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2 years ago

13

You watch distant Sally Homemaker driving nails into a front porch at a regular rate of 1 stroke per second. You hear the sound

of the blows exactly synchronized with the blows you see. And then you hear one more blow after you see the hammering stop. Calculate the distance of Sally from you.

1 answer:

slamgirl [31]2 years ago

3 0

Answer:

343m

Explanation:

From the question Sally hits one blow every second

However, the sound is delayed by that same amount of time (1 sec)

If the speed of sound is 343m/s

Speed = Distance/Time

Speed = 343m/s

Time = 1s

Distance = Speed x Time

= 343 x 1 = 343m

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Lightning occurs when there is a flow of electric charge (principally electrons) between the ground and a thundercloud. The maxi

V125BC [204]

Answer:

$1.25\times 10^{19}\ electrons$

Explanation:

r = Rate of flow of charge = 20000 C/s

t = Time taken = 100 μS

Charge is given by

$Q=rt\\\Rightarrow Q=20000\times 100\times 10^{-6}\\\Rightarrow Q=2\ C$

The charge that flows between the ground and the cloud in this time is 2 C

Number of electrons is given by

$n_e=\dfrac{Q}{e}\\\Rightarrow n_e=\dfrac{2}{1.6\times 10^{-19}}\\\Rightarrow n_e=1.25\times 10^{19}\ electrons$

The number of electrons is $1.25\times 10^{19}\ electrons$

6 0

2 years ago

A car is traveling to the right with a speed of 29m/s when the rider slams on the accelerator to pass another car. The car pas

adoni [48]

Answer:

Acceleration of the car is $1.43\ m/s^2$ .

Explanation:

It is given that,

Initial speed of the car, u = 29 m/s

Finally it reaches a speed of, v = 34 m/s

Distance, d = 110 m

We need to find the acceleration of the car as it speed up. It can be calculated using third law of motion as :

$v^2-u^2=2ad$

$a=\dfrac{v^2-u^2}{2d}$

$a=\dfrac{(34)^2-(29)^2}{2\times 110}$

$a=1.43\ m/s^2$

So, the acceleration of the car as it speeds up is $1.43\ m/s^2$ . Hence, this is the required solution.

6 0

3 years ago

Two 2.0 kg bodies, A and B, collide. The velocities before the collision are ~vA = (15ˆi + 30ˆj) m/s and ~vB = (−10ˆi + 5.0ˆj) m

AleksandrR [38]

Answer:

Part a)

$10\hat i + 15\hat j = \vec v$

Part b)

$\Delta K = 500 J$

Explanation:

As we know that there is no external force on the system of two masses so here total momentum of the system will remains conserved

so we can say

$m_1v_{1i} + m_2v_{2i} = m_1v_{1f} + m_2v_{2f}$

$(2kg)(15\hat i + 30 \hat j) + (2 kg)(-10\hat i + 5\hat j) = 2kg(-5\hat i + 20\hat j) + 2\vec v$

$5\hat i + 35\hat j = (-5\hat i + 20\hat j) +\vec v$

$10\hat i + 15\hat j = \vec v$

Part b)

magnitude of the initial speed of A = $\sqrt{15^2 + 30^2} = 33.54 m/s$

magnitude of the initial speed of B = $\sqrt{10^2 + 5^2} = 11.18 m/s$

magnitude of final speed of A = $\sqrt{5^2 + 20^2} = 20.61 m/s$

magnitude of final speed of B = $\sqrt{10^2 + 15^2} = 18.03 m/s$

Now change in total kinetic energy is given as

$\Delta K = (\frac{1}{2}m_1v_{1i}^2 + \frac{1}{2}m_2v_{2i}^2) - (\frac{1}{2}m_1v_{1f}^2 + \frac{1}{2}m_2v_{2f}^2)$

$\Delta K = (\frac{1}{2}2(33.54)^2 + \frac{1}{2}2(11.18)^2) - (\frac{1}{2}2(20.61)^2 + \frac{1}{2}2(18.03)^2)$

$\Delta K = 500 J$

6 0

3 years ago

Which plate is covering most of two continents ? what two continents?

ololo11 [35]

The plate that is covering most of the two continents is the Eurasian plate.
The continents are <span><span>
1. </span><span> Europe</span></span> <span><span>
2. </span><span> Asia</span></span>
The Eurasian plate is a tectonic plate that amasses the whole continent of what others call as “Eruasia”. It takes part of the oceanic crust that starts from the Mid-Atlantic Ridge and extends itself to northward of the Gakkel Ridge. The size of this plate is for about 67,800,000 km according to statistics and geography.

3 0

2 years ago

Read 2 more answers

When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.

lorasvet [3.4K]

$\large{\underline{\underline{\pmb{\frak {\color {red}{Question:}}}}}}$

$\sf \red{When \: baking \: soda \: is \: mixed \: with \: lemon \: juice, \: bubbles \: are \: formed \: with \: the \: evolution \: of \: a \: gas.}$

$\large{\underline{\underline{\pmb{\frak {\color {blue}{Answer:}}}}}}$

When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. The gas is formed in the reaction is Carbon dioxide. $CO_{2}$ is formed.

The change which happened in this reaction is a chemical change.

$\boxed{ \frak \green{Explanation}}$

Since, in chemical change we can't bring a substance to it's actual form how it was in earlier.

Examples: burning of paper is chemical, since we can't get the fine paper again after it is burnt.

Thus, the above reaction is also a chemical change, since we can't get back the lemon juice how it was earlier.

$\boxed{ \frak \red{Brainlysamurai}}$

5 0

2 years ago