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2 years ago

5

hai điện tích điểm bằng nhau có độ lớn 6.10^-8C đặt cách nhau một khoảng là r trong dầu hỏa có hằng số điện môi E=2,1. Lực tương

tác tĩnh điện giữa chúng laf3,85.10^-4. tìm r

1 answer:

nadezda [96]2 years ago

5 0

Answer:

hai điện tích điểm bằng nhau có độ lớn 6.10^-8C đặt cách nhau một khoảng là r trong dầu hỏa có hằng số điện môi E=2,1. Lực tương tác tĩnh điện giữa chúng laf3,85.10^-4. tìm r

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A child whose weight is 287 N slides down a 7.20 m playground slide that makes an angle of 31.0Â° with the horizontal. The coeff

natulia [17]

Answer:

a

$H =212.6 \ J$

b

$v = 7.647 \ m/s$

Explanation:

From the question we are told that

The child's weight is $W_c = 287 \ N$

The length of the sliding surface of the playground is $L = 7.20 \ m$

The coefficient of friction is $\mu = 0.120$

The angle is $\theta = 31.0 ^o$

The initial speed is $u = 0.559 \ m/s$

Generally the normal force acting on the child is mathematically represented as

=> $N = mg * cos \theta$

Note $m * g = W_c$

Generally the frictional force between the slide and the child is

$F_f = \mu * mg * cos \theta$

Generally the resultant force acting on the child due to her weight and the frictional force is mathematically represented as

$F =m* g sin(\theta) - F_f$

Here F is the resultant force and it is represented as $F = ma$

=> $ma = m* g sin(31.0) - \mu * mg * cos (31.0)$

=> $a = g sin(31.0)- \mu * g * cos (31.0)$

=> $a = 9.8 * sin(31.0) - 0.120 * 9.8 * cos (31.0)$

=> $a = 4.039 \ m/s^2$

So

$F_f = 0.120 * 287 * cos (31.0)$

=> $F_f = 29.52 \ N$

Generally the heat energy generated by the frictional force which equivalent tot the workdone by the frictional force is mathematically represented as

$H = F_f * L$

=> $H = 29.52 * 7.2$

=> $H =212.6 \ J$

Generally from kinematic equation we have that

$v^2 = u^2 + 2as$

=> $v^2 = 0.559^2 + 2 * 4.039 * 7.2$

=> $v = \sqrt{0.559^2 + 2 * 4.039 * 7.2}$

=> $v = 7.647 \ m/s$

6 0

3 years ago

A race car accelerates from 16.5 m/s to 45.1 m/s in 2.27 seconds. Determine the acceleration of the car.

ioda

Answer:

12.6

Explanation:

4 0

3 years ago

How much power does it take to lift 70.0 N to 5.0 m high in 5.00 s?

lesantik [10]

Answer:

Power = 70 W

Explanation:

Given that,

Force, F = 70 N

Height, h = 5 m

Time, t = 5 s

We need to find the power of the object. We know that,

Power = work done/time

Put all the values,

$P=\dfrac{Fd}{t}\\\\P=\dfrac{70\times 5}{5}\\\\P=70\ W$

So, the required power is 70 W.

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3 years ago

When Karl Kaveman adds chilled grog to his new granite mug, he removes 10.9 kJ of energy from the mug. If it has a mass of 625 g

mrs_skeptik [129]

Answer:

3°C

Explanation:

We can that heat Q=m $c_p$ dT

Where m is the mass $c_p$ = specific heat capacity

dT = Temperature difference

here we have given m=625 g =.625 kg

specific heat of granite =0.79 J/(g-K) = 0.79 KJ/(kg-k)

$T_1$ =25°C

$T_2$ we have to find

we have also given Q=10.9 KJ

10.9=0.625×0.79×(25- $T_2$ )

25- $T_2$ =22

$T_2$ =3°C

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3 years ago

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Why do astronauts float aboard the international space station?

lianna [129]

They’re falling toward earth & moving forward at about the same velocity. because the downward and forward forces are nearly equal, the astronauts are not pulled in any specific direction, so they float . <span>
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3 years ago