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In-s [12.5K]
3 years ago
12

Always been observed to be true, law or theory?

Physics
2 answers:
sattari [20]3 years ago
8 0
A law has always been observed to be true
zavuch27 [327]3 years ago
6 0
Law is something that's observed to be true, such as gravity. We don't know what it really is, but we know it's there.
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A 7450 kg rocket blasts off vertically from the launch pad with a constant upward acceleration of 2.25 m/s2 and feels no appreci
sashaice [31]

Answer:

a) 112.5 m

b) 15.81s

Explanation:

a)We can use the following equation of motion to calculate the velocity v of the rocket at s = 500 m at a constant acceleration of a = 2.25 m/s2

v^2 = 2as

v^2 = 2*2.25*500 = 2250

v = \sqrt{2250} = 47.4 m/s

After the engine failure, the rocket is subjected to a constant deceleration of g = -10 m/s2 until it reaches its maximum height where speed is 0. Again if we use the same equation of motion we can calculate the vertical distance h traveled by the rocket after engine failure

0^2 - v^2 = 2gh

-2250 = 2(-10)h

h = 2250/20 = 112.5 m

So the maximum height that the rocket could reach is 112.5 + 500 = 612.5 m

b) Using ground as base 0 reference, we have the following equation of motion in term of time when the rocket loses its engine:

s + vt + gt^2/2 = 0

500 + 47.4t - 10t^2/2 = 0

5t^2 - 47.4t - 500 = 0

t= \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}

t= \frac{47.4\pm \sqrt{(-47.4)^2 - 4*(5)*(-500)}}{2*(5)}

t= \frac{47.4\pm110.67}{10}

t = 15.81 or t = -6.33

Since t can only be positive we will pick t = 15.81s

7 0
4 years ago
Read 2 more answers
Two blocks with masses M1 and M2 hang one under the other.
Anna35 [415]

Answer:

(a)T= M2 × g,    (b)T= (M1 + M2)g,   (c)T= M2 (a + g) and  (d)T=(M1 + M2) (a + g)

Explanation:

M1 is hanged upper and M2 is lower at Rest.

(a) For M2

T2 = Weight of the Body M2= M2 × g

(b) T1 = Weight of the Body M2 + Weight of the Body M2

T1 = M1 g + M2 g = (M1 + M2)g

M1 is hanged upper and M2 is lower at accelerated upwards ( F = T - W)

(c) For M2

⇒T = M2a + M2g = M2 (a + g)

(d) For M1

T = (M1 + M2) a + (M1 + M2) g

⇒ T = (M1 + M2) (a + g)

5 0
3 years ago
Read 2 more answers
Show explicitly that ▽ . B-0 near a long straight wire carrying a current I. HINT: you may use Cartesian coordinates, but anothe
aivan3 [116]

Answer:

\bigtriangledown.B=0 is proved.

Explanation:

The magnetic field in the long current carrying wire is,

B=\frac{\mu_{0}I }{2\pi r } \phi

Here, I is the current, B is the magnetic field.

Now, by using cylindrical coordinates for the divergence of B.

\bigtriangledown.B=\frac{1}{s} \frac{d}{d\phi} B

Put the value of B in above equation.

\bigtriangledown.B=\frac{1}{s} \frac{d}{d\phi}(\frac{\mu_{0}I }{2\pi r } \phi)\\\bigtriangledown.B=0

Hence, it is prove that for a long current I carrying wire magnetic field divergence that is \bigtriangledown.B=0.

7 0
3 years ago
Light-rail passenger trains that provide transportation within and between cities are capable of modest accelerations. The magni
Mkey [24]
During the first phase of acceleration we have:
v o = 4 m/s;  t = 8 s; v = 13 m/s, a = ?
v = v o + a * t
13 m/s = 4 m / s + a * 8 s
a * 8 s = 9 m/s
a = 9 m/s : 8 s
a = 1.125 m/s²
The final speed:
v = ?;  v o = 13 m/s; a = 1.125 m/s² ;  t = 16 s
v = v o + a * t
v = 13 m/s + 1.125 m/s² * 16 s
v = 13 m/s + 18 m/s = 31 m/s 
3 0
3 years ago
When dissolved in water, an acid or a base breaks down into
Marianna [84]

Answer:

A.) a proton and an electron

4 0
3 years ago
Read 2 more answers
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