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3 years ago

5

True or False: Once the object hits the water, the forces are balanced and the object will stop. Support your answer with reason

ing

1 answer:

PtichkaEL [24]3 years ago

8 0

no because it depends on the wind that day , if the object floats, etc but in other words...... FALSE

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A 65 kg box is lifted by a person pulling a rope a distance of 15 meters straight up at a constant speed. How much Power is requ

Y_Kistochka [10]

Answer:

Power is 1061.67W

Explanation:

Power=force×distance/time

Power=65×9.8×15/9 assuming gravity=9.8m/s²

Power=3185/3=1061.67W

8 0

3 years ago

Why is water always used in energy generation (water -> steam -> turbine) instead of a liquid with a lower specific heat c

frez [133]

There are multiple reasons for this. First of all, water is available in almost every place on the Earth. It doesn't pollute the air, doesn't cause health use and is easily handle.

Other factor is the fact that water has a really high specific heat. This means that water, and more specifically steam, can aborb and transport more energy. A lower heat capacity would imply the need to boil more of the liquid to obtain the same amount of energy. This combine with the fact that water expands at a large rate when boiling, combine with everything mentioned previously, and you get a liquid with all the characteristics that a efficient turbine requires to work.

8 0

3 years ago

A high-jumper, having just cleared the bar, lands on an air mattress and comes to rest. Had she landed directly on the hard grou

Hoochie [10]

Answer:

e. the air mattress exerts the same impulse, but a smaller net avg force, on the high-jumper than hard-ground.

Explanation:

This is according to the Newton's second law and energy conservation that the force exerted by the hard-ground is more than the force exerted by the mattress.

The hard ground stops the moving mass by its sudden reaction in the opposite direction of impact force whereas the mattress takes a longer time to stop the motion of same mass in a longer time leading to lesser average reaction force.

<u>Mathematical expression for the Newton's second law of motion is given as:</u>

$F=\frac{dp}{dt}$ ............................................(1)

where:

dp = change in momentum

dt = time taken to change the momentum

We know, momentum:

$p=m.v$

Now, equation (1) becomes:

$F=\frac{d(m.v)}{dt}$

<em>∵mass is constant at speeds v << c (speed of light)</em>

$\therefore F=m.\frac{dv}{dt}$

and, $\frac{dv}{dt} =a$

where: a = acceleration

$\Rightarrow F=m.a$

also

$F\propto \frac{1}{dt}$

so, more the time, lesser the force.

<em>& </em><u><em>Impulse:</em></u>

$I=F.dt$

$I=m.a.dt$

$I=m.\frac{dv}{dt}.dt$

$I=m.dv=dp$

∵Initial velocity and final velocity(=0), of a certain mass is same irrespective of the stopping method.

So, the impulse in both the cases will be same.

4 0

3 years ago

The relationship between a cathode and an anode involves

astra-53 [7]

It involves electrons.

The cathode is the electrode where electron deficient ions move to.

While the anode is electrode where electron excess ions move to.

So the relationship between Cathode and Anode involves electrons.

C.

5 0

3 years ago

Tim can type 2000 words at a speed of 50 words per minute bobs typing speed is 80 words per minute how much less time did bob ta

Whitepunk [10]

Answer:

15 less mins will be used by Bob

Explanation:

This is because it takes Tim 2000/50= 40mins to type the whole work

While it takes Bob 2000/80= 25 mins

So the difference 40-25= 15mins

Will be 15mins

8 0

3 years ago