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2 years ago

Why do scientists believe that dark matter exists even though it cannot be seen?

Physics

1 answer:

poizon [28]2 years ago

3 0

Because although they cannot see it, they can see it's influence on objects that can be seen, and it's effects.

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In places such as hospital operating rooms or factories for electronic circuit boards, electric sparks must be avoided. A person

FrozenT [24]

Time taken by the rubber-soled shoes to reduce a person's potential from 3.00×10³ V to 100V is 3.91s

The initial potential difference $\Delta V_o$ is related to the final potential difference $\Delta V$ by

$\Delta V=\Delta V_{o} e^{-t / \tau}$

Our target is to find t, so we rearrange equation (1) for t to be

$\Delta V=\Delta V_{o} e^{-t / RC}\\ \ln \left ( \frac{\Delta V}{\Delta V_{o}} \right ) = \frac{-t}{RC}\\ t= -RC \ln \left ( \frac{\Delta V}{\Delta V_{o}} \right ) \tag{2}$

The body has a capacitance 150 pF while the foot has a capacitance 80 pF and both are in parallel connection. So, the equivalent capacitance is

$C= 150 \mathrm{~pF} + 80 \mathrm{~pF} = 230 \mathrm{~pF}$

The shoes of the rubber-soled has resistance $R=5000 \mathrm{~M\Omega}$ . Plug the values for $\Delta V, \Delta V_o$ and C into equation (2) to get the time t.

$t&= -RC \ln \left ( \frac{\Delta V}{\Delta V_{o}} \right ) \\ &= -( 5000 \times 10^{6} \mathrm{~\Omega})(230 \times 10^{-12} \mathrm{~F}) \ln \left ( \frac{100\mathrm{~V}}{3000 \mathrm{~V}} \right ) \\ &= {3.91 \mathrm{~s}}$

Learn more about capacitance here:

brainly.com/question/12644355

#SPJ4

3 0

1 year ago

Car B is rounding the curve with a constant speed of 54 km/h, and car A is approaching car B in the intersection with a constant

levacccp [35]

This question is incomplete, the complete question is;

Car B is rounding the curve with a constant speed of 54 km/h, and car A is approaching car B in the intersection with a constant speed of 72 km/h. The x-y axes are attached to car B. The distance separating the two cars at the instant depicted is 40 m. Determine: the angular velocity of Bxy rotating frame (ω).

Answer:

the angular velocity of Bxy rotating frame (ω) is 0.15 rad/s

Explanation:

Given the data in the question and image below and as illustrated in the second image;

distance S = 40 m

V $_B$ = 54 km/hr

V $_A$ = 72 km/hr

α = 100 m

now, angular velocity of Bxy will be;

ω $_B$ = V $_B$ / α

so, we substitute

ω $_B$ = ( 54 × 1000/3600) / 100

ω $_B$ = 15 / 100

ω $_B$ = 0.15 rad/s

Therefore, the angular velocity of Bxy rotating frame (ω) is 0.15 rad/s

3 0

2 years ago

The pressure at the button of a glass filled with water

-Dominant- [34]

Answer: Plz mark me brainlest.

The pressure in the bottom of the glass is defined as P= (pv)g/A.

V is the Volume.
A is the Area.
G is the acceleration due to gravity.

P is the density.

5 0

2 years ago

9. A 2 liter bottle of Coke weighs about 2 kilograms. If that bottle were combined with an equal amount of anti-Coke, how many J

givi [52]

Answer:

The amount of energy that would be released is equal to 4182 Joules.

Explanation:

Total amount of coke = 2 kg = 2000 g

1 calorie per gram is equal to 4.184 Joules of energy

4.184 J/gC*2000g = 8368 J

1 food calorie is roughly equal to 4186 J

8368 - 4186

Therefore, the amount of energy that would be released is equal to 4182 Joules.

3 0

2 years ago

During which two time intervals does the particle undergo equal displacement?

san4es73 [151]

Answer:

BC and DE

Explanation:

In the given figure, the velocity time graph is shown. We know that the area under v-t curve gives the displacement of the particle.

Area under AB, $d_1=\dfrac{1}{2}\times 2\times 10=10\ m$

Area under BC, $d_2=\dfrac{1}{2}\times 2\times 4=4\ m$

Area under CD, $d_3=\dfrac{1}{2}\times 2\times 7=7\ m$

Area under DE, $d_4=\dfrac{1}{2}\times 2\times 4=4\ m$

Area under EF, $d_5=\dfrac{1}{2}\times 2\times 3=3\ m$

So, form above calculations it is clear that, during BC and DE undergo equal displacement. Hence, the correct option is (c) "BC and DE = 4 meters".

4 0

2 years ago