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3 years ago

A student drops a rock from a bridge to the water 12m below. How many seconds does it take the rock to hit the water?

1 answer:

7 0

R = $\frac{g t^{2} }{2}$
r - displacement or height
t - time taken
g = 10 m/s-2
t = square root from 2r/g = $\sqrt{ \frac{2 x 12}{10} }$ = 1.5 seconds

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Kirk wants to know if someone his height will go faster on a bike with a larger frame. What should he do next in order to follow

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Answer:

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3 years ago

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4. Calculate the kinetic energy of a 4.7 kg object moving at a speed of 7 m/s. SHOW YOUR WORK

SashulF [63]

Answer:

$\boxed {\boxed {\sf 115.15 \ J}}$

Explanation:

Kinetic energy is the energy an object possesses due to motion. It is calculated with the following formula.

$E_K= \frac{1}{2} mv^2$

The mass of the object is 4.7 kilograms. The velocity of the object is 7 meters per second.

m= 4.7 kg
v= 7 m/s

Substitute the values into the formula.

$E_K= \frac{1}{2} (4.7 \ kg)(7 \ m/s)^2$

Solve the exponent.

(7 m/s)²= 7 m/s * 7 m/s = 49 m²/s²

$E_K= \frac{1}{2} (4.7 \ kg)(49 \ m^2/s^2)$

Multiply the numbers together.

$E_K = 2.35 \ kg * 49 \ m^2/s^2$

$E_K= 115.15 \ kg*m^2/s^2$

Convert the units. 1 kilogram square meter per square second is equal to 1 Joule.

$E_K= 115.15 \ J$

The object has 115.15 Joules of kinetic energy.

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2 years ago

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A constant net force is applied to an object. Suddenly, the object's mass doubles, but the net force remains the same. For this

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D: Half

We know that,

F = m.a, where F is the force, m is the object's mass and a is the acceleration.

In the first case, we observed that a1 = F/m.

In the second case, we observed that the mass has been doubled, so a2 = F/2m .

By the ratio of the two cases, we get

a1/a2 = F/m / F/2m

or, a1/a2 = 2

or, a1 = 2.a2

or, a1/2 = a2

Therefore, the acceleration gets half of it's original measurement.

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3 years ago

Show that the expression pRT has the same units as the pressure, and thus that the ideal gas law is dimensionally consistent.

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Answer and Explanation:

We have given the expression $\rho RT$

Dimension of $\rho =ML^{-3}$

Dimension of R which is gas constant $=ML^2T^{-2}\Theta ^{-1}M^{-1}$

Dimension of temperature T $\Theta ^{-1}$

And dimension of pressure $ML^{-1}T^{-2}$

Now combine dimension of $\rho RT$ $=ML^{-3}ML^2T^{-2}\Theta ^{-1}M^{-1}\Theta ^{-1}=ML^{-1}T^{-2}$

So the dimension of $\rho RT$ and dimension P is same so there unit will also be same

From ideal gas equation we know that $PV=nRT$

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4 years ago

A student reacted calcium with carbon to form a compound. The calcium atoms transferred electrons to the carbon atoms. The compo

frozen [14]

Answer:

Ionic.

Explanation:

To know the the correct answer to the question given above, let us define the terms covalent and ionic.

Covalent is the term used to characterise a compound which is formed by sharing of electrons between the atoms involved. Thus, the compound formed is called covalent compound.

Ionic is the term used to characterise a compound formed when there is a transfer of electron(s) from the metallic atom to the non-metallic atom. The compound formed is called ionic compound.

Considering the question given above, since the calcium atom transfer electron(s) to the carbon atom, it means the compound is an ionic compound.

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