed by a hydrogen atom to transition an electron from n = 3 to n = 5?
alina1380 [7]

Answer:

The energy absorbed by a hydrogen atom is 1.549 X10⁻¹⁹ J

Explanation:

Using Bohr's equation; the energy absorbed by the hydrogen atom can be calculated as follows:

\delta E = (\frac{1}{n_2{^2}} -\frac{1}{n_1^{2}})13.6eV

When an electron moves from a lower energy level to a higher energy level, energy is absorbed by the atom.

Lower energy level (n₂) = 3

Higher energy level (n₁) = 5

1 eV = 1.602X10⁻¹⁹ C

\delta E = (\frac{1}{3{^2}} -\frac{1}{5^{2}})13.6X1.602X10^{-19}

ΔE = 1.549 X10⁻¹⁹J

The energy absorbed by a hydrogen atom  to transition an electron from n = 3 to n = 5 is 1.549 X10⁻¹⁹ J

4 0
3 years ago
A positive point charge (q = +5.45 x 10-8 C) is surrounded by an equipotential surface A, which has a radius of rA = 1.49 m. A p
ruslelena [56]

Answer:

r_{B} = 3.34\ m

Solution:

As per the question:

Point charge, q = 5.45\times 10^{- 8}\ C

Test charge, q_{o} = 4.96\times 10^{- 11}\ C

Work done by the electric force, W_{AB} = - 9.05\times 10^{- 9}\ J

Now,

We know that the electric potential at a point is given by:

V = \frac{kqq'}{r}

where

r = separation distance between the charges.

Also,

The work done by the electric force i moving a test charge from point A to B in an electric field:

W_{AB} = kqq_{o}(\frac{1}{r_{B} - \frac{1}{r_{A}}}

- 9.05\times 10^{- 9} = 9\times 10^{9}\times 5.45\times 10^{- 8}\times 4.96\times 10^{- 11}(\frac{1}{r_{B}} - \frac{1}{1.49}}

- 0.3719 = (\frac{1}{r_{B}} - 0.67}

r_{B} = \frac{1}{0.299} = 3.34\ m

5 0
3 years ago
What causes a solar eclipse? Select all that apply.
brilliants [131]

I think it is either D) or E)

But i am going to go with E)

4 0
3 years ago
Read 2 more answers
A 92kg astronaut and a 1200kg satellite are at rest relative to the space shuttle. The astronaut pushes on the satellite, giving
Harman [31]

Answer:

13.7m

Explanation:

Since there's no external force acting on the astronaut or the satellite, the momentum must be conserved before and after the push. Since both are at rest before, momentum is 0.

After the push

m_av_a + m_sv_s = 0

Where m_a = 92kg is the mass of the astronaut, m_s = 1200kg is the mass of the satellite, v_s = 0.14 m/s is the speed of the satellite. We can calculate the speed v_a of the astronaut:

v_a = \frac{-m_sv_s}{m_a} = \frac{-1200*0.14}{92} = -1.83 m/s

So the astronaut has a opposite direction with the satellite motion, which is further away from the shuttle. Since it takes 7.5 s for the astronaut to make contact with the shuttle, the distance would be

d = vt = 1.83 * 7.5 = 13.7 m

4 0
3 years ago
What can be concluded about the atom from knowing that oxygen-18 has an atomic number of 8? A) An oxygen atom that includes 8 ba
anyanavicka [17]
B)

If it is known that the atomic number is 8, we know that the electrons are also 8. Since the atomic mass (O18) is 18, the neutrons are 18-8=10. Option B is the correct answer. 

Hope I helped :) 
4 0
3 years ago
Read 2 more answers
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