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3 years ago

May someone please help me?

Physics

1 answer:

Nina [5.8K]3 years ago

7 0

Your answer will be C because that's the only thing that will actually use fossil fuels. everything else in natural and doesn't need fossil fuels.

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A piece of taffy slams into and sticks to another identical piece of taffy that is at rest. The momentum of the two pieces stuck

Yanka [14]

Answer:0.5

Explanation:

Given

Piece of taffy slams in to sticks to another identical piece and stuck into it.

Let m be the mass of taffy and u be the initial velocity of taffy and v be the final velocity of system.

Conserving momentum

$mu=2mv$

$v=\frac{u}{2}$

Initial kinetic energy $=\frac{mu^2}{2}$

Final Kinetic Energy $=\frac{2m(\frac{u}{2})^2}{2}=\frac{mu^2}{4}$

change in kinetic energy $\Delta K.E.=\frac{mu^2}{2}-\frac{mu^2}{4}=\frac{mu^2}{4}$

change in kinetic energy will contribute in heat energy

thus fraction of kinetic energy converted in to heat $=\frac{heat\ energy}{Initial\ kinetic\ Energy} =\frac{\frac{mu^2}{4}}{\frac{mu^2}{2}}=\frac{1}{2}=0.5$

5 0

4 years ago

: A stone is thrown from a rooftop at time t = 0 seconds. Its position at time t is given by r(t)=8t i -5t j +(14.7-4.9t^2)k . T

solniwko [45]

Answer:

A) 14.7 m

B) 1.732s

C) 13.86m east and 8.66 m south

D) 19.42 m/s

Explanation:

Let x,y,z be the short-cut for east, north and up direction i,j,k, respectively

A) at t = 0, the rock is at the roof top. So the height of the roof top is

z(0) = 14.7 - 4.9*0 = 14.7 m

B) When the stone hits the ground z(t) = 0

$14.7 - 4.9t^2 = 0$

$4.9t^2 = 14.7$

$t^2 = 14.7/4.9 = 3$

$t = \sqrt{3} = 1.732 s$

C) the position of the stone when it hits the ground is

$r(t) = 8t \hat{i} - 5t\hat{j} + (14.7-4.9t^2)\hat{k}$

$r(1.732) = 8*1.732 \hat{i} - 5*1.732\hat{j} + 0\hat{k}$

$r(1.732) = 13.86 \hat{i} - 8.66\hat{j} + 0\hat{k}$

So it's 13.86m east and 8.66 m south when it hits the ground

D) First we derive the velocity function by differentiate the position function

$v(t) = r'(t) = 8\hat{i} - 5\hat{j} - 2*4.9t\hat{k}$

The stone hits the ground at t = 1.732 s

$v(1.732) = 8\hat{i} - 5\hat{j} - 2*4.9*1.732\hat{k}$

$v(1.732) = 8\hat{i} - 5\hat{j} - 17\hat{k}$

The magnitude of this is

$v = \sqrt{v_x^2 + v_y^2 +v_z^2} = \sqrt{8^2 + 5^2 +17^2} = \sqrt{377} = 19.42$ m/s

4 0

3 years ago

Which material is used to reduce friction ?

Iteru [2.4K]

Answer:MOST COMMON METHOD IS USING A LUBRICANT -

A lubricant is a substance, usually organic, introduced to reduce friction between surfaces in ... medical examination. It is mainly used to reduce friction and to contribute to a better and efficient functioning of a mechanism. ... For lubricant base oil use, the vegetable derived materials are preferred

OTHER METHODS-

There are a number of ways to reduce friction:

Make the surfaces smoother. ...

Lubrication is another way to make a surface smoother.

Make the object more streamlined.

Reduce the forces acting on the surfaces.

Reduce the contact between the surfaces.

PLEASE DO MARK ME AS THE BRAINLIEST :)

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3 years ago

Is Geothermal Energy renewable? Why or why not? Use in your own words.

Alexxx [7]

Yes, because it's from nature, sometimes nature renews it's sources.

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Helga [31]

I think the answer is (D)

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3 years ago

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