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3 years ago

When the speed of your car is doubled, by what factor does its kinetic energy increase?

Physics

1 answer:

Tju [1.3M]3 years ago

7 0

Answer:

a. 4

Explanation:

Hi there!

The equation of kinetic energy (KE) is the following:

KE = 1/2 · m · v²

Where:

m = mass of the car.

v = speed of the car.

Let´s see how would be the equation if the velocity is doubled (2 · v)

KE2 = 1/2 · m · (2 · v)²

Distributing the exponent:

KE2 = 1/2 · m · 2² · v²

KE2 = 1/2 · m · 4 · v²

KE2 = 4 (1/2 · m · v²)

KE2 = 4KE

Doubling the velocity increased the kinetic energy by 4.

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What fraction of the volume of an iceberg (density 917 kg/m3) would be visible if the iceberg floats in (a) the ocean (salt wate

kondor19780726 [428]

Answer:

a) 10.4% b) 8.3%

Explanation:

According to Archimedes' principle, any object submerged in a liquid, receives an upward force (called buoyant force) numerically equal to the weight of the volume removed by the liquid.

When this force is equal to the force of gravity on the object (which we call weight, always downward) the object floats in the liquid.

Let's see what happens in the two situations we have:

a) salt water (density 1024 Kg/m³)

We can express the force of gravity on the iceberg, as follows:

Fg = mice*g = ρice*Vice*g

For the Fb (buoyant force) , we have:

Fb= ρsw*Vsub*g, where Vsub, is the fraction of the iceberg volume that is submerged.

So we can replace Vsub as follows:

Vsub = k Vice, where k is the fraction submerged, i.e. 0<k<1.

Therefore, if we need that the iceberg float, we need that Fg=Fb, as follows:

Fg= ρice*Vice*g = Fb =ρsw*k*Vice*g (1)

Simplifying common terms, we have:

ρice/ρsw = k ⇒917 kg/m³ / 1,024 kg/m³ = 0.896

This means that 89.6% of the volume is submerged, i.e. , is not visible, so the visible percentage is just the difference between 100% and 89.6%:

Vvis = 100% - 91,7% = 10.4%

b) For fresh water, we can do the same procedure, repeating (1), with the value for density of fresh water, as follows:

Fg= ρice*Vice*g = Fb =ρsw*k*Vice*g

Simplifying common terms, we have:

ρice/ρsw = k ⇒917 kg/m³ / 1,000 kg/m³ = 0.917

This means that 91.7 % of the volume is submerged, i.e. , is not visible, so the visible percentage is just the difference between 100% and 91.7%:

Vvis = 100% - 91.7 = 8.3%

3 0

4 years ago

Each gas sample has the same temperature and pressure. which sample occupies the greatest volume? each gas sample has the same t

Anit [1.1K]

Answer:

20 gram of H as the greastest volume

Explanation:

Each gas sample has the same temperature and pressure. which sample occupies the greatest volume? each gas sample has the same temperature and pressure. which sample occupies the greatest volume? 40.0 gar 20.0 gne 20.0 gh2 4.0 ghe

Given that,

40.0 g of Ar

20.0 g of Ne

20.0 g of h

24.0 g of he

The ideal gas equation ; Pv = nRT

where P is the pressure, V is the volume, R is the gas constant, T is the temperature, n is the number of mole

which is equal to

n = m / M

where m is the given mass

M is the molar mass

The given gas sample are at the same temperature and pressure,

So, the temperature, pressure and gas constant are fixed.

Therefore the volume is proportional to the given mass and molar mass

V ∝ m/M

Substitute the given mass and molar mass of given masses for comparison

No of mole of Ar = mass / molar mass

= 40 / 40 = 1 mole

No of mole of Ne = mass / molar mass

= 20 / 20 = 1 mole

No of mole of h = mass / molar mass

= 20 / 1 = 20 mole

No of mole of he = mass / molar mass

= 24 / 4 = 6 mole

Hence, 20 gram of H as the greastest volume

3 0

4 years ago

Help please!!!!!!!!!!!!!!!!!!!!

Pavel [41]

Looks like you need to review through the lesson and take notes as it tells you in the lesson what each of these are.

8 0

4 years ago

A coin slides over a frictionless plane and across an xy coordinate system from the origin to a point with xy coordinates (1.40

leva [86]

Answer:

The work done required on the coin during the displacement is 21.75 w.

Explanation:

Given that,

A coin slides over a friction-less plane i.e friction force = 0.

The co-ordinate of the given point is (1.40 m, 7.20 m).

The position vector of the given point is represented by $1.40 \hat i+7.20 \hat j$ .

The displacement of the coin is

$\vec d=1.40 \hat i+7.20 \hat j$

The force has magnitude 4.50 N and its makes an angle 128° with positive x axis.

Then x component of the force = 4.50 cos128°

The y component of the force = 4.50 sin128°

Then the position vector of the force is

$\vec F=(4.50 cos 128^\circ)\hat i+(4.50 sin 128^\circ)\hat j$

$=-2.77 \hat i+3.56 \hat j$

We know that,

work done is a scalar product of force and displacement.

$W=\vec F.\vec d$

$=(-2.77 \hat i+3.56 \hat j).(1.40 \hat i+7.20 \hat j)$

=(-2.77×1.40+ 3.56×7.20) w

=21.75 w

The work done required on the coin during the displacement is 21.75 w.

6 0

3 years ago

An engineer is designing a spring to be placed at the bottom of an elevator shaft. If the elevator cable should happen to break

mamaluj [8]

Answer:

Value that the spring constant k = 12Mg / h

Explanation:

According to 2nd law of Newton:

upward force of the spring= F

The weight of the elevator W = mg

F = Mg = M(5g)

==> F =6Mg.

As the spring is compressed to its maximum distance ie s,the maximum upward acceleration comes just , Hence

F =ks = 6Mg

==> s = 6Mg/k

We have gravitational potential energy turning into elastic potential of the spring as the elevator starts at the top some distance h from the spring, and undergoes a total change in height equal to h + s, so:

Mg(h+s) = 1/2ks2

And plugging in our expression for s:

Mg(h+6Mg/k)= 1/2k(6Mg / k)2

gh + 6M2g2/k = 1/2k(36M2g2 /k2)

Mgh +6M2g2/k = 1/2k(36M2g2 /k2)

gh + 6Mg2/k = 18Mg2 / k

gh = 12Mg2 / k

h = 12Mg / k

k = 12Mg / h

7 0

4 years ago

Read 2 more answers