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attashe74 [19]
3 years ago
6

Africa has _____ countries.

Physics
2 answers:
Aliun [14]3 years ago
3 0

According to the United Nations, there are <em>54 </em>countries in Africa today (late 2018).

Nutka1998 [239]3 years ago
3 0

Answer:56

Explanation:count them

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A certain capacitor, in series with a resistor, is being charged. At the end of 10 ms its charge is half the final value. The ti
vichka [17]

To solve this problem we will apply the expression of charge per unit of time in a capacitor with a given resistance. Mathematically said expression is given as

q(t) = e^{-\frac{t}{(R*C)}}

Here,

q = Charge

t = Time

R = Resistance

C = Capacitance

When the charge reach its half value it has passed 10ms, then the equation is,

\frac{1}{2}*q_{final} = e^{-\frac{0.01}{(R*C)}}

Ln(\frac{1}{2}) = -\frac{0.01}{RC}

- RC = \frac{0.01}{Ln(1/2)}

RC = 0.014s

We know that RC is equal to the time constant, then

T = RC  = 0.014s = 14ms

Therefore the time constant for the process is about 14ms

5 0
3 years ago
Mt. Asama, Japan, is an active volcano. In 2009, an eruption threw solid volcanic rocks that landed 1 km horizontally from the c
Nata [24]

Answer:

a) 69.3 m/s

b) 18.84 s

Explanation:

Let the initial velocity = u

The vertical and horizontal components of the velocity is given by uᵧ and uₓ respectively

uᵧ = u sin 40° = 0.6428 u

uₓ = u cos 40° = 0.766 u

We're given that the horizontal distance travelled by the projectile rock (Range) = 1 km = 1000 m

The range of a projectile motion is given as

R = uₓt

where t = total time of flight

1000 = 0.766 ut

ut = 1305.5

The vertical distance travelled by the projectile rocks,

y = uᵧ t - (1/2)gt²

y = - 900 m (900 m below the crater's level)

-900 = 0.6428 ut - 4.9t²

Recall, ut = 1305.5

-900 = 0.6428(1305.5) - 4.9 t²

4.9t² = 839.1754 + 900

4.9t² = 1739.1754

t = 18.84 s

Recall again, ut = 1305.5

u = 1305.5/18.84 = 69.3 m/s

7 0
3 years ago
1-Find the gravitational force
butalik [34]

g = \frac{GMm}{r^2}

where G is the gravitational constant and is about 6.67 * 10^{-11}

g = \frac{6.67 * 10^{-11} * 25 * 0.55}{35^2}

g = \frac{6.67 * 10^{-11} * 25 * 0.55}{1225} = 0.000000000000749 N :D

5 0
3 years ago
An object is traveling with a constant velocity of 5 m/s. How far will it have gone after 7 s?
kozerog [31]
<h3>Answer:</h3>

35 meters

<h3>Explanation:</h3>

<u>Data given;</u>

  • Velocity of an object = 5 m/s
  • Time taken = 7 s

We are required to calculate how far the object traveled.

  • We need to know that;

Velocity = Displacement ÷ time

  • Therefore;

Displacement = Velocity × time

                       = 5 m/s × 7 s

                      = 35 m

Therefore; the object traveled 35 meters

6 0
3 years ago
Almost all cells are microscopic.
Degger [83]

Answer:

It's True...................

4 0
3 years ago
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