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3 years ago

What has to happen for a force to do work on an object?

Physics

1 answer:

dexar [7]3 years ago

4 0

It has to move through a distance over time.

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At noon, ship A is 110 km west of ship B. Ship A is sailing east at 20 km/h and ship B is sailing north at 15 km/h. How fast is

Katyanochek1 [597]

Answer:

$4.47\ \text{km/h}$

Explanation:

$\dfrac{da}{dt}$ = Rate at which the distance between A and starting point of B is changing = -20 km/h

$\dfrac{db}{dt}$ = Rate at which the distance of B is changing = 15 km/h

$\dfrac{dc}{dt}$ = Rate at which the distance between A and B is changing

Time after which the rate at which the distance between A and B is changing is 4 hours

Distance covered by A in 4 hours = $20\times 4=80\ \text{km}$

a = Distance remaining to the start point of B = $110-80=30\ \text{km}$

b = Distance covered by B in 4 hours = $15\times 4=60\ \text{km}$

Distance between A and B after 4 hours

$c=\sqrt{a^2+b^2}\\\Rightarrow c=\sqrt{30^2+60^2}\\\Rightarrow c=67.08\ \text{km}$

$c^2=a^2+b^2$

Differentiating with respect to time we get

$c\dfrac{dc}{dt}=a\dfrac{da}{dt}+b\dfrac{db}{dt}\\\Rightarrow \dfrac{dc}{dt}=\dfrac{a\dfrac{da}{dt}+b\dfrac{db}{dt}}{c}\\\Rightarrow \dfrac{dc}{dt}=\dfrac{30\times -20+60\times 15}{67.08}\\\Rightarrow \dfrac{dc}{dt}=4.47\ \text{km/h}$

The rate at which the distance between the ships is changing at 4 PM is $4.47\ \text{km/h}$ .

7 0

3 years ago

If you're on the orbiting International Space Station with a box of feathers and a box of sand, how could you tell which is whic

const2013 [10]

Answer:

Poke or kick the boxes. The sand box is the one that resists the most

Explanation:

The one that resists the most a change in motion (inertia) is the one with the greater mass—the one filled with sand. Since we cannot open the boxes or perform any weight measurement we can distinguish them by their inertia. Sand has greater mass and thus greater inertia

4 0

3 years ago

Nina is working with electricity and shortens the wires through which the current is flowing. What is Nina most likely trying to

wariber [46]

The answer is D i took the test but got it wrong but i got to see the answers

6 0

3 years ago

Read 2 more answers

What is the meaning of lightyear?

puteri [66]

"Lightyear" is a <em>distance</em> ... specifically, the distance that light travels
through vacuum in one year of 365 days.

It's equivalent to 9.454 x 10^12 kilometers, or 5.875 x 10^12 miles .

7 0

3 years ago

Explain the expression “light travels at a speed”.

Anestetic [448]

Some things travel faster than the speed of light

7 0

3 years ago